Free Health Calculators: Sleep, Caffeine & Nutrition Tools

Eleven free, research-based calculators for sleep, caffeine, nutrition and supplements. Every tool shows its math, explains the science in plain language and links the original studies.

Caffeine cutoff calculatorWhen to have your last coffee for your bedtime.Open tool →Sleep, focus & stress quizSix questions to find your H&C stack, with a shareable result card.Open tool →Sleep cycle calculatorBedtimes and wake-up times that line up with full 90-minute cycles.Open tool →Caffeine counterAdd up today's drinks against the FDA's 400 mg reference.Open tool →Magnesium intake checkerTap in today's foods and see how close you are to your RDA.Open tool →Creatine dose calculatorISSN-described loading and daily amounts for your weight.Open tool →Protein needs calculatorYour daily protein range for your weight and activity.Open tool →Water intake calculatorDaily water from drinks and food, in fl oz or liters.Open tool →Vitamin D sun-time estimatorRough midday sun time for your skin type and the UV index.Open tool →BMR & TDEE calculatorResting and daily calorie estimates with Mifflin-St Jeor.Open tool →BMI calculatorBody mass index with NIH adult categories.Open tool →

About these tools

Health & Cognition tools are built to teach as well as calculate. Each one runs in your browser with nothing to sign up for, and your answers stay on your device.

Start with sleep and caffeine if energy is your focus: the caffeine cutoff calculator, caffeine counter and sleep cycle calculator work together. For nutrition, the protein, water and magnesium tools turn guidelines from the National Academies, the NIH and the International Society of Sports Nutrition into simple daily targets. The supplement quiz pulls it together into a starting stack.

How it works

Every tool shows its math, explains the science in plain language, and links the original research, so you learn how it works as well as getting a number.

No sign-up, no tracking of your answers: everything runs in your browser.

Glossary

Peer-reviewed
Checked by independent experts before publication.
Meta-analysis
A study that pools results from many studies.
RDA
Recommended Dietary Allowance.

Frequently asked questions

Are these health calculators free?

Yes. Every tool is free with no sign-up, and calculations run in your browser.

Where do the numbers come from?

Each tool cites its sources, including NIH fact sheets, the National Academies, the FDA, USDA FoodData Central and peer-reviewed studies.

Are these tools medical advice?

No. They're for information only and general wellness education.

Do the tools use US units?

Yes. Pounds, feet and inches, and fluid ounces come first, with a metric toggle on every tool that needs one.

Sources
  1. Each tool lists its own sources on its page.

For information only, not medical advice.