diff --git a/src/airtime.cpp b/src/airtime.cpp
index bc827f27..df32ca1b 100644
--- a/src/airtime.cpp
+++ b/src/airtime.cpp
@@ -114,7 +114,7 @@ float AirTime::utilizationTXPercent()
         sum += this->utilizationTX[i];
     }
 
-    return (float(sum) / float(MINUTES_IN_HOUR * 10 * 1000)) * 100;
+    return (float(sum) / float(MS_IN_HOUR)) * 100;
 }
 
 AirTime::AirTime() : concurrency::OSThread("AirTime") {}
diff --git a/src/airtime.h b/src/airtime.h
index a0738140..ecaa1203 100644
--- a/src/airtime.h
+++ b/src/airtime.h
@@ -28,6 +28,9 @@
 #define SECONDS_PER_PERIOD 3600
 #define PERIODS_TO_LOG 24
 #define MINUTES_IN_HOUR 60
+#define SECONDS_IN_MINUTE 60
+#define MS_IN_HOUR (MINUTES_IN_HOUR * SECONDS_IN_MINUTE * 1000)
+
 
 enum reportTypes { TX_LOG, RX_LOG, RX_ALL_LOG };