Live on the Lock Screen
A Live Activity keeps the countdown where you already look, Dynamic Island included. iOS retires it after about eight hours; opening the app starts it over.
iPhone · Apple Watch · Lock Screen
Weight loss,
as a countdown.
A scale tells you where you were this morning. Caldown tells you where you are right now — one number, falling every second, fed by Apple Health.
One-time $10. No subscription, no account, no server.
Countdown10 kg goal
kcal left41,286.7346.4% done
Synced just now · from Apple Health
Approx. end date—~56 days left · 740 kcal/day deficit
The whole idea
One constant does all the work.
- 1 kg of body fat
- ≈ 7,700 kcal
- your goal
- × 10 kg
- to burn
- 77,000 kcal
That is weight loss, written out as arithmetic. Every other number in the app is that one, minus what you have burned, plus what you have eaten.
How it works
Three things to do.
Two of them once.
- 01
Set a goal in kilos.
Caldown multiplies it by 7,700 and that is your number. Resting burn comes from Mifflin–St Jeor — weight, height, age, sex — and Health fills those in for you if you would rather not type them.
- 02
Burn it down.
Active and resting energy arrive from Apple Health in the background. Between syncs the number keeps falling at your resting rate, every second, so it never sits there looking broken.
- 03
Eat, and it goes back on the clock.
Log a meal and those calories return to the total — and get written to Health as a sample you own. Delete the entry in Caldown and it disappears from Health too.
Everywhere you look
The number follows you around.
On your wrist
A native watchOS app with its own widget, kept in step with the phone.
Home Screen widget
The same number, without opening anything.
Apple Health, both directions
Reads active and resting energy, plus weight, height, age and sex. Writes every food entry back as a Health sample — your data stays yours, in the place you already keep it.
A date, not just a number
The projection runs on your real average daily deficit and names the day you land.
No Apple Watch? Still fine
With no resting-energy data to read, Caldown falls back to your BMR and keeps ticking.
Private by construction
Nothing leaves the phone.
There is no account to create and no server to sign in to, because there is no server. Health data is read on-device, and the only thing Caldown hands it to is its own widgets, through a private App Group. No analytics, no tracking, no network calls at all.
And the caveat, said plainly: 7,700 kcal per kilogram is an average, weight loss is never quite linear, and every resting-burn figure — Apple's or ours — is an estimate. Treat the end date as a projection, not a promise.
Pick a number.
Burn it down.
$10
one time · yours for good
- Every feature, Watch app and widgets included
- No subscription, no tiers, no in-app purchases
- No ads, no account, no tracking
Caldown is in testing on real wrists. This page gets the link the day it ships.