Free to use · Open source · No ads
Better odds than the name suggests.
A calm weight-loss app for people doing it on their own. Every morning it tells you the odds you're really losing, and it learns from your own scale and food log, so a rough log is good enough.
An iPhone and Android app, on its way to the App Store and Google Play; start today at slimchance.app. Kilograms, pounds or stone. Bring your weigh-ins from Apple Health or another app.
The scale jumps around. The trend doesn't.
Water, salt and last night's dinner move the scale by a kilo or more from one morning to the next. Slim Chance draws one line through your mornings and reads that instead, so one bad morning never ruins a good week.
Odds, not promises.
Most apps show a number. Slim Chance tells you how much to trust it: every morning, the odds in ten that your weight is really coming off, from the line through your mornings and how much they scatter. Nine in ten means it's working. Five in ten means it's too early to say, and it says so.
On the Progress screen, the rate itself: how fast you're really losing, and the range it could be.
Set a next stop and it tells you what it means, like leaving a BMI band, and calls it reached only when the trend stays there.
When the scale jumps, it tells you why.
The morning the scale goes up for no reason is the morning most people give up. Slim Chance looks at your own log for the reason: a bigger day yesterday, the weekend, a first workout after a break.
It says only what your data shows, and it always ends with what the trend did, which is usually almost nothing.
A rough food log is enough.
Nobody logs every drop of oil. In early results from a test led by the US National Institutes of Health this year, photo-logging apps missed 250 to 345 kcal a meal. Slim Chance doesn't need a perfect log: it compares what you log with what your scale does and sets your budget in your log's own units.
Leave out the same things most days and they cancel out. Slim Chance never asks you to log more.
Search, barcodes, or a photo or a few words with an estimate.
A plan for the moments diets break.
Diets rarely break on a Tuesday lunchtime. They break on Friday night, at the weekend, at ten in the kitchen. Write down now what you'll do then, in your own words, and Slim Chance hands it back to you at that moment.
Plans made this way, ahead of time and this specific, make people clearly more likely to follow through: a medium-to-large effect across 94 studies.
Built for keeping it off.
Losing is the part most apps are built for. Keeping it off is where most people struggle, and most apps stop helping at the goal.
When your trend reaches your goal, Slim Chance changes its job. Your budget becomes what you maintain on, a ceiling sits a little above you, and Today counts the days your trend stayed inside your range: a rate, so a day over costs one day, never the whole count. Go over and your own plan comes back, with one gentle step down.
Already lost the weight, after a diet or a medicine? Start in keep-it-off mode from the first day.
It's the idea from the STOP Regain trial: of people taught to weigh daily and act on a small gain, 46 to 55% regained 2.3 kg or more over 18 months, against 72% of those who weren't.
How it compares
Honestly, including where Slim Chance is behind.
| Slim Chance | MacroFactor | MyFitnessPal | Lose It! | Noom | |
|---|---|---|---|---|---|
| Price | Free to use; optional Plus on its way | About $72 a year | Free with ads; Premium about $80 a year | Free with ads; Premium about $40 a year | About $209 a year |
| Ads | None | None | In the free version | In the free version | None |
| Calorie budget learned from your own scale and log | Yes | Yes | No | No | No |
| Start without an account | Yes | No | No | No | No |
| Open source | Yes, AGPL-3.0 | No | No | No | No |
| iPhone app | Coming to the App Store | Yes | Yes | Yes | Yes |
| Food database | Open Food Facts, plus estimates from a photo or words | Large and curated | Very large, crowd-sourced | Large | Large |
Prices are the US list prices we found in October 2026; they vary by country and offer, so check each app before you buy.
Your data is yours.
Slim Chance keeps your data to run the app for you, and for nothing else.
- No ads, no trackers, and nothing is ever sold.
- Stored in the EU, in Frankfurt.
- Export everything, or delete everything, from Settings.
- Open source: you can read exactly what it does with your data, or run your own copy.
- The privacy page lists every outside service and when it's used.
Questions
Why is it called Slim Chance?
Because most diets give you one. A coin landing on its edge is the textbook slim chance, and it's our mark. Losing weight slowly, with a plan for the hard moments, has much better odds, and the app tells you yours every morning. The name is the joke; the odds are real.
Is Slim Chance free?
The everyday app is free to use: the morning odds, your trend, a calorie budget learned from your own log, food, training, and whether you're getting fitter. Slim Chance Plus, an optional subscription on its way, adds forecasts and milestone predictions, a GLP-1 medication tracker and a postpartum plan. No ads in either, and your data is never sold. The code is open source under the AGPL-3.0.
Do I need an account?
No. Start in one tap. Save it with an email and a password when you want it on another device, or to keep it if you lose your phone.
Does it work on iPhone?
Yes. The iPhone app is on its way to the App Store, with the same two quiet notifications a day as on Android. Until it's there, start at slimchance.app.
Can I use pounds or stone?
Yes. Kilograms, pounds, or stones and pounds, and you can switch at any time.
Can I bring my weigh-ins from another app?
Yes. Import a file from Apple Health, Libra, Happy Scale, MyFitnessPal, Withings, Fitbit, Google Fit, Samsung Health or a spreadsheet, and your trend starts on day one. The file is read on your phone; only one reading a day is saved, and an import can be undone.
What happens when I reach my goal?
Slim Chance asks whether to keep it there or aim a little lower. Keeping it, your budget becomes what you maintain on, a ceiling sits a kilo above your goal, and Today counts the days your trend stays inside that range.
My weight jumps before my period. Can Slim Chance tell?
Yes, if you want it to. Turn on period-aware weight in Settings and mark the first day of each period with one tap. After three cycles Slim Chance knows how much your own mornings move around a period, and says so on those days instead of letting a number scare you. It's off by default and used for nothing else.
I don't log everything I eat. Will it still work?
Yes, as long as you log roughly the same way most days. Slim Chance sets your budget from your log and your scale together, so what you leave out is left out of both.
I don't go to a gym. Is it for me?
Yes. Choose "No gym for now" and a walk a day counts. If you want to keep more muscle while you lose fat, two strength sessions a week help, and you can add them later.
Is it a medical app?
No. Slim Chance helps you keep track and plan; it doesn't diagnose or treat anything. It's for adults. If you're pregnant, have a medical condition or a history of eating disorders, talk to your doctor before you start.
Who makes it?
One developer, building it in the open; every change is public on GitHub.
Guides
Start with today's weight.
Three short questions, then your first number. No email needed.
Start now