Sleep Debt Calculator
Add up a week of short nights into one honest number, plus a night-by-night plan to pay it back without wrecking your rhythm.
Use the tool →Home › Tools
Free Biohacking Calculators & Tools
Fifteen free tools for sleep, nutrition, fitness and recovery — each built on published formulas, explained honestly, with no sign-up and no miracle claims. Your inputs never leave your device; everything runs in your browser.
Biohacking has a hype problem. These tools are the opposite of hype: a sleep debt calculator that tells you repayment takes weeks, a biological age estimator that admits it is an estimate, an HRV tracker that warns you single-day swings are noise. Every tool shows its maths, cites its sources, and flags where the evidence is thin. That is what "evidence-first" means here — numbers you can act on, and honesty about what they cannot tell you.
Caffeine Half-Life Timer
See how much caffeine is still in your system right now — and the exact time it drops below the sleep-safe threshold.
Use the tool →Optimal Bedtime Finder
Pick a wake time and get three bedtimes aligned to 90-minute sleep cycles, so you wake between cycles, not mid-dream.
Use the tool →Biological Age Estimator
Ten questions, one honest number: how old your habits say your body is — and the three levers that move it most.
Use the tool →VO2 Max Estimator
Estimate your cardio fitness from age and resting heart rate with the Uth–Sørensen–Overgaard formula, rated against norms.
Use the tool →Intermittent Fasting Timer
Track your fast phase-by-phase — fed, post-absorptive, fat-burning ramp, ketosis — with your next phase and eating window.
Use the tool →Protein Intake Calculator
Daily protein targets by goal — sedentary to muscle gain — with per-meal splits and example foods to hit them.
Use the tool →Resting Metabolic Rate Calculator
Your daily calorie burn at rest (Mifflin–St Jeor), plus TDEE for your activity level and cutting/bulking targets.
Use the tool →Body Fat % (US Navy Method)
The Hodgdon–Beckett Navy method with a tape measure — no calipers, no scales, rated against fitness categories.
Use the tool →One-Rep Max Calculator
Turn any set into an estimated 1RM with the Epley formula, plus percentage training tables for programming.
Use the tool →Water Intake Calculator
Daily water target adjusted for weight, activity and climate — with pregnancy and breastfeeding add-ons.
Use the tool →Jet Lag Planner
Shift your sleep one hour a day before you fly, with timed light exposure and honest melatonin guidance.
Use the tool →Nap Optimizer
The right nap length for your goal — 20 minutes or a full 90 — with your wake-up time and a grogginess warning.
Use the tool →HRV Baseline Tracker
Seven mornings of rMSSD, one baseline: is today a train-hard day or a take-it-easy day? With a 7-day chart.
Use the tool →Deep Sleep Estimator
Estimate your deep-sleep minutes from age and habits, compared against the norm — and your top three levers.
Use the tool →No tools match your search. Try "sleep", "protein" or "HRV".
Showing 15 of 15 tools.
How these tools work
Each tool is a single static page: the calculation happens in JavaScript inside your browser, so nothing you type is sent anywhere. The formulas are published ones — Mifflin–St Jeor for metabolic rate, Hodgdon–Beckett for Navy body fat, Uth–Sørensen–Overgaard for VO2 max — and every tool page explains the maths it uses, shows worked examples, and links the key references.
Equally important is what the tools do not do. They do not diagnose, they do not prescribe, and they do not replace your doctor. Estimates like biological age and deep-sleep minutes are models, not measurements; the pages say so plainly. Where the evidence behind a biohacking claim is thin — and in this space it often is — the guide text says that too.
Disclaimer: The information on this page is for general educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or another qualified health provider with any questions you may have regarding a medical condition.