diff --git a/utils/CMakeLists.txt b/utils/CMakeLists.txt
index 813f5c4..438bfc7 100644
--- a/utils/CMakeLists.txt
+++ b/utils/CMakeLists.txt
@@ -20,6 +20,7 @@ target_include_directories(edm4eic_utils
 
 install(FILES
   include/edm4eic/analysis_utils.h
+  include/edm4eic/unit_system.h
   include/edm4eic/vector_utils.h
   include/edm4eic/vector_utils_legacy.h
   DESTINATION include/edm4eic
diff --git a/utils/include/edm4eic/unit_system.h b/utils/include/edm4eic/unit_system.h
new file mode 100644
index 0000000..b06b3a9
--- /dev/null
+++ b/utils/include/edm4eic/unit_system.h
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+// Copyright (C) 2023 Dmitry Kalinkin
+
+#pragma once
+
+namespace edm4eic {
+
+  namespace unit {
+
+    //
+    // This provides definition for a unique unit system for this EDM. It is
+    // neither Geant, nor TGeo. The DD4hep, by default, uses a system matching
+    // the TGeo one.
+    //
+    // +------------+---------------------|-----------------+
+    // | Geant      | TGeo                | EDM4hep/EDM4eic |
+    // +------------+---------------------|-----------------+
+    // | milimeter  | centimeter          | milimeter       |
+    // | nanosecond | second              | nanosecond      |
+    // | MeV        | GeV                 | GeV             |
+    // +------------+---------------------|-----------------+
+    //
+
+    // distance
+    static constexpr double mm = 1.0; // millimeter
+    static constexpr double cm = 1e1 * mm; // centimeter
+    static constexpr double um = 1e-3 * mm; // micrometer
+    static constexpr double nm = 1e-6 * mm; // nanometer
+    static constexpr double m = 1e3 * mm; // meter
+
+    // time
+    static constexpr double ns = 1.0; // nanosecond
+    static constexpr double s = 1e9 * ns; // second
+    static constexpr double ms = 1e6 * ns; // milisecond
+    static constexpr double us = 1e3 * ns; // microsecond
+    static constexpr double ps = 1e-3 * ns; // picosecond
+
+    // energy
+    static constexpr double GeV = 1.0; // giga electron volt
+    static constexpr double MeV = 1e-3 * GeV; // mega electron volt
+    static constexpr double keV = 1e-6 * GeV; // kilo electron volt
+    static constexpr double eV = 1e-9 * GeV; // electron volt
+
+  }
+
+}