diff --git a/BresserWeatherSensorLWCfg.h b/BresserWeatherSensorLWCfg.h
index 9d5d1a1..ee8c040 100644
--- a/BresserWeatherSensorLWCfg.h
+++ b/BresserWeatherSensorLWCfg.h
@@ -49,6 +49,7 @@
 // 20240520 Added definitions for AppLayer payload configuration
 // 20240521 Added UBATT_CH/USUPPLY_CH
 // 20240524 Added sensor feature flags
+//          Moved PAYLOAD_SIZE from BresserWeatherSensorLW.ino
 //
 // Note:
 // Depending on board package file date, either
@@ -94,6 +95,10 @@
 //#define ARDUINO_THINGPULSE_EPULSE_FEATHER
 #endif
 
+// Uplink message payload size
+// The maximum allowed for all data rates is 51 bytes.
+const uint8_t PAYLOAD_SIZE = 51;
+
 // Battery voltage thresholds for energy saving & deep-discharge prevention
 
 // If battery voltage <= BATTERY_WEAK [mV], MCU will sleep for SLEEP_INTERVAL_LONG