Pricing
$4 a month. The first 100 keep it forever.
The calculator is free and always will be. The app that does the arithmetic for you is $4 a month or $39 a year, with a 30-day refund and no questions.
Monthly
$4
Per month. Cancel any time from your account. No retention flow, no “are you sure.”
Annual
$39
Per year. Two months free against monthly. One decision instead of twelve.
Founding 100
The first 100 subscribers keep $4 a month for as long as they stay subscribed, whatever the price does later. It’s labelled on your account so there’s no argument about it. If you’re reading this before launch, that’s the deal on offer.
What’s free and what isn’t
| Feature | Free | Paid |
|---|---|---|
| Anonymous delta calculator | ✓ | ✓ |
| Science page and every citation | ✓ | ✓ |
| Blog | ✓ | ✓ |
| Account and saved history | — | ✓ |
| Two-number daily logging | — | ✓ |
| 14-day baseline and your delta reveal | — | ✓ |
| Trend line (7-day moving average over raw points) | — | ✓ |
| Mass visualiser | — | ✓ |
| Tomorrow’s target max | — | ✓ |
| Downloads: protocol card, manual tracker, baseline log | — | ✓ |
The refund is the trial
There is no free trial. Trials mean card capture, trial-end emails, and cards that expire. Instead: 30 days, full refund, self-serve button in your account settings, no email required. Your delta reveal lands on day 14, so you reach the payoff while you’re still fully covered.
What you are paying for
A measurement tool. Not a program, not a plan, not coaching. It stores two numbers a day, computes your delta, smooths the noise, sets tomorrow’s ceiling, and shows the mass you’ve moved as a pile of grapefruit on a table. That’s the product. Everything it doesn’t do is on purpose: no food logging, no streaks, no leaderboards, no badges.
Not for everyone
Before you subscribe, the signup asks five questions about whether this is the right tool for you. Under 18 is a hard no. A few other answers ask you to talk to a doctor first. Here’s the full list, so nothing surprises you at checkout.
App launch date and signup link will appear here. Prices in USD. Payments handled by Stripe.