diff --git a/southbridge/src/main.rs b/southbridge/src/main.rs
index 87fc784..abe79a2 100644
--- a/southbridge/src/main.rs
+++ b/southbridge/src/main.rs
@@ -199,7 +199,8 @@ async fn bus_voltage_monitor(adc: ADC, bus: PIN_28) {
 
     loop {
         let level = adc.read(&mut bus_voltage).await.unwrap();
-        SENSOR_DATA.send(SensorData::BusVoltage(level as f32)).await;
+        // empirically calculated against $20 microcenter voltmeter (10k & 33k divider circuit)
+        SENSOR_DATA.send(SensorData::BusVoltage(level as f32 / 251.6763848397)).await;
         Timer::after_millis(3).await;
     }
 }