Free tool
Weight loss goal calculator
Pick a weekly rate you could actually hold. The week count is a straight line. Your body is not. Use it as a ceiling on optimism, not a promise.
Updated 2026-08-16By Chris RichardsAll tools
Your estimate
weeks at 0.4 kg / week · ~440 kcal / day gap (3,500 kcal/lb rule — real timelines are slower)
Estimate only — verify with a weight log over 2–3 weeks. Not medical advice.
How the estimate is built
Subtract goal from current weight. Divide by the weekly loss you chose. That is weeks on a straight line. The daily calorie gap shown beside it uses the old 7,700 kcal per kilogram (about 3,500 per pound) rule so you can see the intake implication.
Hall KD and colleagues showed that a sustained 10 kcal/day change leads to roughly a pound of eventual weight change, with about half in a year. The NIH Body Weight Planner models that curve. This page does not replace it. It shows why the linear calendar is optimistic.
A worked example
80 kg toward 74 kg at 0.4 kg/week is 15 weeks on paper. A 0.4 kg/week rate implies about 440 kcal/day using the old rule. Adaptive thermogenesis and a falling TDEE mean the same intake produces less loss by week 12. Budget extra weeks, or take a diet break and resume.
Choosing a weekly rate
About 0.5–1% of body weight per week suits most people. Faster looks brave in month one and fails in month three. If a rate requires an intake you cannot hold around normal meals, it is too fast.
At 80 kg, 0.5% is 0.4 kg/week — the default on this slider. 1% is 0.8 kg/week and will demand a gap most people cannot log honestly. The calendar looking shorter is not a benefit if the log dies in week three.
When this tool is the wrong tool
If the goal weight is not yours to pick — a clinician’s target, adolescence, pregnancy, or a history of disordered eating — do not use a web timeline. If you are already lean, small weekly rates still assume fat is the main thing lost, which is less true. General information, not medical advice.
If the implied daily gap from the old rule would put you on a clinically low intake, the weekly rate is too fast, not “more efficient.” Slow the slider. The deficit-size guide is the decision; this page is the calendar.
FAQ
Why is this slower than Instagram says?
Because those calendars use the linear rule and ignore the drop in expenditure. Half of a given intake change can take a year to show up fully.
What if I stall before the week count?
First blame water and logging. Then recalculate maintenance. Then consider a smaller cut or a break. Do not halve intake because a calendar felt rude.
Can I use this for gaining?
Not this UI — it estimates a loss timeline. For a surplus, measure maintenance and add a little, then watch the weekly average.
Should I trust the daily calorie gap?
Treat it as the 3,500 kcal/lb implication, not as a prescription. The NIH Body Weight Planner is the more honest curve if you want a model rather than a straight line.
Why not just show the NIH planner?
Because this page is a ceiling on optimism, not a research model. Use the Body Weight Planner when you want the curve. Use this slider when you want to see how fast is too fast.
Sources
- [1] Hall KD, Sacks G, et al. “Quantification of the effect of energy imbalance on bodyweight” (2011) — The Lancet 378:826–837 (PMID 21872751)
- [2] Body Weight Planner — National Institute of Diabetes and Digestive and Kidney Diseases (NIH)
General nutrition information, not medical advice. Calorie and macro targets are estimates — talk to a doctor or a registered dietitian before changing your diet, especially if you are pregnant, managing a health condition, or have a history of disordered eating.
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