---
title: "Sleep Calculator — Best Bedtime & Wake-up Time | WorldCalculators.org"
description: "Find the best time to go to sleep or wake up based on 90-minute sleep cycles. Avoid morning grogginess by waking at the end of a complete sleep cycle."
url: "https://worldcalculators.org/calculators/sleep-calculator/"
canonical: "https://worldcalculators.org/calculators/sleep-calculator/"
---

# Sleep Calculator

Find the best time to go to sleep or wake up based on 90-minute sleep cycles. Avoid morning grogginess by waking at the end of a complete sleep cycle.

## Quick answer

To wake at 7:00 AM feeling rested → go to sleep at 11:16 PM (7.5 hrs) or 9:46 PM (9 hrs). Each sleep cycle = 90 minutes. Add 14 mins to fall asleep. Waking mid-cycle causes grogginess. The magic number is 5 cycles (7.5 hours) for most adults.

## Sleep Recommendations by Country Health Authority

Sources: CDC 2022, NHS UK, WHO Global Status Report on NCDs.

Source: https://worldcalculators.org/calculators/sleep-calculator/
Markdown mirror of the HTML page. Prefer this URL for RAG; the interactive calculator still lives on the HTML page.