Tools & Calculators
Free, interactive tools that make the invisible visible — your caffeine clearing, your sleep, your body's rhythms — grounded in real data and published science. No ads, no account, and nothing you enter is stored.
All Tools
Daily Caffeine Cutoff Curve
Add your day's drinks and your bedtime — see what's still active at lights-out, and your personal last call.
The Nightcap Curve
Log tonight's drinks — see how far into your sleep the alcohol is still clearing, and what an earlier last call buys back.
The Meal Response Curve
Build a plate, see the typical blood-sugar response — then watch protein, fibre, and a short walk flatten it.
The Sun & Vitamin D Window
Pick your city — see the months the winter sun is too low for your skin to make vitamin D, and what to do about it.
The Iron & Energy Explorer
See your daily iron target and the everyday foods that get you there — then build a day against your number.
The Body Clock Shifter
Jet lag or a new shift — watch your body clock catch up day by day, with light sought and avoided at the right hours.
A calculator you wish existed?
We build new tools when readers ask the same question often enough that we can answer it well — with real data, not a generic formula. Tell us what you’d plug in and what answer you’d want back.