Free Circadian Rhythm Calculator

Estimate your optimal sleep, wake, and peak performance times based on your chronotype.

Save
hour

Optimal Wake Time

7.0 hour

Peak Alertness9.5 hour
Afternoon Energy Dip14.0 hour
Optimal Bedtime23.0 hour
Melatonin Onset21.0 hour

Optimal Wake Time vs Natural Wake Time (24h)

View formula & how it works →

Circadian Rhythm Timing

Your circadian rhythm is an internal 24-hour clock that regulates sleep, alertness, and hormone release.

Key Time Points (Relative to Wake)

EventHours After Wake Peak alertness+2.5 hours Best coordination+5 hours Afternoon dip+7 hours Melatonin onset+14 hours Optimal bedtime+16 hours

Chronotypes

  • Early birds naturally wake 1-2 hours earlier
  • Night owls naturally wake 1-2 hours later
  • Most people are intermediate

    • Example Calculation

    An intermediate chronotype who naturally wakes at 7 AM.

    1. 01Optimal wake = 7:00 AM
    2. 02Peak alertness = 9:30 AM
    3. 03Afternoon dip = 2:00 PM
    4. 04Melatonin onset = 9:00 PM
    5. 05Optimal bedtime = 11:00 PM

    Frequently Asked Questions

    Learn More

    Understanding BMI: What It Means and How to Calculate It

    Learn what BMI is, how to calculate it, what the ranges mean, and the limitations of body mass index as a health metric. Comprehensive guide with formulas and context.

    Related Calculators

    Sleep Cycle Planner

    Plan sleep cycles.

    Sleep Debt

    Calculate sleep debt.

    Screen Time Impact

    Assess screen time effects.