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Sleep Cycle Calculator — Wake Up Refreshed

Calculate when to sleep or when to wake up to align with 90-minute sleep cycles. Wake at the end of a cycle to avoid grogginess.

Sleep at one of these times to wake feeling rested:

2:16 AM

3 cycles

4.5 hours sleep

12:46 AM

4 cycles

6 hours sleep

Recommended

11:16 PM

5 cycles

7.5 hours sleep

Recommended

9:46 PM

6 cycles

9 hours sleep

Each sleep cycle is ~90 minutes. Waking at the end of a cycle (light sleep) feels more refreshing.

Calculations assume 14 minutes to fall asleep — the average for adults.

About this tool

Why timing matters

Sleep happens in roughly 90-minute cycles of light → deep → REM sleep. Waking up in the middle of deep sleep makes you feel groggy for hours. Waking at the end of a cycle (light sleep) feels refreshing — even if you slept less total. This tool plans your bedtime or alarm to land on a cycle boundary.

How to use the Sleep Cycle Calculator

Takes about a minute. No signup, no download, your data stays in your browser.

  1. 1
    Open the tool. Scroll up to the Sleep Cycle Calculator above — it loads instantly in your browser, no install needed.
  2. 2
    Enter your values. The fields come pre-filled with realistic defaults so you can see how it works — replace them with your own numbers.
  3. 3
    Read the result. The output updates instantly. Copy or share it — nothing is uploaded to a server, everything stays on your device.

Frequently asked questions

Common questions about the Sleep Cycle Calculator.

Is the Sleep Cycle Calculator free to use?

Yes. The Sleep Cycle Calculatoron 7BusyBoss is completely free — no signup, no paywall, no usage cap. We do recommend paid alternatives in a sidebar card, but the core tool stays free.

Do I need to sign up to use the Sleep Cycle Calculator?

No. The Sleep Cycle Calculatorworks instantly in your browser — no account needed. Signing in with Google is optional and only unlocks features like saving favorites and higher AI build limits.

Does the Sleep Cycle Calculator work on mobile?

Yes. Every tool on 7BusyBoss is mobile-responsive and works in any modern browser — Chrome, Safari, Firefox, Edge — on phones, tablets and desktops.

Is my data safe when I use the Sleep Cycle Calculator?

Yes. The Sleep Cycle Calculatorruns entirely in your browser — your inputs never leave your device unless the tool explicitly fetches public data (e.g. currency rates). We don't store the values you type.

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