Losing 1 kg of body fat takes a deficit of roughly 7,700 kcal. Exercise alone works slowly; combined with a moderate diet deficit the time shortens a lot. A safe pace is about 0.5–1 kg (1–2 lb) per week.
How to use the Weight Loss by Exercise Calculator
- Current weight
- Target weight
- Activity
- Custom MET
- Exercise time per session
- Sessions per week
- Daily diet deficit (kcal)
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Enter your current and target weight, the activity, minutes per session, sessions per week and any daily calorie deficit from your diet.
Inputs explained
| Field | What to enter |
|---|---|
| Current weight | Units: kg, lb |
| Target weight | Units: kg, lb |
| Activity | Choose one: Aerobics, general, Baseball / softball, Basketball, game, Billiards … |
| Custom MET | A number |
| Exercise time per session | Units: min, h |
| Sessions per week | A number |
| Daily diet deficit (kcal) | A number |
What each result means
- Total weekly deficit = [Calories burned per week by exercise] + 7×[Daily diet deficit (kcal)]
- Estimated time to target = ([Current weight] – [Target weight])×7700÷[Total weekly deficit]
- Weight loss per week = [Total weekly deficit]÷7700
Example values
How the main result changes when Current weight changes and everything else stays at the example values above:
| Current weight (kg) | Estimated time to target (weeks) |
|---|---|
| 45 | -77.2 |
| 67.5 | -23 |
| 90 | 15.8 |
| 112.5 | 44.9 |
| 135 | 67.6 |
| 180 | 100.6 |
Formula
Weekly deficit = sessions × MET × 3.5 × kg ÷ 200 × minutes + 7 × daily diet deficit, weeks = (current − target) × 7,700 ÷ weekly deficit
Worked example
Inputs — Current weight: 90 kg; Target weight: 80 kg; Activity: Running, 10 km/h (6.2 mph); Exercise time per session: 45 min; Sessions per week: 4; Daily diet deficit (kcal): 300.
Results — Calories burned per week by exercise = 2,778 kcal; Total weekly deficit = 4,878 kcal; Estimated time to target = 15.8 weeks; Weight loss per week = 0.634 kg; Pace = Healthy pace.
Key terms
- Calorie deficit
- Burning more energy than you eat.
Frequently asked questions
How long does it take to lose 1 kg?
About 7,700 kcal of deficit – e.g. 500 kcal/day for 2 weeks.
Is exercise alone enough?
It helps, but most people need diet changes too.
Will the rate stay the same?
It slows as you get lighter; adjust your plan over time.
What is a safe rate?
About 0.5–1 kg (1–2 lb) per week.