Calorie Deficit Calculator
Choose how fast you want to lose, and see the daily calorie number behind it — with a timeline that accounts for the part most calculators skip.
How the deficit is calculated
The calculator starts with your maintenance calories — your TDEE, estimated from the Mifflin–St Jeor equation and your activity level — and subtracts the daily gap that produces the rate of loss you picked. The conversion uses the classic figure of about 3,500 calories per pound of body fat:
| Rate of loss | Daily deficit | Weekly deficit |
|---|---|---|
| 0.5 lb (0.23 kg) a week | 250 cal | 1,750 cal |
| 1 lb (0.45 kg) a week | 500 cal | 3,500 cal |
| 1.5 lb (0.68 kg) a week | 750 cal | 5,250 cal |
| 2 lb (0.9 kg) a week | 1,000 cal | 7,000 cal |
Picking a rate you will still be running in three months
Faster is not better if it ends in a binge. A useful rule of thumb is to keep weekly loss around 0.5–1% of body weight: someone at 200 lb can comfortably aim for 1–2 lb a week, while someone at 140 lb should look at 0.5–1 lb. The heavier you are, the more aggressive you can be safely; the leaner you get, the more a large deficit costs you in muscle and energy.
There are also two ways to open the gap, and only one of them involves eating less. Adding 8,000 steps a day is worth roughly 250–400 calories for most people — the same as one of the rows above, but with food left on the plate. Splitting the deficit between the two sides is almost always more comfortable than taking it all from the fork.
Why the timeline is a range, not a date
The projection in the calculator assumes a constant deficit, and reality does not cooperate. As you lose weight your body burns fewer calories, so the same daily intake produces a smaller gap each month. Add water-weight noise from sodium, glycogen, and hormones, and the scale can sit still for two weeks while fat loss continues underneath. Recalculate every 10–15 lb (5–7 kg) lost and judge progress on a weekly average, never on a single morning.
Protecting muscle while the weight comes off
The goal is losing fat, not just mass. Two things do most of the work here: enough protein — generally 1.6–2.2 g per kg of body weight, which the macro calculator will size for you — and resistance training two or three times a week to give your body a reason to keep the muscle it has. Building meals around high-protein staples like Greek yogurt, eggs, and salmon makes hitting that target far less of a maths exercise.
The part that actually decides the outcome
A deficit you cannot see is a deficit you cannot trust. Studies of self-reported food intake find people routinely undercount by 20–40% — more than enough to erase a 500-calorie plan without anyone noticing. Whether you weigh food, estimate portions with the methods in our guide to counting calories without a scale, or photograph the plate and let an app do it, the requirement is the same: a record honest enough to act on. Our calorie database is a good place to memorise the numbers for the foods you eat every week.
A number is only useful if you hit it
A deficit only exists if the logging is honest. Cibo reads your meal from a photo and logs calories and macros in seconds, which is what keeps the untracked bites from quietly closing the gap.
Download on theApp StoreFrequently asked
What is a calorie deficit?
A calorie deficit is the gap between the calories you burn and the calories you eat. Hold that gap open over time and your body makes up the difference from stored energy, most of which is body fat. It is the one mechanism every successful diet has in common, regardless of what it calls itself.
How big should my calorie deficit be?
For most people, 500 calories a day — roughly a pound a week — is the sweet spot between visible progress and being able to stick with it. Smaller deficits of 250 a day suit people with less to lose or who want to protect training performance. Deficits above 1,000 a day get hard to sustain and increase muscle loss unless protein and resistance training are dialled in.
Is 1,200 calories a day safe?
1,200 calories is the commonly cited floor for women and 1,500 for men, and even those are low enough that hitting your vitamin and protein needs takes deliberate planning. If the calculator pushes your target under those numbers, the better move is a slower rate of loss or more daily movement rather than eating less. Very low calorie diets belong under medical supervision.
Why did my weight loss stall even though I am in a deficit?
Three usual suspects. First, the deficit shrank: a lighter body burns fewer calories, so the target that worked at the start no longer produces a gap. Second, intake crept up — portions drift, and unlogged bites add up faster than people expect. Third, it is water, not fat: sodium, stress, and the menstrual cycle can mask several weeks of real loss on the scale. If the weekly average has not moved in three weeks, recalculate at your new weight and tighten the logging.
Is the 3,500-calories-per-pound rule accurate?
It is a good planning approximation, not a physical law. The figure comes from the energy density of body fat, but real weight loss also includes water and some lean tissue, and your metabolism adapts as you get lighter. In practice the rule predicts the first few weeks well and gets progressively more optimistic after that — which is why this calculator says to expect the pace to slow.
Not medical advice. Cibo is a nutrition-awareness tool, not a medical device. Read the full disclaimer.