AnyTool
Your files never leave your device. All processing happens locally in your browser.

How many calories should I eat per day to lose or gain weight?

Enter your sex, age, height, weight and activity level into AnyTool Calorie Calculator in metric (cm / kg) or imperial (ft·in / lb). It estimates your maintenance calories (TDEE) with the Mifflin-St Jeor equation, then shows a rate table of calories per day to lose or gain weight at 0.25, 0.5, 0.75 and 1.0 kg per week (or 0.5–2 lb), each flagged if it would dip below a safe minimum intake. Add a target weight and it projects how many weeks it takes and roughly which date. Everything runs in your browser — nothing is uploaded.

  • Maintenance calories (TDEE) = the calories to stay the same weight
  • Lose 0.5 kg/week ≈ a 550 kcal/day deficit; 1 kg/week ≈ 1,100 kcal/day
  • 1 kg of body fat ≈ 7,700 kcal (1 lb ≈ 3,500 kcal)
  • Safe-intake floor: 1,500 kcal/day (men), 1,200 kcal/day (women)
  • Target-weight timeline with a projected date — 100% in your browser

What is

Calorie Deficit and Surplus

A calorie deficit is eating fewer calories than your maintenance (TDEE), which leads to weight loss; a surplus is eating more, which leads to weight gain. Because about 7,700 kcal equal one kilogram of body fat (3,500 kcal per pound), a deficit of roughly 550 kcal/day loses about 0.5 kg per week. A calorie calculator estimates maintenance from sex, age, height, weight and activity, then applies a chosen deficit or surplus to give a daily calorie target and a projected timeline to a goal weight.

Calculators

Related terms

Maintenance calories (TDEE)Calorie deficitSafe weight-loss rateMifflin-St Jeor equation

Frequently Asked Questions

About 7,700 kcal equal a kilogram of fat and 3,500 a pound, so a 550 kcal/day deficit loses about 0.5 kg/week and a 1,000 kcal/day deficit about 0.9 kg (2 lb)/week.

One kilogram of body fat stores roughly 7,700 kcal and one pound about 3,500, so the daily deficit is the weekly target spread over seven days: losing 0.5 kg per week needs around 550 kcal/day below maintenance, and 1 kg per week needs about 1,100 kcal/day. AnyTool builds a full rate table for 0.25–1.0 kg per week (or 0.5–2 lb) and applies a safe minimum-intake floor so it never recommends eating too little.

About 0.5–1 % of your body weight per week, which is roughly 0.5–1 kg (1–2 lb) for most people. Faster loss is rarely sustainable.

Health guidance puts sustainable weight loss at about 0.5 to 1 percent of body weight per week — roughly half a kilogram to a kilogram (one to two pounds) for most adults. Larger deficits can slow metabolism and cause muscle loss, and going below about 1,500 kcal/day for men or 1,200 for women is not advised without supervision. AnyTool flags rates above 1 %/week as aggressive and floors every deficit at the safe minimum intake.

Divide the calories you need to lose by your daily deficit. AnyTool does this for you and shows the weeks plus a projected calendar date.

The straight-line estimate is the total energy gap (weight change × 7,700 kcal/kg or 3,500 kcal/lb) divided by your daily deficit, converted to weeks. Enter a target weight and AnyTool projects the number of weeks at your chosen rate and a calendar date counted from today. Real loss is not linear, though — as you get lighter your maintenance falls and progress slows, so the later weeks usually take longer than the projection.

It is an estimate accurate to about ±10 %, and nothing is uploaded — all the math runs in your browser.

Maintenance calories rely on a predictive equation and an activity multiplier, both population averages, so the true figure can vary by roughly ±10 %, and the timeline assumes a steady fat energy density that real metabolism does not quite follow. Use the result as a starting point, track your weight for 2–3 weeks and adjust. AnyTool Calorie Calculator runs entirely in your browser, so your sex, age, height and weight are never sent to a server and the page works offline.

Detailed Explanation

Methodology

How the Calorie Calculator Works

AnyTool Calorie Calculator first estimates maintenance calories (Total Daily Energy Expenditure) in the browser. It computes Basal Metabolic Rate with the Mifflin-St Jeor equation — 10 × weight(kg) + 6.25 × height(cm) − 5 × age, then +5 for men or −161 for women — and multiplies it by an activity factor from 1.2 (sedentary) to 1.9 (extra active). It then converts goals into calories using the standard energy density of body tissue: about 7,700 kcal per kilogram of fat and 3,500 per pound. The daily deficit or surplus for a chosen weekly rate is (weekly change × 7,700) ÷ 7, so losing 0.5 kg/week needs roughly 550 kcal/day below maintenance. All arithmetic is pure client-side JavaScript shared with a unit-tested engine.

  • Maintenance (TDEE) = Mifflin-St Jeor BMR × activity factor (1.2–1.9)
  • 1 kg of body fat ≈ 7,700 kcal; 1 lb ≈ 3,500 kcal
  • Daily delta = (weekly change × 7,700) ÷ 7
  • −0.5 kg/week ≈ −550 kcal/day; −1 kg/week ≈ −1,100 kcal/day
  • All math is client-side JavaScript — no server round-trip
How It Works

Safe Rate Table and Target-Weight Timeline

Rather than a single number, the tool shows a rate table — calories per day to lose or gain weight at 0.25, 0.5, 0.75 and 1.0 kg per week (or the 0.5–2 lb equivalents) — colour-coded by direction. Every deficit is floored at a conservative minimum intake of 1,500 kcal/day for men and 1,200 for women so the table never recommends eating too little, and rates faster than about 1 % of body weight per week are flagged as aggressive. Enter a target weight and the page projects a timeline: the energy gap (weight change × 7,700 kcal/kg) divided by the chosen daily deficit gives the number of weeks, and the page adds those days to today’s date for a projected calendar date. The pure engine returns weeks and days only; the page supplies the current date, keeping the calculation deterministic.

  • Rate table: 0.25–1.0 kg/week or 0.5–2 lb/week, kcal/day each
  • Deficits floored at 1,500 kcal (men) / 1,200 kcal (women)
  • Rates above ~1 % body-weight/week flagged as aggressive
  • Timeline = energy gap ÷ daily deficit, in weeks
  • Projected date = today + days (date computed on the page)
Limitations

Estimates Are Accurate to About ±10 % and Loss Is Not Linear

Maintenance calories come from a predictive equation and an activity multiplier, both population averages, so the true figure can differ by roughly ±10 %. The timeline assumes a constant 7,700 kcal/kg and a fixed deficit, but real weight loss slows over time: as body weight falls, maintenance falls with it and metabolism adapts, so later weeks usually take longer than the straight-line projection. Sustainable change is about 0.5–1 % of body weight per week — faster loss is rarely kept off. The calculator therefore frames its numbers as a starting point: track weight for 2–3 weeks and adjust by 100–200 kcal from real results. It is general information, not medical or nutritional advice, and recommends consulting a clinician or dietitian, especially during pregnancy, illness or with a history of disordered eating.

  • Maintenance estimate accurate to roughly ±10 %
  • Weight loss is not linear — maintenance falls as you get lighter
  • Sustainable rate is about 0.5–1 % of body weight per week
  • Track weight 2–3 weeks and adjust by 100–200 kcal
  • Not medical or nutritional advice
Privacy & Security

Privacy and Offline Use

Because all computation runs in the browser, your sex, age, height, weight, activity level and target weight are never sent to a server, there is no account or tracking, and the page works offline after first load. The calculator shares a unit-tested calorie engine with the BMR tool, so the two agree to the calorie and the behaviour is consistent and verifiable.

Calorie planning: in-browser (AnyTool) vs typical online calorie calculators
CapabilityAnyToolTypical online calculators
ProcessingRuns in your browserOften server-side
UnitsMetric and imperial, liveUsually one at a time
Goal ratesTable of 0.25–1.0 kg/week with kcal eachOften one fixed deficit
Safe floorEnforced (1,500/1,200 kcal) and flaggedFrequently ignored
Target timelineWeeks + a projected dateOften omitted
HonestyStates ±10 % and non-linear loss plainlyRarely noted
Works offlineYes (PWA)No
Cost / signupFree, no signupOften ad-heavy or gated

AnyTool computes maintenance, every goal rate and the timeline locally and uploads nothing.