is there a way to calculate torque without knowing the power? consider this: P = T * rpm I can calculate rpm easily as I have a tachometer but without power, I can never find the torque. In case of translation, you can find the force propelling an object without knowing the power. For example, if you wanna find the force propelling a car at a constant speed, you find it by calculating drag, which is exactly the force the car is experiencing the opposite way Force propelling the car = drag = 0.5 * rho * V2 * A * CD All quantities in the equation are readily available (or almost) - rho is tabulated - v is easily calculated through speedometer or speed gun - A can be provided - CD can be provided As seen from the equation, no need to know the power. So no need for the equation P = F*V to calculate the force. Now, is there such a way to calculate torque by only knowing rpm and some other variables other than power? I'm asking this because I'm working on a small gas turbine (single shaft - single centrifugal compressor - single turbine) project and I want to calculate the torque acting on the shaft at a constant rpm. I can obtain the rpm through my cheap tachometer but I'm having troubles with calculating the power.