Calorie Deficit Calculator
Estimate how many calories to eat each day to lose fat at the pace you choose, how far that is below your maintenance calories, and, if you add a goal weight, about how long it may take. The math runs in your browser: nothing you type is sent anywhere.
Your estimated deficit and timeline
Fill in the form and press Calculate to see your daily calorie estimate, your deficit below maintenance, the estimated weekly loss and, with a goal weight, the estimated time to reach it.
- Daily calorie estimate
- Deficit below maintenance
- Estimated loss
- Time to your goal weight
- Maintenance (TDEE)
This pace would go below the calculator's floor (1,200 kcal a day or 1.2 times your BMR, whichever is higher), so the estimate stops there and the loss is slower than the pace you chose. If the floor is at or above your maintenance, there is no deficit and no timeline. The floor is our own starting choice, not advice.
These are estimates, not medical or dietary advice. How we estimate, with sources
How a calorie deficit works
A calorie deficit is the gap between the energy you burn in a day (your TDEE, or maintenance calories) and the energy you eat. The calculator estimates your TDEE from the Mifflin-St Jeor equation and your training days, takes away the deficit for your pace, and converts it to weight with the common approximation of 7,700 kcal per kg.
A worked example: a 30-year-old man, 175 cm and 70 kg, training three days a week, has an estimated maintenance of 2,391 kcal a day. At the steady pace (about 0.5% of body weight a week) the estimate is 2,006 kcal, 385 below maintenance, or about 0.35 kg a week. To reach 65 kg, that is about 15 weeks.
How big a deficit?
The pace sets the size. Here are the calculator's estimates for each pace, for a 30-year-old man at 180 cm and 90 kg who trains four days a week (maintenance about 3,008 kcal a day).
Estimated rate of loss by pace (30-year-old man, 180 cm, 90 kg, four training days)
| Pace | Calories a day | Deficit (kcal) | Estimated loss (kg a week) |
|---|---|---|---|
| Slow (0.25%) | 2,761 | 247 | 0.22 |
| Steady (0.5%) | 2,513 | 495 | 0.45 |
| Faster (0.75%) | 2,266 | 742 | 0.67 |
| Fastest (1%) | 2,256 | 752 | 0.68 |
The fastest pace stops at the calculator's floor of 1,200 kcal or 1.2 times BMR, whichever is higher, so it is barely faster. When the floor holds, the result says so. These paces and the floor are our own starting choices, listed on the sources page, not advice.
Keeping muscle in a deficit
When you eat less, part of the weight you lose can be muscle. In a randomized trial of people training hard in a deficit, the group that ate more protein kept more lean mass and lost more fat. So the protein you eat and the lifting you keep doing matter as much as the size of the deficit.
Why your deficit should be re-estimated weekly
The 7,700 kcal per kg rule overstates weight loss over longer periods, and your energy use drops a little as you get lighter, so a fixed number drifts off over the weeks. The BodyMacros app compares what you logged with your weight trend every week and re-estimates your calories, with the reason in plain words.
What is a calorie deficit?
A calorie deficit means eating fewer calories than you burn, so your body makes up the difference from its stores, mostly fat. Its size is how many calories a day you are below your maintenance. A bigger deficit means faster estimated loss, but also less food each day.
How to eat in a calorie deficit
Start from an estimate like the one above, then log what you eat so you know whether you are near it. Keep your protein up and keep lifting, to help protect muscle. Weigh yourself a few times a week and look at the trend, not single days, before you change the number.
FAQ
How much weight will I lose with this deficit?
The calculator estimates it with the common approximation of 7,700 kcal per kg of weight. For example, 385 kcal a day below maintenance works out to about 0.35 kg a week. Real loss usually slows over time, because that approximation overstates long-term change and your energy use drops a little as you get lighter.
How many calories should I eat to lose weight?
Eat somewhat less than your maintenance calories (TDEE). At the steady pace, this calculator aims at about 0.5% of your body weight a week: for a 30-year-old man at 175 cm and 70 kg who trains three days, about 2,006 kcal a day. Treat it as a starting estimate and check it against your weekly trend.
Can I set a goal date?
You set a goal weight instead, and the calculator estimates how many weeks it may take at the pace you pick. To aim for a date, try the paces and see which timeline fits. Because real loss tends to slow over time, read the number as a rough estimate, not a deadline you have to meet.
How big a deficit is too big?
There is no single limit that fits everyone, so this calculator does not give one as advice. It never goes below 1,200 kcal a day or 1.2 times your BMR, whichever is higher, and its fastest pace is about 1% of body weight a week. Both are our own starting choices, listed on the sources page.
What is a calorie deficit?
It means eating fewer calories than your body burns in a day, so it uses its own stores, mostly fat, to make up the difference. The size of the deficit is how far below your maintenance calories you eat. This calculator estimates both your maintenance and a daily target for the pace you choose.
How do I start a calorie deficit?
Estimate your maintenance calories, pick a pace and eat close to the daily estimate. Logging your food shows whether you really are near it, and weighing yourself a few times a week shows the trend. If the trend does not move after two or three weeks, the estimate needs to change, which the app does for you.
Is a deficit of 250 calories a day good?
It is a small deficit. By the 7,700 kcal per kg approximation, 250 kcal a day is about 1,750 kcal a week, or roughly 0.23 kg. That is slow, which some people find easier to keep up. Whether it suits you depends on your size and goal; the calculator's slow pace shows a similar size.
Is a deficit of 500 calories a day a lot?
It depends on your size. 500 kcal a day is about 3,500 kcal a week, or roughly 0.45 kg by the 7,700 kcal per kg approximation. For a 90 kg person that is about 0.5% of body weight a week, the calculator's steady pace; for a 60 kg person it is closer to 0.75%, the faster pace.
What should I eat to be in a calorie deficit?
Any foods can fit, as long as the total stays near your estimate. For keeping muscle, protein matters most: this site estimates 1.6 g per kg of body weight a day while you lose fat. Logging what you eat in the BodyMacros app shows how much of your daily estimate each meal uses.
Can a calorie deficit target belly fat?
A calorie deficit lowers body fat overall; you cannot choose where it comes off. In one trial, six weeks of abdominal exercises did not reduce belly fat more than no abdominal exercises at all. So this calculator estimates your total calories, and where you lose fat first depends on your body.
Track this in the app
Log your food and your lifts in one place. Your estimates adjust each week to how you eat and train.
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