Free Resources
Circadian Tools.
Calculators and assessments to help you understand your biology before you even download the app.
Caffeine Half-Life Calculator
Find out exactly when you need to stop drinking coffee to protect your deep sleep. Calculates active milligrams based on standard metabolic decay.
Huberman Sleep Cocktail Builder
Optimize dosage, safety, and timings of Stanford's recommended sleep compounds based on your specific nighttime struggles.
Circadian Jetlag Planner
Shift your circadian rhythm. Generate a personalized 3-day phase advance/delay schedule based on origin and destination offsets.
Chronotype Compatibility Quiz
Map sleep schedule compatibility with your partner. Discover alert/sleep overlap graphs and cohabitation adjustments.
Chronotype Quiz
Are you a Lion, Bear, Wolf, or Dolphin? Take this quick 2-minute assessment to discover your biological sleep preference.
Social Jetlag Calculator
Calculate how many time zones you are biologically flying every weekend by sleeping in, and see the impact on your Monday morning.
Sleep Debt Calculator
Calculate your cumulative sleep debt over the last 5 days and get advice on how to recover safely without ruining your rhythm.
Sunlight Window Calculator
Calculate exactly how many minutes you need to stand outside based on today's weather to reset your master clock.
Chronotype Visualizer
Slide through the day to see how your master hormones (cortisol and melatonin) fluctuate based on your chronotype.
Sleep Cycle Calculator
Calculate the exact times to go to bed or wake up based on 90-minute sleep cycles. Banish morning grogginess and sleep in sync with your brain.
Why We Built Free Circadian Tools
Most health apps track your past. They tell you how poorly you slept last night or how many steps you took yesterday. But by the time you see that data, it's too late to change it. Circadian biology is about predicting and shaping your future. It's about knowing what to do *right now* to guarantee a better tomorrow.
We built these free calculators and quizzes because understanding your biological rhythm shouldn't require a wearable or a subscription. Knowing your genetic chronotype (whether you are a Lion, Bear, Wolf, or Dolphin) and understanding the caffeine half-life in your bloodstream are foundational concepts of human performance.
Use these tools to get a baseline understanding of your body's internal clock. When you are ready to automate these calculations and receive a personalized daily protocol, download the ARC app.