If your engine is off and the fluid is cold, the level can vary widely based on how cold it is (is it ambient at 30° F, 60°F, 90°F, is the trans still slightly warm at 120°F, 150°F?), the amount that's in the torque converter, etc. However, operating temp is fixed and the temp does not vary much when at operating temp, and when the engine is running the torque converter is at proper operating level. This is when the transmission is the most consistent and why this is when the fluid level should be checked.

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k