diff --git a/doc/Calibration.md b/doc/Calibration.md
index 7682737318..76991b6ce7 100644
--- a/doc/Calibration.md
+++ b/doc/Calibration.md
@@ -27,7 +27,10 @@
 > [!WARNING]
 > For Bambulab X1/X1C users, make sure you do not select the 'Flow calibration' option.
 > 
-> ![uncheck](https://user-images.githubusercontent.com/103989404/221345187-3c317a46-4d85-4221-99b9-adb5c7f48026.jpeg)  
+> ![uncheck](https://user-images.githubusercontent.com/103989404/221345187-3c317a46-4d85-4221-99b9-adb5c7f48026.jpeg)
+
+> [!IMPORTANT]
+> PASS 1 and PASS 2 follow the older flow ratio formula `FlowRatio_old*(100 + modifier)/100`. YOLO (Recommended) and YOLO (perfectist version) use a new system that is very simple `FlowRatio_old±modifier`.
 
 ![flowrate](./images/flow-calibration.gif)