diff --git a/Marlin/Configuration_adv.h b/Marlin/Configuration_adv.h
index 569ff1bf0838..cf54cff991cd 100644
--- a/Marlin/Configuration_adv.h
+++ b/Marlin/Configuration_adv.h
@@ -561,7 +561,7 @@
  * FAST_PWM_FAN_FREQUENCY
  *   Set this to your desired frequency.
  *   For AVR, if left undefined this defaults to F = F_CPU/(2*255*1)
- *            i.e., F = 31.4KHz on 16MHz microcontrollers or F = 39.2KHz on 20MHz microcontrollers.
+ *            i.e., F = 31.4kHz on 16MHz microcontrollers or F = 39.2kHz on 20MHz microcontrollers.
  *   For non AVR, if left undefined this defaults to F = 1Khz.
  *   This F value is only to protect the hardware from an absence of configuration
  *   and not to complete it when users are not aware that the frequency must be specifically set to support the target board.
@@ -571,8 +571,8 @@
  *
  * USE_OCR2A_AS_TOP [undefined by default]
  *   Boards that use TIMER2 for PWM have limitations resulting in only a few possible frequencies on TIMER2:
- *   16MHz MCUs: [62.5KHz, 31.4KHz (default), 7.8KHz, 3.92KHz, 1.95KHz, 977Hz, 488Hz, 244Hz, 60Hz, 122Hz, 30Hz]
- *   20MHz MCUs: [78.1KHz, 39.2KHz (default), 9.77KHz, 4.9KHz, 2.44KHz, 1.22KHz, 610Hz, 305Hz, 153Hz, 76Hz, 38Hz]
+ *   16MHz MCUs: [62.5kHz, 31.4kHz (default), 7.8kHz, 3.92kHz, 1.95kHz, 977Hz, 488Hz, 244Hz, 60Hz, 122Hz, 30Hz]
+ *   20MHz MCUs: [78.1kHz, 39.2kHz (default), 9.77kHz, 4.9kHz, 2.44kHz, 1.22kHz, 610Hz, 305Hz, 153Hz, 76Hz, 38Hz]
  *   A greater range can be achieved by enabling USE_OCR2A_AS_TOP. But note that this option blocks the use of
  *   PWM on pin OC2A. Only use this option if you don't need PWM on 0C2A. (Check your schematic.)
  *   USE_OCR2A_AS_TOP sacrifices duty cycle control resolution to achieve this broader range of frequencies.
@@ -1179,7 +1179,7 @@
 
 /**
  * Adaptive Step Smoothing increases the resolution of multi-axis moves, particularly at step frequencies
- * below 1KHz (for AVR) or 10KHz (for ARM), where aliasing between axes in multi-axis moves causes audible
+ * below 1kHz (for AVR) or 10kHz (for ARM), where aliasing between axes in multi-axis moves causes audible
  * vibration and surface artifacts. The algorithm adapts to provide the best possible step smoothing at the
  * lowest stepping frequencies.
  */
@@ -3419,14 +3419,14 @@
 
   /**
    * PHOTO_PULSES_US may need adjustment depending on board and camera model.
-   * Pin must be running at 48.4KHz.
+   * Pin must be running at 48.4kHz.
    * Be sure to use a PHOTOGRAPH_PIN which can rise and fall quick enough.
    * (e.g., MKS SBase temp sensor pin was too slow, so used P1.23 on J8.)
    *
    *  Example pulse data for Nikon: https://bit.ly/2FKD0Aq
    *                     IR Wiring: https://git.io/JvJf7
    */
-  //#define PHOTO_PULSES_US { 2000, 27850, 400, 1580, 400, 3580, 400 }  // (µs) Durations for each 48.4KHz oscillation
+  //#define PHOTO_PULSES_US { 2000, 27850, 400, 1580, 400, 3580, 400 }  // (µs) Durations for each 48.4kHz oscillation
   #ifdef PHOTO_PULSES_US
     #define PHOTO_PULSE_DELAY_US 13 // (µs) Approximate duration of each HIGH and LOW pulse in the oscillation
   #endif
diff --git a/Marlin/src/HAL/AVR/fastio.cpp b/Marlin/src/HAL/AVR/fastio.cpp
index 8af3ef805efa..5083893ae3fd 100644
--- a/Marlin/src/HAL/AVR/fastio.cpp
+++ b/Marlin/src/HAL/AVR/fastio.cpp
@@ -245,7 +245,7 @@ uint16_t set_pwm_frequency_hz(const_float_t hz, const float dca, const float dcb
   float count = 0;
   if (hz > 0 && (dca || dcb || dcc)) {
     count = float(F_CPU) / hz;            // 1x prescaler, TOP for 16MHz base freq.
-    uint16_t prescaler;                   // Range of 30.5Hz (65535) 64.5KHz (>31)
+    uint16_t prescaler;                   // Range of 30.5Hz (65535) 64.5kHz (>31)
 
          if (count >= 255. * 256.) { prescaler = 1024; SET_CS(5, PRESCALER_1024); }
     else if (count >= 255. * 64.)  { prescaler = 256;  SET_CS(5,  PRESCALER_256); }
@@ -277,7 +277,7 @@ uint16_t set_pwm_frequency_hz(const_float_t hz, const float dca, const float dcb
     // Restore the default for Timer 5
     SET_WGM(5, PWM_PC_8);                 // PWM 8-bit (Phase Correct)
     SET_COMS(5, NORMAL, NORMAL, NORMAL);  // Do nothing
-    SET_CS(5, PRESCALER_64);              // 16MHz / 64 = 250KHz
+    SET_CS(5, PRESCALER_64);              // 16MHz / 64 = 250kHz
     OCR5A = OCR5B = OCR5C = 0;
   }
   return round(count);
diff --git a/Marlin/src/HAL/DUE/HAL_SPI.cpp b/Marlin/src/HAL/DUE/HAL_SPI.cpp
index 2b613a45baec..c5e8f2433d7d 100644
--- a/Marlin/src/HAL/DUE/HAL_SPI.cpp
+++ b/Marlin/src/HAL/DUE/HAL_SPI.cpp
@@ -491,9 +491,9 @@
    *  1 :  4 - 5 MHz
    *  2 :  2 - 2.5 MHz
    *  3 :  1 - 1.25 MHz
-   *  4 :  500 - 625 KHz
-   *  5 :  250 - 312 KHz
-   *  6 :  125 - 156 KHz
+   *  4 :  500 - 625 kHz
+   *  5 :  250 - 312 kHz
+   *  6 :  125 - 156 kHz
    */
   void spiInit(uint8_t spiRate) {
     switch (spiRate) {
diff --git a/Marlin/src/HAL/DUE/fastio/G2_PWM.cpp b/Marlin/src/HAL/DUE/fastio/G2_PWM.cpp
index d9fbabce2148..800915ff692b 100644
--- a/Marlin/src/HAL/DUE/fastio/G2_PWM.cpp
+++ b/Marlin/src/HAL/DUE/fastio/G2_PWM.cpp
@@ -25,7 +25,7 @@
  * is NOT used to directly toggle pins. The ISR writes to the pin assigned to
  * that interrupt.
  *
- * All PWMs use the same repetition rate.  The G2 needs about 10KHz min in order to
+ * All PWMs use the same repetition rate.  The G2 needs about 10kHz min in order to
  * not have obvious ripple on the Vref signals.
  *
  * The data structures are setup to minimize the computation done by the ISR which
diff --git a/Marlin/src/HAL/DUE/pinsDebug.h b/Marlin/src/HAL/DUE/pinsDebug.h
index f01c53c8ce06..6c08585974fd 100644
--- a/Marlin/src/HAL/DUE/pinsDebug.h
+++ b/Marlin/src/HAL/DUE/pinsDebug.h
@@ -53,7 +53,7 @@
  *     The net result is that both the g_pinStatus[pin] array and the PIO_OSR register
  *     needs to be looked at when determining if a pin is an input or an output.
  *
- * b) Due has only pins 6, 7, 8 & 9 enabled for PWMs.  FYI - they run at 1KHz
+ * b) Due has only pins 6, 7, 8 & 9 enabled for PWMs.  FYI - they run at 1kHz
  *
  * c) NUM_DIGITAL_PINS does not include the analog pins
  *
diff --git a/Marlin/src/HAL/DUE/timers.cpp b/Marlin/src/HAL/DUE/timers.cpp
index 6555edece3f3..a7bf7fbd6d85 100644
--- a/Marlin/src/HAL/DUE/timers.cpp
+++ b/Marlin/src/HAL/DUE/timers.cpp
@@ -62,7 +62,7 @@ const tTimerConfig timer_config[NUM_HARDWARE_TIMERS] = {
   Timer_clock1: Prescaler 2 -> 42MHz
   Timer_clock2: Prescaler 8 -> 10.5MHz
   Timer_clock3: Prescaler 32 -> 2.625MHz
-  Timer_clock4: Prescaler 128 -> 656.25KHz
+  Timer_clock4: Prescaler 128 -> 656.25kHz
 */
 
 void HAL_timer_start(const uint8_t timer_num, const uint32_t frequency) {
diff --git a/Marlin/src/HAL/DUE/usb/genclk.h b/Marlin/src/HAL/DUE/usb/genclk.h
index 9831701f836f..cde03bc0d107 100644
--- a/Marlin/src/HAL/DUE/usb/genclk.h
+++ b/Marlin/src/HAL/DUE/usb/genclk.h
@@ -74,9 +74,9 @@ extern "C" {
 //@{
 
 enum genclk_source {
-	GENCLK_PCK_SRC_SLCK_RC       = 0, //!< Internal 32KHz RC oscillator as PCK source clock
-	GENCLK_PCK_SRC_SLCK_XTAL     = 1, //!< External 32KHz crystal oscillator as PCK source clock
-	GENCLK_PCK_SRC_SLCK_BYPASS   = 2, //!< External 32KHz bypass oscillator as PCK source clock
+	GENCLK_PCK_SRC_SLCK_RC       = 0, //!< Internal 32kHz RC oscillator as PCK source clock
+	GENCLK_PCK_SRC_SLCK_XTAL     = 1, //!< External 32kHz crystal oscillator as PCK source clock
+	GENCLK_PCK_SRC_SLCK_BYPASS   = 2, //!< External 32kHz bypass oscillator as PCK source clock
 	GENCLK_PCK_SRC_MAINCK_4M_RC  = 3, //!< Internal 4MHz RC oscillator as PCK source clock
 	GENCLK_PCK_SRC_MAINCK_8M_RC  = 4, //!< Internal 8MHz RC oscillator as PCK source clock
 	GENCLK_PCK_SRC_MAINCK_12M_RC = 5, //!< Internal 12MHz RC oscillator as PCK source clock
diff --git a/Marlin/src/HAL/DUE/usb/osc.h b/Marlin/src/HAL/DUE/usb/osc.h
index 06f59c676a60..953bcbbed1d3 100644
--- a/Marlin/src/HAL/DUE/usb/osc.h
+++ b/Marlin/src/HAL/DUE/usb/osc.h
@@ -93,9 +93,9 @@ extern "C" {
 
 //! \name Oscillator identifiers
 //@{
-#define OSC_SLCK_32K_RC             0    //!< Internal 32KHz RC oscillator.
-#define OSC_SLCK_32K_XTAL           1    //!< External 32KHz crystal oscillator.
-#define OSC_SLCK_32K_BYPASS         2    //!< External 32KHz bypass oscillator.
+#define OSC_SLCK_32K_RC             0    //!< Internal 32kHz RC oscillator.
+#define OSC_SLCK_32K_XTAL           1    //!< External 32kHz crystal oscillator.
+#define OSC_SLCK_32K_BYPASS         2    //!< External 32kHz bypass oscillator.
 #define OSC_MAINCK_4M_RC            3    //!< Internal 4MHz RC oscillator.
 #define OSC_MAINCK_8M_RC            4    //!< Internal 8MHz RC oscillator.
 #define OSC_MAINCK_12M_RC           5    //!< Internal 12MHz RC oscillator.
@@ -105,9 +105,9 @@ extern "C" {
 
 //! \name Oscillator clock speed in hertz
 //@{
-#define OSC_SLCK_32K_RC_HZ          CHIP_FREQ_SLCK_RC               //!< Internal 32KHz RC oscillator.
-#define OSC_SLCK_32K_XTAL_HZ        BOARD_FREQ_SLCK_XTAL            //!< External 32KHz crystal oscillator.
-#define OSC_SLCK_32K_BYPASS_HZ      BOARD_FREQ_SLCK_BYPASS          //!< External 32KHz bypass oscillator.
+#define OSC_SLCK_32K_RC_HZ          CHIP_FREQ_SLCK_RC               //!< Internal 32kHz RC oscillator.
+#define OSC_SLCK_32K_XTAL_HZ        BOARD_FREQ_SLCK_XTAL            //!< External 32kHz crystal oscillator.
+#define OSC_SLCK_32K_BYPASS_HZ      BOARD_FREQ_SLCK_BYPASS          //!< External 32kHz bypass oscillator.
 #define OSC_MAINCK_4M_RC_HZ         CHIP_FREQ_MAINCK_RC_4MHZ        //!< Internal 4MHz RC oscillator.
 #define OSC_MAINCK_8M_RC_HZ         CHIP_FREQ_MAINCK_RC_8MHZ        //!< Internal 8MHz RC oscillator.
 #define OSC_MAINCK_12M_RC_HZ        CHIP_FREQ_MAINCK_RC_12MHZ       //!< Internal 12MHz RC oscillator.
diff --git a/Marlin/src/HAL/DUE/usb/sysclk.h b/Marlin/src/HAL/DUE/usb/sysclk.h
index 4398cc0fc9fa..16db8c86d373 100644
--- a/Marlin/src/HAL/DUE/usb/sysclk.h
+++ b/Marlin/src/HAL/DUE/usb/sysclk.h
@@ -156,9 +156,9 @@ extern "C" {
 
 //! \name Master Clock Sources (MCK)
 //@{
-#define SYSCLK_SRC_SLCK_RC              0       //!< Internal 32KHz RC oscillator as master source clock
-#define SYSCLK_SRC_SLCK_XTAL            1       //!< External 32KHz crystal oscillator as master source clock
-#define SYSCLK_SRC_SLCK_BYPASS          2       //!< External 32KHz bypass oscillator as master source clock
+#define SYSCLK_SRC_SLCK_RC              0       //!< Internal 32kHz RC oscillator as master source clock
+#define SYSCLK_SRC_SLCK_XTAL            1       //!< External 32kHz crystal oscillator as master source clock
+#define SYSCLK_SRC_SLCK_BYPASS          2       //!< External 32kHz bypass oscillator as master source clock
 #define SYSCLK_SRC_MAINCK_4M_RC         3       //!< Internal 4MHz RC oscillator as master source clock
 #define SYSCLK_SRC_MAINCK_8M_RC         4       //!< Internal 8MHz RC oscillator as master source clock
 #define SYSCLK_SRC_MAINCK_12M_RC        5       //!< Internal 12MHz RC oscillator as master source clock
diff --git a/Marlin/src/HAL/DUE/watchdog.cpp b/Marlin/src/HAL/DUE/watchdog.cpp
index 6cbf39d1d11f..e144db8291e3 100644
--- a/Marlin/src/HAL/DUE/watchdog.cpp
+++ b/Marlin/src/HAL/DUE/watchdog.cpp
@@ -39,7 +39,7 @@ void watchdogSetup() {
     uint32_t timeout = TERN(WATCHDOG_DURATION_8S, 8000, 4000);
 
     // Calculate timeout value in WDT counter ticks: This assumes
-    // the slow clock is running at 32.768 KHz watchdog
+    // the slow clock is running at 32.768 kHz watchdog
     // frequency is therefore 32768 / 128 = 256 Hz
     timeout = (timeout << 8) / 1000;
     if (timeout == 0)
diff --git a/Marlin/src/HAL/ESP32/i2s.cpp b/Marlin/src/HAL/ESP32/i2s.cpp
index e9f418689e89..3e77b658360b 100644
--- a/Marlin/src/HAL/ESP32/i2s.cpp
+++ b/Marlin/src/HAL/ESP32/i2s.cpp
@@ -176,7 +176,7 @@ int i2s_init() {
    *
    *   fwclk = fbclk / 32
    *
-   *   for fwclk = 250KHz (4µS pulse time)
+   *   for fwclk = 250kHz (4µS pulse time)
    *      N = 10
    *      M = 20
    */
diff --git a/Marlin/src/HAL/LPC1768/u8g/LCD_pin_routines.c b/Marlin/src/HAL/LPC1768/u8g/LCD_pin_routines.c
index bb203cf8d472..466fc8020335 100644
--- a/Marlin/src/HAL/LPC1768/u8g/LCD_pin_routines.c
+++ b/Marlin/src/HAL/LPC1768/u8g/LCD_pin_routines.c
@@ -26,7 +26,7 @@
  * These are based on the LPC1768 pinMode, digitalRead & digitalWrite routines.
  *
  * Couldn't just call exact copies because the overhead killed the LCD update speed
- * With an intermediate level the softspi was running in the 10-20KHz range which
+ * With an intermediate level the softspi was running in the 10-20kHz range which
  * resulted in using about about 25% of the CPU's time.
  */
 
diff --git a/Marlin/src/HAL/LPC1768/u8g/LCD_pin_routines.h b/Marlin/src/HAL/LPC1768/u8g/LCD_pin_routines.h
index 4661202e8ace..d60d93daddbd 100644
--- a/Marlin/src/HAL/LPC1768/u8g/LCD_pin_routines.h
+++ b/Marlin/src/HAL/LPC1768/u8g/LCD_pin_routines.h
@@ -27,7 +27,7 @@
  * These are based on the LPC1768 pinMode, digitalRead & digitalWrite routines.
  *
  * Couldn't just call exact copies because the overhead killed the LCD update speed
- * With an intermediate level the softspi was running in the 10-20KHz range which
+ * With an intermediate level the softspi was running in the 10-20kHz range which
  * resulted in using about about 25% of the CPU's time.
  */
 
diff --git a/Marlin/src/HAL/NATIVE_SIM/u8g/LCD_pin_routines.cpp b/Marlin/src/HAL/NATIVE_SIM/u8g/LCD_pin_routines.cpp
index 69ea29172482..3b5acc1656cd 100644
--- a/Marlin/src/HAL/NATIVE_SIM/u8g/LCD_pin_routines.cpp
+++ b/Marlin/src/HAL/NATIVE_SIM/u8g/LCD_pin_routines.cpp
@@ -26,7 +26,7 @@
  * These are based on the LPC1768 pinMode, digitalRead & digitalWrite routines.
  *
  * Couldn't just call exact copies because the overhead killed the LCD update speed
- * With an intermediate level the softspi was running in the 10-20KHz range which
+ * With an intermediate level the softspi was running in the 10-20kHz range which
  * resulted in using about about 25% of the CPU's time.
  */
 
diff --git a/Marlin/src/HAL/NATIVE_SIM/u8g/LCD_pin_routines.h b/Marlin/src/HAL/NATIVE_SIM/u8g/LCD_pin_routines.h
index 3c959cd4911e..c27c84e8c398 100644
--- a/Marlin/src/HAL/NATIVE_SIM/u8g/LCD_pin_routines.h
+++ b/Marlin/src/HAL/NATIVE_SIM/u8g/LCD_pin_routines.h
@@ -27,7 +27,7 @@
  * These are based on the LPC1768 pinMode, digitalRead & digitalWrite routines.
  *
  * Couldn't just call exact copies because the overhead killed the LCD update speed
- * With an intermediate level the softspi was running in the 10-20KHz range which
+ * With an intermediate level the softspi was running in the 10-20kHz range which
  * resulted in using about about 25% of the CPU's time.
  */
 
diff --git a/Marlin/src/HAL/SAMD51/timers.cpp b/Marlin/src/HAL/SAMD51/timers.cpp
index ce13dd231ecd..1ad0e360736a 100644
--- a/Marlin/src/HAL/SAMD51/timers.cpp
+++ b/Marlin/src/HAL/SAMD51/timers.cpp
@@ -79,7 +79,7 @@ void HAL_timer_start(const uint8_t timer_num, const uint32_t frequency) {
     rtc->MODE0.INTENCLR.reg = RTC_MODE0_INTENCLR_CMP0;
 
     // RTC clock setup
-    OSC32KCTRL->RTCCTRL.reg = OSC32KCTRL_RTCCTRL_RTCSEL_XOSC32K;  // External 32.768KHz oscillator
+    OSC32KCTRL->RTCCTRL.reg = OSC32KCTRL_RTCCTRL_RTCSEL_XOSC32K;  // External 32.768kHz oscillator
 
     // Stop timer, just in case, to be able to reconfigure it
     rtc->MODE0.CTRLA.bit.ENABLE = false;
diff --git a/Marlin/src/HAL/STM32/sdio.cpp b/Marlin/src/HAL/STM32/sdio.cpp
index 18b4434dfa73..0af5f9040e54 100644
--- a/Marlin/src/HAL/STM32/sdio.cpp
+++ b/Marlin/src/HAL/STM32/sdio.cpp
@@ -59,7 +59,7 @@ DMA_HandleTypeDef hdma_sdio;
 /*
   SDIO_INIT_CLK_DIV is 118
   SDIO clock frequency is 48MHz / (TRANSFER_CLOCK_DIV + 2)
-  SDIO init clock frequency should not exceed 400KHz = 48MHz / (118 + 2)
+  SDIO init clock frequency should not exceed 400kHz = 48MHz / (118 + 2)
 
   Default TRANSFER_CLOCK_DIV is 2 (118 / 40)
   Default SDIO clock frequency is 48MHz / (2 + 2) = 12 MHz
diff --git a/Marlin/src/HAL/STM32/timers.h b/Marlin/src/HAL/STM32/timers.h
index 37512da95986..aad543229e16 100644
--- a/Marlin/src/HAL/STM32/timers.h
+++ b/Marlin/src/HAL/STM32/timers.h
@@ -48,7 +48,7 @@
 #define TIMER_INDEX_(T) TIMER##T##_INDEX  // TIMER#_INDEX enums (timer_index_t) depend on TIM#_BASE defines.
 #define TIMER_INDEX(T) TIMER_INDEX_(T)    // Convert Timer ID to HardwareTimer_Handle index.
 
-#define TEMP_TIMER_FREQUENCY 1000   // Temperature::isr() is expected to be called at around 1KHz
+#define TEMP_TIMER_FREQUENCY 1000   // Temperature::isr() is expected to be called at around 1kHz
 
 // TODO: get rid of manual rate/prescale/ticks/cycles taken for procedures in stepper.cpp
 #define STEPPER_TIMER_RATE 2000000 // 2 Mhz
diff --git a/Marlin/src/HAL/STM32F1/timers.cpp b/Marlin/src/HAL/STM32F1/timers.cpp
index f00ac9e3fb19..112c730b9acc 100644
--- a/Marlin/src/HAL/STM32F1/timers.cpp
+++ b/Marlin/src/HAL/STM32F1/timers.cpp
@@ -40,7 +40,7 @@
  * Timer_clock1: Prescaler   2 ->  36    MHz
  * Timer_clock2: Prescaler   8 ->   9    MHz
  * Timer_clock3: Prescaler  32 ->   2.25 MHz
- * Timer_clock4: Prescaler 128 -> 562.5  KHz
+ * Timer_clock4: Prescaler 128 -> 562.5  kHz
  */
 
 /**
diff --git a/Marlin/src/HAL/TEENSY31_32/timers.h b/Marlin/src/HAL/TEENSY31_32/timers.h
index 85381ea48163..3b073d63ab29 100644
--- a/Marlin/src/HAL/TEENSY31_32/timers.h
+++ b/Marlin/src/HAL/TEENSY31_32/timers.h
@@ -41,7 +41,7 @@ typedef uint32_t hal_timer_t;
 #define FTM0_TIMER_PRESCALE_BITS 0b011
 #define FTM1_TIMER_PRESCALE_BITS 0b010
 
-#define FTM0_TIMER_RATE (F_BUS / (FTM0_TIMER_PRESCALE)) // 60MHz / 8 = 7500KHz
+#define FTM0_TIMER_RATE (F_BUS / (FTM0_TIMER_PRESCALE)) // 60MHz / 8 = 7500kHz
 #define FTM1_TIMER_RATE (F_BUS / (FTM1_TIMER_PRESCALE)) // 60MHz / 4 = 15MHz
 
 #define HAL_TIMER_RATE         (FTM0_TIMER_RATE)
diff --git a/Marlin/src/HAL/TEENSY35_36/timers.h b/Marlin/src/HAL/TEENSY35_36/timers.h
index 63ec5e4895ec..6c342bbe0d25 100644
--- a/Marlin/src/HAL/TEENSY35_36/timers.h
+++ b/Marlin/src/HAL/TEENSY35_36/timers.h
@@ -40,7 +40,7 @@ typedef uint32_t hal_timer_t;
 #define FTM0_TIMER_PRESCALE_BITS 0b011
 #define FTM1_TIMER_PRESCALE_BITS 0b010
 
-#define FTM0_TIMER_RATE (F_BUS / FTM0_TIMER_PRESCALE) // 60MHz / 8 = 7500KHz
+#define FTM0_TIMER_RATE (F_BUS / FTM0_TIMER_PRESCALE) // 60MHz / 8 = 7500kHz
 #define FTM1_TIMER_RATE (F_BUS / FTM1_TIMER_PRESCALE) // 60MHz / 4 = 15MHz
 
 #define HAL_TIMER_RATE         (FTM0_TIMER_RATE)
diff --git a/Marlin/src/HAL/shared/HAL_SPI.h b/Marlin/src/HAL/shared/HAL_SPI.h
index 50a2bf9df21c..6611f9ec4e0f 100644
--- a/Marlin/src/HAL/shared/HAL_SPI.h
+++ b/Marlin/src/HAL/shared/HAL_SPI.h
@@ -38,9 +38,9 @@
  *  1 :  4 - 5 MHz
  *  2 :  2 - 2.5 MHz
  *  3 :  1 - 1.25 MHz
- *  4 :  500 - 625 KHz
- *  5 :  250 - 312 KHz
- *  6 :  125 - 156 KHz
+ *  4 :  500 - 625 kHz
+ *  5 :  250 - 312 kHz
+ *  6 :  125 - 156 kHz
  *
  *  On AVR, actual speed is F_CPU/2^(1 + index).
  *  On other platforms, speed should be in range given above where possible.
diff --git a/Marlin/src/feature/digipot/digipot_mcp4451.cpp b/Marlin/src/feature/digipot/digipot_mcp4451.cpp
index f59e0aae8068..ba5ecdad050a 100644
--- a/Marlin/src/feature/digipot/digipot_mcp4451.cpp
+++ b/Marlin/src/feature/digipot/digipot_mcp4451.cpp
@@ -82,7 +82,7 @@ void DigipotI2C::set_current(const uint8_t channel, const float current) {
 
 void DigipotI2C::init() {
   #if MB(MKS_SBASE)
-    configure_i2c(16); // Set clock_option to 16 ensure I2C is initialized at 400KHz
+    configure_i2c(16); // Set clock_option to 16 ensure I2C is initialized at 400kHz
   #else
     Wire.begin();
   #endif
diff --git a/Marlin/src/gcode/config/M672.cpp b/Marlin/src/gcode/config/M672.cpp
index af74230516e1..257b49471f61 100644
--- a/Marlin/src/gcode/config/M672.cpp
+++ b/Marlin/src/gcode/config/M672.cpp
@@ -53,7 +53,7 @@
 //  b7 b6 b5 b4 ~b4  ... hi bits, NOT last bit
 //  b3 b2 b1 b0 ~b0  ... lo bits, NOT last bit
 //
-void M672_send(uint8_t b) {    // bit rate requirement: 1KHz +/- 30%
+void M672_send(uint8_t b) {    // bit rate requirement: 1kHz +/- 30%
   LOOP_L_N(bits, 14) {
     switch (bits) {
       default: { OUT_WRITE(SMART_EFFECTOR_MOD_PIN, !!(b & 0x80)); b <<= 1; break; } // send bit, shift next into place
diff --git a/Marlin/src/gcode/control/M3-M5.cpp b/Marlin/src/gcode/control/M3-M5.cpp
index ddbbc4ab6835..2cf22e81ce0c 100644
--- a/Marlin/src/gcode/control/M3-M5.cpp
+++ b/Marlin/src/gcode/control/M3-M5.cpp
@@ -43,7 +43,7 @@
  *
  *  If no PWM pin is defined then M3/M4 just turns it on.
  *
- *  At least 12.8KHz (50Hz * 256) is needed for Spindle PWM.
+ *  At least 12.8kHz (50Hz * 256) is needed for Spindle PWM.
  *  Hardware PWM is required on AVR. ISRs are too slow.
  *
  * NOTE: WGM for timers 3, 4, and 5 must be either Mode 1 or Mode 5.
diff --git a/Marlin/src/module/endstops.cpp b/Marlin/src/module/endstops.cpp
index b9c5aebf3915..939dd6d53760 100644
--- a/Marlin/src/module/endstops.cpp
+++ b/Marlin/src/module/endstops.cpp
@@ -352,7 +352,7 @@ void Endstops::init() {
 
 } // Endstops::init
 
-// Called at ~1KHz from Temperature ISR: Poll endstop state if required
+// Called at ~1kHz from Temperature ISR: Poll endstop state if required
 void Endstops::poll() {
 
   TERN_(PINS_DEBUGGING, run_monitor()); // Report changes in endstop status
@@ -403,7 +403,7 @@ void Endstops::not_homing() {
 void Endstops::resync() {
   if (!abort_enabled()) return;     // If endstops/probes are disabled the loop below can hang
 
-  // Wait for Temperature ISR to run at least once (runs at 1KHz)
+  // Wait for Temperature ISR to run at least once (runs at 1kHz)
   TERN(ENDSTOP_INTERRUPTS_FEATURE, update(), safe_delay(2));
   while (TERN0(ENDSTOP_NOISE_THRESHOLD, endstop_poll_count)) safe_delay(1);
 }
diff --git a/Marlin/src/module/planner.cpp b/Marlin/src/module/planner.cpp
index 1f10aba01b8a..17d279cfa5f9 100644
--- a/Marlin/src/module/planner.cpp
+++ b/Marlin/src/module/planner.cpp
@@ -2495,7 +2495,7 @@ bool Planner::_populate_block(block_t * const block, bool split_move,
         if (extruder_advance_K[active_extruder] * block->e_D_ratio * block->acceleration * 2 < SQRT(block->nominal_speed_sqr) * block->e_D_ratio)
           SERIAL_ECHOLNPGM("More than 2 steps per eISR loop executed.");
         if (block->advance_speed < 200)
-          SERIAL_ECHOLNPGM("eISR running at > 10KHz.");
+          SERIAL_ECHOLNPGM("eISR running at > 10kHz.");
       #endif
     }
   #endif
diff --git a/Marlin/src/module/planner.h b/Marlin/src/module/planner.h
index b83c445260f9..380c35755c96 100644
--- a/Marlin/src/module/planner.h
+++ b/Marlin/src/module/planner.h
@@ -883,7 +883,7 @@ class Planner {
     static void finish_and_disable();
 
     // Periodic handler to manage the cleaning buffer counter
-    // Called from the Temperature ISR at ~1KHz
+    // Called from the Temperature ISR at ~1kHz
     static void isr() { if (cleaning_buffer_counter) --cleaning_buffer_counter; }
 
     /**
diff --git a/Marlin/src/module/temperature.cpp b/Marlin/src/module/temperature.cpp
index 0305e5e98ee1..bb1768054ee8 100644
--- a/Marlin/src/module/temperature.cpp
+++ b/Marlin/src/module/temperature.cpp
@@ -3046,8 +3046,8 @@ class SoftPWM {
 };
 
 /**
- * Handle various ~1KHz tasks associated with temperature
- *  - Heater PWM (~1KHz with scaler)
+ * Handle various ~1kHz tasks associated with temperature
+ *  - Heater PWM (~1kHz with scaler)
  *  - LCD Button polling (~500Hz)
  *  - Start / Read one ADC sensor
  *  - Advance Babysteps
@@ -3549,7 +3549,7 @@ void Temperature::isr() {
   adc_sensor_state = next_sensor_state;
 
   //
-  // Additional ~1KHz Tasks
+  // Additional ~1kHz Tasks
   //
 
   #if ENABLED(BABYSTEPPING) && DISABLED(INTEGRATED_BABYSTEPPING)
diff --git a/buildroot/share/PlatformIO/variants/MARLIN_F103VE_LONGER/hal_conf_custom.h b/buildroot/share/PlatformIO/variants/MARLIN_F103VE_LONGER/hal_conf_custom.h
index 3a6b7037adf0..3440343ffa1e 100644
--- a/buildroot/share/PlatformIO/variants/MARLIN_F103VE_LONGER/hal_conf_custom.h
+++ b/buildroot/share/PlatformIO/variants/MARLIN_F103VE_LONGER/hal_conf_custom.h
@@ -118,7 +118,7 @@ extern "C" {
 #endif
 
 #ifndef LSE_STARTUP_TIMEOUT
-  #define LSE_STARTUP_TIMEOUT  50U       // No 32.7KHz LSE on this board, reduced to avoid delays
+  #define LSE_STARTUP_TIMEOUT  50U       // No 32.7kHz LSE on this board, reduced to avoid delays
 #endif
 
 /* Tip: To avoid modifying this file each time you need to use different HSE,