diff --git a/Core/Src/PSE_unit.c b/Core/Src/PSE_unit.c
index d75affa..20006eb 100644
--- a/Core/Src/PSE_unit.c
+++ b/Core/Src/PSE_unit.c
@@ -5,6 +5,7 @@
  *      Author: leo
  */
 
+#include "pse_stepper_planer.h"
 #define _GNU_SOURCE
 
 #include "PSE_unit.h"
@@ -127,5 +128,7 @@ void pse_unit_compute_volume_delivered(pse_unit* unit){
 }
 
 void pse_unit_compute_volume_per_step(pse_unit* unit){
-	unit->nL_per_step = 10;
+	uint64_t numerator = (uint64_t)1 * (unit->syringe->diameter * unit->syringe->diameter) * PSE_STEPPER_SCREW_PITCH;
+	uint64_t denominator = (uint64_t)1273238 * PSE_STEPPER_STEPS_PER_ROTATION;
+	unit->nL_per_step = numerator / denominator;
 }