Compare calculators

Both calculators run independently — change the inputs on either side to compare results.

Sleep Cycle Calculator

Find your ideal bedtime by working backward from your wake-up time in complete 90-minute sleep cycles. Waking at the end of a cycle (rather than mid-cycle) leaves you feeling more refreshed than the same total hours timed less carefully.

Desired Wake Time (hours (24h format))

Number of Sleep Cycles (cycles)

Fill in the required fields to see your result.

Sleep

REM Sleep Calculator

Estimate how much of your nightly sleep is spent in REM based on total sleep time and age. REM sleep is critical for memory consolidation, emotional processing, and creative problem-solving, and is the first stage to be cut short by sleep restriction.

Total Sleep Time (hours)

Age (years)

Fill in the required fields to see your result.

Key differences

	Sleep Cycle Calculator	REM Sleep Calculator
Category	Sleep	Sleep
Inputs required	2	2
Result	Optimal Bedtime (hours)	Estimated REM Sleep (hours)
What it does	Find your ideal bedtime by working backward from your wake-up time in complete 90-minute sleep cycles. Waking at the end of a cycle (rather than mid-cycle) leaves you feeling more refreshed than the same total hours timed less carefully.	Estimate how much of your nightly sleep is spent in REM based on total sleep time and age. REM sleep is critical for memory consolidation, emotional processing, and creative problem-solving, and is the first stage to be cut short by sleep restriction.