Wake Up Time Calculator

Work out wake up time instantly with clear inputs, formula shown and shareable results.

About Wake Up Time Calculator

Working forward from bedtime, add the time it takes to fall asleep and then whole sleep cycles. Waking at a cycle boundary avoids the grogginess of being pulled out of deep sleep, and showing the option one cycle earlier gives a fallback when time is short.

Formula

Cycle-based wake time

wake = bedtime + latency + cycles x cycle length

Worked example

With the default values below, Wake Up Time Calculator returns Wake-up time (24h clock) of 6.75. Change any input above and every figure here is recalculated in your browser.

Inputs used

Bedtime hour (24h): 23 h
Sleep cycles: 5 cycles
Time to fall asleep: 15 min
Cycle length: 90 min

Results

Wake-up time (24h clock): 6.75 h
Total sleep: 7.50 h
Wake time one cycle earlier (24h): 5.25 h
Time in bed: 7.75 h

Step by step

1Values used
2Cycle-based wake time
3Wake-up time (24h clock)= 6.75 h
4Total sleep= 7.50 h
5Wake time one cycle earlier (24h)= 5.25 h
6Time in bed= 7.75 h

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why does waking mid-cycle feel awful?

Sleep inertia is worst when you wake from slow-wave sleep. Cycle boundaries fall in light sleep, where waking is easiest.

Is less sleep at a cycle boundary better than more mid-cycle?

Sometimes, for how you feel on waking. Over days, total sleep matters more than cycle alignment.