Calorie deficit calculator
A calorie deficit is the gap between what you burn and what you eat. This calculator works out both, proposes a sustainable rate, and holds a hard line below which cutting further costs more than it gives.
Calculate
The values below are an example — change them to yours and the result updates instantly.
Past 1% a week, what rises is muscle loss — not the rate at which fat comes off.
Result
1,850 kcal
Eat this much a day to lose weight
- Your daily calorie needs (TDEE)
- 2,230 kcal
- Daily deficit
- 380 kcal
- Expected rate
- 0.35 kg / week
- Resting metabolic rate (BMR)
- 1,440 kcal
Where a safe deficit comes from
To lose weight you have to take in less energy than you spend. The calculator works out your total daily energy expenditure first, then subtracts whatever the rate you picked implies. The conversion is simple enough: a kilogram of body fat holds roughly 7,700 kcal, so losing half a kilo a week needs a deficit of about 550 kcal a day.
That is an approximation, and it is worth knowing which way it errs. Your body responds to a deficit — resting expenditure drops, spontaneous movement falls off, and the composition of what you lose shifts. So the real rate after a few weeks is usually a little slower than the arithmetic predicts. That is normal, and it does not mean you are doing anything wrong.
Why the calculator will not go below your BMR
Your basal metabolic rate is the energy your body needs for your heart, your breathing, your temperature and your brain. Eating below it for any length of time is not faster weight loss; it is running basic functions at a discount, and the body reads it exactly the way that sounds.
The consequences are predictable: noticeable muscle loss alongside fat, persistent fatigue, worse sleep, poor concentration, and in women frequently a disrupted cycle. On top of that comes escalating hunger, which sooner or later ends in a run of make-up days. So this calculator treats BMR as a hard floor rather than a suggestion. The popular “1,200 kcal” figure is no use here — it is a constant applied to everyone, whereas BMR is the same idea computed for the actual person in front of it.
What to do when the scale stops moving
Stalling for two or three weeks after a few months in a deficit is normal, and most of the time it is not a stall in progress at all — it is water. Bodyweight can move a kilo and a half overnight on salt, your cycle, glycogen after training, or simple constipation. Weighing once a week at the same time and reading the four-week average tells you far more than any single morning does.
If the average genuinely has not moved after a month, you have two sensible options. Add movement — ideally daily movement rather than another training session. Or take off 100–150 kcal, no more. There is a third option nobody mentions that is often the right one: spend two weeks eating at maintenance and return to the deficit afterwards. A deficit does not have to be uninterrupted to work.
Common questions
How big a calorie deficit is safe?
Usually ten to twenty percent below your total daily energy expenditure, which works out at roughly 0.25–0.5 percent of bodyweight a week. At a 2,000 kcal requirement that means eating 1,600–1,800 kcal a day. A deficit that size lets most of what you lose be fat rather than muscle, leaves your energy and sleep intact, and — the part that decides the outcome in practice — is one you can hold for several months. Do not go below your own basal metabolic rate, even briefly.
Does a bigger deficit mean faster weight loss?
Only up to a point, and not proportionally. Doubling the deficit does not double the rate at which fat comes off, but it does clearly increase the share of muscle in what you lose. The costs that never show on the scale rise too: worse sleep, falling strength, sharper hunger, and a much better chance of abandoning the plan inside three weeks. A slower deficit you keep for six months beats an aggressive one you keep for one.
How many calories a day to lose 5 kg?
That depends on the rate, not on the goal. Five kilos at 0.5 percent of bodyweight a week takes someone weighing 70 kg about four months — and throughout it you eat the same amount the calculator shows. A target weight does not change the daily calorie figure; it only changes how long you hold it. Recalculate after every 3–4 kilos lost, though: a lighter body spends less energy.
How do I know whether I am actually hitting the deficit?
That is the real question, because food-diary research consistently finds people underestimate their intake, often by several hundred calories a day and entirely unintentionally. Olivka counts your food in a chat: send a photo of the meal, a voice note, or a single sentence on WhatsApp, Messenger, Telegram, or Instagram and you get calories, macros and the day's running total back in seconds. Nothing to install and no account to create.
Sources
- Mifflin MD et al., “A new predictive equation for resting energy expenditure in healthy individuals”, The American Journal of Clinical Nutrition, 1990
- Hall KD, “What is the required energy deficit per unit weight loss?”, International Journal of Obesity, 2008 — on the limits of the 7,700 kcal rule
- Calorie calculator — your daily energy needs
- How Olivka counts calories — methodology and data sources
A deficit only works if the counting is honest.
Olivka totals your day in the background. Send a photo or one sentence and she works the rest out.
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Last updated: 2026-08-20