An independent plateau calculator, built to be honest about the stall.
whenwilliplateau.com forecasts the date and weight your weight loss will stall at a fixed calorie intake — and the lower intake you'd need to keep losing. It's free, runs entirely in your browser, and models the one thing most calculators skip: your metabolism falling as you lose.
Who runs this
whenwilliplateau.com is published by Red Goggles LLC, an independent operator of free web calculators and reference tools. We are not a doctor, dietitian, clinic, supplement seller, diet program, or medical organization, and we are not affiliated with the NIH, NIDDK, or any nutrition or fitness body. We don't sell anything, we don't collect leads, and we don't take your information — the calculator runs on your device, and nothing you type is sent to us.
Why this site exists
Most weight-loss calculators assume your metabolism never changes. Punch in a deficit and they promise the same loss, week after week, all the way to your goal. That's why people lose steadily for a while, then watch the scale freeze at the same calories that were working a month ago — and assume they did something wrong. They didn't. A smaller body burns fewer calories, and your metabolism adapts on top of that, so a working deficit quietly closes and loss flattens into a plateau. This tool exists to give that stall a concrete shape: a date, a weight, and what to do next — instead of "just eat less."
How it's calculated
The forecast is built in the open from published, long-established fitness science:
- Resting metabolism — Mifflin-St Jeor equation.
10·kg + 6.25·cm − 5·age + (5 male / −161 female), validated against indirect calorimetry in 498 adults (Mifflin & St Jeor, Am. J. Clin. Nutr. 1990). Daily burn is RMR multiplied by a conventional activity factor (1.2 sedentary → 1.9 extra-active). - A falling, dynamic loss curve. As you lose mass, RMR and total burn drop, so the deficit shrinks with every pound. We model the loss curve as that closing gap — not the flat "3,500 calories × weeks" line static calculators use.
- Metabolic adaptation (adaptive thermogenesis). Beyond the smaller-body effect, the body burns a bit less than its new size alone predicts. Measured adaptation runs roughly 100–500 cal/day after meaningful loss (Hall and colleagues, NIH); we fold in a conservative share. This is a disclosed estimate, not a measured personal constant.
- A safe-intake floor. The resume-loss target never drops below conservative general guardrails (~1,200 cal/day women, ~1,500 cal/day men). These are rules of thumb, not a medical threshold for any individual, and are enforced on every output.
The full method and its assumptions are laid out on the calculator page under How it works and the "Model & assumptions" panel beside the result.
How we stay honest and current
We're explicit that this is a directional estimate, not a measurement. The exact date and weight vary per person, and we say so at the point of output. We don't model GLP-1 medications, thyroid conditions, PCOS, or other medical factors, and we don't do eating-disorder-adjacent framing — no "eat as little as you can," no glorified extreme deficits. The plateau is presented as normal physiology, not personal failure. The model carries a dated "last reviewed" note and links to its primary sources so you can check the figures yourself.
How the site is funded
whenwilliplateau.com is free and supported by display advertising. Ads are kept calm and never mix with your inputs — we never share your weight, intake, or any other value you enter with advertising or analytics partners. See our privacy page for exactly what is and isn't collected.
Questions or corrections? Reach us on the contact page.