We illustrate that if the velocity triangles for a compressor, run to two different conditions and have the same angles and Mach numbers, then the non-dimensional parameters (speed, pressure ratio, temperature ratio, etc.) will also be the same. Without resorting to higher mathematics, this method is extended to cover whole engine parameters such as fuel flow, thrust and power. We show how to correct the non-dimensional parameters to standard conditions using exponents for δ (P/PISA) and Θ (T/TISA) and the use of the cycle model to derive the exponent values for each parameter including humidity and “real engine” effects.