Weight Loss Calculator
The daily calories to reach your goal weight and a projected finish date — from your TDEE and a loss rate you choose, with honest safety limits built in.
Losing weight is an energy-budget problem: eat consistently below what you burn and the difference comes out of stored fat. This calculator does the budgeting — your maintenance calories, the daily target for the loss rate you choose, and the date you’d reach your goal — with the safety rails that most calculators skip. If you arrived looking for a calorie calculator for weight loss — or a calorie deficit calculator for weight loss — you’re in the right place: the daily target it returns is exactly that number, with a finish date attached. Enter your stats in kilograms or pounds; the calculator converts automatically.
The math, in the open
- Maintenance (TDEE): Mifflin-St Jeor BMR from your sex, age, height, and weight, times an activity factor — the same figure our TDEE calculator works out step by step.
- The deficit: a kilogram of body fat stores roughly 7,700 kcal, so each 0.5 kg/week of planned loss needs about a 550 kcal daily deficit.
- The timeline: total weight to lose ÷ weekly rate = weeks; the calculator dates it on the calendar and shows all four standard rates side by side.
The safety rails
Two warnings are built in, because an honest tool should refuse to pretend everything is fine:
- Aggressive pace — rates above ~1% of body weight per week accelerate muscle loss and rarely hold. Guidelines favor about 0.5–1 kg (1–2 lb) weekly.
- Below the floor — if your target drops under 1,200 kcal (women) / 1,500 kcal (men), the calculator says so. Below those intakes it’s hard to cover protein and micronutrient needs without supervision; a slower rate or more daily movement is the better lever.
Tracking your weight-loss percentage
Sometimes the useful figure isn’t calories at all — it’s how far you’ve come as a percentage of where you started. The maths is simple:
weight lost ÷ starting weight × 100
So dropping from 90 kg to 81 kg (198 lb to 178 lb) is a 9 kg (about 20 lb) loss, or 10% of your starting body weight — and that 5–10% band is exactly where clinical guidelines link weight loss to real improvements in blood pressure, blood sugar and cholesterol. Percentages also let you compare progress fairly between people of very different sizes, which is why programmes and studies tend to report them.
Why the scale won’t cooperate weekly
Kevin Hall’s modeling work (see references) showed the old “3,500 calories = a pound, forever” rule overstates long-term loss: as you shrink, your maintenance shrinks too, so a fixed intake produces slowing loss — not a straight line. Practical upshot: weigh daily, judge by the weekly average, expect a fast watery first week, and recalculate your target every few kilograms. Consistency over months, not perfection over days, is the entire game. To set the actual daily target and its protein-carb-fat split, hand off to the calorie calculator and the macro calculator.
Frequently asked questions
How does the weight loss calculator work?
It estimates your maintenance calories (Mifflin-St Jeor BMR × activity), then subtracts the daily deficit for your chosen rate — about 1,100 kcal/day per kilogram per week, from the ~7,700 kcal stored in a kilogram of body fat. The result is a daily calorie target and a projected date you reach your goal.
How do I calculate weight loss percentage?
Divide the weight you've lost by your starting weight, then multiply by 100. For example, losing 9 kg (about 20 lb) from a 90 kg (198 lb) start is 9 ÷ 90 × 100 = 10%. A loss of 5–10% of your starting weight is the point at which health markers like blood pressure and blood sugar typically start to improve.
How do I calculate macros for weight loss?
Start with the daily calorie target this calculator gives you, then split it: protein first — roughly 1.6 g per kilogram (0.7 g per pound) of body weight a day helps protect muscle in a deficit — fat at a moderate share of calories, and carbohydrates fill the rest. Our macro calculator does the split for you from the same calorie target.
How fast should I lose weight?
Mainstream guidance is about 0.5–1 kg (1–2 lb) per week, or up to about 1% of body weight weekly. Faster than that loses more muscle and water, is harder to sustain, and rebounds more often. The calculator flags rates above 1% of your body weight as aggressive.
Why shouldn't I just eat as little as possible?
Below roughly 1,200 kcal/day for women or 1,500 for men it becomes very difficult to get adequate protein and micronutrients, and adherence collapses. The calculator warns when a chosen rate pushes your target under those floors — pick a slower rate or add activity instead.
Will the projected date be exact?
No — treat it as a trajectory, not a promise. Early loss includes water weight, metabolism adapts slightly as you get lighter, and life happens. Recalculate every few weeks at your new weight; the finish date will firm up as you go.