The following chart is supposed to give you an idea of changes of your RPM while using a different propeller on your model.
Calculated RPM you get after filling in your real RPM is only approximate. It is based on our measurements of electic motors. You must always consider actual condition of your engine and exhaust system and also if your engine is running in optimal RPM.
Please always fill in RPM for one size of propeller only and into the green field.