Free calorie deficit calculator
Answer a few questions and you get one number: the calories to eat each day to reach your goal weight at a pace you can actually hold. It uses the Mifflin-St Jeor equation for your daily burn, subtracts a deficit sized to your goal, and stops at a safe floor rather than coaching a target no one should eat. Free, no account, about a minute.
Hi, I’m your calorie coach
I'll ask a few quick questions and find the calorie deficit that fits your life.
How this calculator works
Three steps, none of them secret. It is the same code the MyCalorieCoach app runs, so the number here and the number in the app cannot disagree.
1. Your basal metabolic rate (BMR)
What you would burn lying still all day. The Mifflin-St Jeor equation is the most accurate of the common ones:
- Men: (10 x weight in kg) + (6.25 x height in cm) - (5 x age) + 5
- Women: (10 x weight in kg) + (6.25 x height in cm) - (5 x age) - 161
2. Your total daily energy expenditure (TDEE)
BMR multiplied by how much you move. You eat against this number, never against BMR.
| Activity level | Roughly | Multiplier |
|---|---|---|
| Sedentary | Desk job, little deliberate exercise | 1.2 |
| Lightly active | On your feet some of the day, or one to three workouts a week | 1.375 |
| Active | Three to five workouts a week, or an active job | 1.55 |
| Very active | Hard training most days, or heavy physical work | 1.725 |
3. Your deficit
About 7,700 kcal is stored in a kilogram of body fat, so a deficit of 1,100 kcal a day works out at roughly 1 kg a week. The calculator sizes the deficit from the distance to your goal and the pace you pick, and caps the pace at 0.7 kg a week. Push past that and more of what you lose is muscle, for a diet you are less likely to still be doing in six weeks.
There is also a floor: 1,200 kcal a day for women and 1,500 for men. If your goal would need a target below it, the calculator holds the target at the floor and lengthens the timeline instead.
A worked example
A 34-year-old woman, 168 cm, 78 kg, desk job, aiming for 70 kg.
- BMR = (10 x 78) + (6.25 x 168) - (5 x 34) - 161 = 1,499 kcal
- TDEE = 1,499 x 1.2 = 1,799 kcal
- Losing 8 kg at a steady 0.5 kg a week takes 16 weeks. That is a deficit of 550 kcal a day.
- Daily target = 1,799 - 550 = about 1,250 kcal
That sits just above the 1200 kcal floor, so it stands. If the sums had landed below it, the calculator would hold the target at the floor and stretch the timeline instead of coaching a target that is not safe to eat.
What most calorie calculators leave out
Every calculator can do the arithmetic above. What none of them ask is the question that decides whether you stick to the number: what are you not willing to give up?
A deficit is a total across a day and a week. It is not a rule about any one food. If the morning coffee stays, the Friday pizza stays, and the rice on the plate stays, the deficit simply has to come from somewhere else. That is a solvable problem, and it is the one this calculator asks about while it works, because a target you abandon in week three is worth less than a slightly slower one you keep.
Common questions
- What is a calorie deficit calculator?
- A calorie deficit calculator works out how many calories you burn in a day, then subtracts enough to reach your goal weight at a pace you can hold. It needs your sex, age, height, weight, activity level and goal weight. What it hands back is a single number: the calories to eat each day.
- How many calories should I eat to lose weight?
- Most people land between 1,400 and 2,200 kcal a day, but the useful answer is personal: it is your total daily energy expenditure minus a deficit. A deficit of 300 to 700 kcal a day loses roughly 0.3 to 0.7 kg a week, which is the range that protects muscle and is still liveable.
- How does this calculator work out my number?
- It uses the Mifflin-St Jeor equation for your basal metabolic rate, multiplies by an activity factor for your total daily burn, then subtracts a daily deficit sized to your goal weight and the pace you pick. 7700 kcal is treated as roughly 1 kg of body fat. It is the same maths the MyCalorieCoach app runs, from the same shared code.
- Is a 500 calorie deficit a day enough?
- A 500 kcal daily deficit is about 0.45 kg a week, which is a good default for most people. Bigger is not better: past about 0.7 kg a week you start losing more muscle, feel worse, and are far more likely to stop.
- How accurate is a calorie calculator?
- Mifflin-St Jeor is the most accurate of the common equations, and it is still an estimate. Individual metabolisms vary by roughly 10% either way. So treat the number as a starting point and adjust it against what the scale actually does over two to three weeks, which is the part the coach does for you.
- What is the difference between BMR and TDEE?
- BMR is what you would burn lying still all day. TDEE is BMR plus everything else: moving, working, training, and digesting food. You eat against TDEE, never against BMR.
- Why does the calculator refuse to go below a certain number?
- There is a floor: 1200 kcal a day for women and 1500 for men. Below that it gets hard to hit your protein and micronutrients, and the weight you lose is more likely to be muscle. If your goal needs a target under the floor, the calculator holds the target and lengthens the timeline instead.
- Do I have to give up the food I love to be in a deficit?
- No, and this is the part most calculators get wrong. A deficit is a total across a day and a week, not a rule about any one food. Name the things you will not cut, and the deficit gets found somewhere else. That is the whole idea behind the coach this calculator comes from.
- Should I eat back the calories I burn exercising?
- Not usually. The activity multiplier already includes your typical week of training, so eating back your watch estimate on top double counts it. If your training genuinely changes, move up an activity level instead.
- Is this calculator free?
- Yes, completely, with no account and no card. The app it comes from is a paid subscription with a 14-day free trial.