Free · no signup · shows its working
Sleep calculator that shows its working
Enter your wake time and this sleep calculator returns the bedtimes that land you at the end of a sleep cycle — 5 cycles of 90 minutes plus 15 minutes to fall asleep means in bed by 10:45 pm to wake at 6:30 am. Cycle length and time-to-fall-asleep are first-class inputs on the form itself — not tucked behind a settings panel — because 90 minutes is an average, not your personal constant.
90 min is the average — yours may differ.
10–20 min is typical for a healthy sleeper.
Go to bed at one of these times
the arithmetic · 5 cycles × 90 min + 15 m to fall asleep = 7 h 45 m in bed → in bed by 10:45 pm to wake at 6:30 am
An alarm near a cycle boundary may reduce sleep inertia for some people, but cycle length varies from night to night. Treat these as planning estimates. The highlighted option gives most adults enough total sleep; pick a longer one if you're repaying debt.
NextBuild tonight's wind-down routine around this 10:45 pm bedtime — caffeine cutoff, dim lights, and screens off, each step timed backwards. Your selected bedtime carries into the planner.
Planning tool, not medical advice. These figures are population averages for scheduling your sleep — they don't diagnose or treat any condition. See a clinician for persistent sleep problems.
The printable planner
Wind-down routine planner
Your whole evening worked backwards from your bedtime — caffeine cutoff, last meal, dim lights, warm shower, screens off — every step timed, explained, and shaped by your chronotype. Short on time? It scales the routine to what you actually have: 15, 30, 45 or 60 minutes, up to the full two-hour evening. Then print it or save it to this browser.
Build tonight's routine →
The whole sleep-planning toolkit
Core inputs — your age, chronotype, wake and bedtime, cycle length, and sleep latency — carry between the tools that use them, stored only in your browser. Start with the chronotype quiz if you've never thought about your timing.
Sleep Cycle Calculator
Bedtimes from a wake time, alarms from a bedtime — cycle length and latency as dials, not settings.
Bedtime Calculator
Enter your wake time — get the bedtimes that land you at the end of a sleep cycle.
Calculate Wake Up Time
Going to bed at a set time — get the alarms that land you at a cycle boundary.
90 Minute Sleep Cycle Calculator
The 90-minute rule applied properly — with the falling-asleep time most tools skip.
Chronotype Quiz
Lion, bear, wolf or dolphin — 16 questions, transparent scoring, no email gate.
Chronotype Test
The same 16-question test with the scoring ledger shown answer-by-answer.
How Much Sleep Do I Need
Age-banded sleep need from the National Sleep Foundation's published ranges.
Sleep Debt Calculator
Log your last two weeks — see the debt, and a realistic plan to repay it.
Wind-Down Routine Planner
Your pre-bed schedule worked backwards from bedtime — chronotype-shaped, scaled to the time you have. Printable.
Sleep Schedule Calculator
A full week of bedtimes and alarms — including shift-work anchor schedules.
Nap Calculator
Power nap, slow-wave or full cycle — the right nap length and its best window.
REM Sleep Calculator
How much REM a night actually contains, and why your last cycles hold most of it.
Sleep Age Calculator
A playful composite of how your sleep habits compare to your age. Honest about what it is.
Sleep Efficiency Calculator
Time asleep ÷ time in bed — the metric sleep clinics actually track.
Circadian Rhythm Calculator
Light-timing anchors that keep your body clock set: when to seek it, when to dim it.
Jet Lag Calculator
Direction-aware recovery: how long adjustment takes, and how to pre-shift before you fly.
Methodology & sources
Every figure on this site, cited. The model, the maths, the references.
Why most sleep calculators get it wrong
They freeze two numbers that are only averages: a 90-minute cycle and the time it takes to fall asleep. The strongest incumbents do let you change both — calculator.net has offered cycle length and latency for years — but tucked behind a settings disclosure, and a setting nobody opens behaves like a constant. Real cycle length runs 70–120 minutes between people, and a healthy sleeper takes 10–20 minutes to drop off. Every tool here puts both dials on the form itself, shows the arithmetic with your own numbers substituted in, and keeps the result above the fold with no signup wall between you and the answer.
Sleep calculator FAQ
How does this sleep calculator work?
It counts sleep in cycles of about 90 minutes — the average length of one trip through light sleep, deep sleep and REM. You give it a wake time; it subtracts whole cycles plus the time you take to fall asleep (default 15 minutes) and returns the bedtimes that land you waking at the end of a cycle rather than in the middle of deep sleep. Both the cycle length and the latency are adjustable, because 90 minutes is a population average, not a rule.
What time should I go to bed to wake up at 6:30 am?
With an average 90-minute cycle and 15 minutes to fall asleep: 10:45 pm for 5 cycles (7 h 30 m of sleep), 9:15 pm for 6 cycles (9 h), or 12:15 am for 4 cycles (6 h). Most adults should take the 5-cycle option. Enter your own wake time above to get exact figures for your cycle length.
Is the 90-minute sleep cycle real?
It is a real average, not a constant. Published cycle lengths range roughly 70–120 minutes between people, and your own cycles lengthen across the night — early cycles are deep-sleep heavy, late cycles REM-heavy. That is why every calculator on this site lets you change the cycle length instead of hardcoding 90.
Is this free? Do I need an account?
Everything on this site is free with no account, no email and no signup. Your inputs are stored only in your own browser (localStorage) so settings persist between visits; nothing is uploaded.
Is this medical advice?
No. These are planning tools built on population averages for scheduling sleep. They do not diagnose or treat insomnia, sleep apnoea or any other condition. If poor sleep persists for more than a few weeks, see a clinician.
How we source this
The sleep-duration figures come from the National Sleep Foundation's 2015 consensus panel (Hirshkowitz et al., Sleep Health) — 18 experts convened from 12 stakeholder organisations, reviewing 300+ studies. The cycle, REM, jet-lag and wind-down models are built from the primary literature, and every source is listed with its context on the methodology & sources page.
Content is written and maintained by the SleepMaxx Calculator editorial team and checked against those sources. This site is not medically reviewed — no clinician reviews this content, and we would rather say that in plain text than hang a reviewer byline we don't have. These are planning tools built on population averages; for a personal sleep problem, a clinician is the right next step.
You will also not find an Epworth Sleepiness Scale, a STOP-BANG questionnaire or an AHI estimator here. Those are clinical screening instruments: their scores only mean something in the hands of someone who can act on them, and hosting them on a calculator site is a safety problem, not a feature. We exclude them deliberately.