Rule of Thumb for Reduced / Flex and Max / TOGA Take-Off
N1 reading is the only gauge that verifies the engine is producing expected thrust. "EPR is useless"
N1 for Reduced / Flex is minimum of 85% - normally 86% to 88%
N1 for Max / TOGA is minimum 90% - normally 92% to 97%
Reduced / Flex rated thrust should never be below climb power, if you receive a take-off thrust setting lower than climb, use climb power setting for take-off.