Enter the pounds you want to lose to calculate the calories you need to burn. A target of 1 pound corresponds to 3,500 calories.
Lbs to Calories Formula
Calories = Pounds × 3,500
Pounds = Calories ÷ 3,500
Pounds Lost = (Daily Deficit × Days) ÷ 3,500
- Calories — total energy deficit in kilocalories (Cal or kcal)
- Pounds — body weight change in lb
- Daily Deficit — Calories per day below maintenance
- Days — length of the deficit period
- 3,500 — Calories stored in roughly one pound of body fat
The 3,500 Cal per pound figure is an estimate based on the energy density of adipose tissue. Real weight changes also include water, glycogen, and lean tissue, and your maintenance Calories shift as you lose weight. Treat the result as a planning estimate, not a guarantee. For kg, the calculator converts using 1 lb = 0.45359237 kg. For kJ, it uses 1 Cal = 4.184 kJ.
Reference Tables
Use these to sanity-check pacing before you commit to a target.
| Weight Loss | Total Calorie Deficit | Kilojoules |
|---|---|---|
| 1 lb | 3,500 Cal | 14,644 kJ |
| 5 lb | 17,500 Cal | 73,220 kJ |
| 10 lb | 35,000 Cal | 146,440 kJ |
| 20 lb | 70,000 Cal | 292,880 kJ |
| 1 kg | 7,716 Cal | 32,283 kJ |
| Daily Deficit | Weekly Loss | Notes |
|---|---|---|
| 250 Cal | 0.5 lb | Slow, easy to maintain |
| 500 Cal | 1.0 lb | Most common target |
| 750 Cal | 1.5 lb | Faster, harder to sustain |
| 1,000 Cal | 2.0 lb | Aggressive; watch nutrition |
| 1,500 Cal | 3.0 lb | Medical supervision recommended |
Example and FAQ
Example: You want to lose 8 lb. Multiply 8 × 3,500 = 28,000 Cal. At a 500 Cal/day deficit, that takes 56 days, or about 8 weeks.
Is the 3,500 rule accurate? It is a useful approximation for short-term planning. Over months, metabolic adaptation slows the actual rate of loss, so progress usually trails the math.
Does this work for gaining weight? Yes. A 3,500 Cal surplus corresponds to about 1 lb gained, though more of that gain may be lean mass if you train and eat enough protein.
Why does my scale not match? Day-to-day weight fluctuates with water, sodium, glycogen, and digestion. Compare weekly averages instead of single readings.
Should I eat back exercise Calories? The calculator works on net deficit. If you log exercise as part of your deficit, do not also subtract it from intake, or you will double-count.
