Calorie Deficit Calculator
Find your daily calorie target for safe, steady weight loss
Your Daily Calorie Targets
Based on your inputs, here’s your personalized plan
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Understanding Your Calorie Deficit
To lose weight, you need to consistently consume fewer calories than your body burns. A deficit of 500 calories per day typically leads to about 0.5 kg (1.1 lbs) of weight loss per week, since roughly 7,700 calories corresponds to 1 kg (about 3,500 calories per pound) of body fat.
For healthy, sustainable weight loss, most health authorities advise not going below 1,200 calories per day for women or 1,500 calories per day for men without medical supervision.
Enter your details above and this calorie deficit calculator gives you a daily calorie target for weight loss, built from your Basal Metabolic Rate (BMR) and activity level rather than a generic one-size-fits-all number. What follows explains where that number comes from, how to use it safely, and where a lot of people go wrong with calorie deficits.
How This Calorie Deficit Calculator Works
The calculation runs in two steps. First, it estimates your Basal Metabolic Rate — the calories your body burns at complete rest just to keep your organs running — using the Mifflin-St Jeor equation, which is generally considered more accurate than older formulas like Harris-Benedict for most adults:
- Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
- Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
Second, your BMR is multiplied by an activity factor to get your Total Daily Energy Expenditure (TDEE) — your actual maintenance calories once daily movement and exercise are accounted for. Your calorie deficit target is then your TDEE minus the daily deficit needed to hit your chosen weekly weight loss rate.
Why the Calculator Won’t Let You Go Too Low
You may notice that very aggressive combinations (an older, less active person choosing “Extreme” weight loss) get capped rather than showing a dangerously low number. This isn’t a bug — it’s a safety floor. Eating below roughly 1,200 calories a day as a woman or 1,500 as a man, for an extended period, without medical guidance is associated with nutrient deficiencies, muscle loss, and a slower metabolism working against you rather than for you. If your result hits that floor, the honest fix is a milder weekly goal, not a workaround.
What Counts as a “Safe” Deficit
A 500-calorie daily deficit is the classic starting point because it lines up with losing about a pound a week — a pace most guidelines consider sustainable without excessive muscle loss or metabolic slowdown. Faster isn’t automatically better: a much larger deficit tends to increase muscle loss alongside fat loss, and it’s harder to stick to for more than a few weeks.
| Weekly Goal | Approx. Daily Deficit | Typical Timeline for 5 kg (11 lb) |
|---|---|---|
| Mild (0.25 kg/week) | ~275 cal | ~20 weeks |
| Moderate (0.5 kg/week) | ~550 cal | ~10 weeks |
| Fast (0.75 kg/week) | ~825 cal | ~7 weeks |
| Extreme (1 kg/week) | ~1,100 cal | ~5 weeks |
The “extreme” end of that table is where medical supervision genuinely matters — it’s achievable for some people short-term, but it’s also where the safety floor above is most likely to kick in.
Maintenance Calories vs. Deficit Calories
Your maintenance calorie number (what a maintenance calorie calculator gives you) is the baseline — it’s what keeps your weight stable, not what gets you to a goal. It’s still worth knowing on its own: if you’ve ever plateaued on a diet, your maintenance number recalculated at your new, lower weight explains why — as you lose weight, your TDEE drops too, which is why deficits need the occasional recheck rather than a single calculation that lasts forever.
Common Mistakes People Make With a Calorie Deficit
- Not recalculating as weight changes. A deficit set for your starting weight becomes a smaller deficit — or none at all — once you’ve lost 10+ kg, since your TDEE has dropped along with your body size.
- Underestimating food intake. Most people underreport what they eat, sometimes significantly, which quietly erases a deficit that looks correct on paper.
- Overestimating activity level. Picking “very active” because you go to the gym a few times a week, when your job and the rest of your day are sedentary, inflates your maintenance number and stalls progress.
- Chasing the scale daily. Water retention, sodium, and hormonal cycles move the number day to day far more than fat loss does — weekly averages tell the real story.
- Ignoring protein. A calorie deficit calculator gives you a total number, not a breakdown — pairing your target with adequate protein intake (a separate calculation from a macro calculator) matters for preserving muscle while losing fat.
Using the Goal Weight Timeline
The optional goal weight field above gives you a rough timeline rather than a promise — real weight loss isn’t perfectly linear, and it typically slows as you get closer to a lower body weight because your maintenance calories drop along the way. Treat the estimate as a planning tool, then recalculate every few weeks using your current weight for a more accurate read as you go.
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BMI Calculator TDEE Calculator Macro Calculator All Health CalculatorsFrequently Asked Questions
How many calories are in a pound of body fat?
Roughly 3,500 calories per pound, or about 7,700 calories per kilogram — which is the figure this calculator uses to convert your weekly weight loss goal into a daily calorie deficit. It’s a useful rule of thumb rather than an exact biological constant, since real-world weight loss also includes water and some lean tissue.
What’s the difference between this and a maintenance calorie calculator?
A maintenance calorie calculator only gives you the calories needed to hold your current weight steady (your TDEE). This tool starts from that same number, then subtracts the deficit needed for your chosen weekly weight loss rate — so your maintenance figure is shown alongside your actual target, not left out.
Is a 1,000-calorie-a-day deficit safe?
For most adults, a 1,000-calorie daily deficit is aggressive and often pushes total intake below the safe floor this calculator enforces (1,200 for women, 1,500 for men). It’s generally better suited to short-term, medically supervised plans than an ongoing approach — a 500–750 calorie deficit is more sustainable for most people.
Why did my target not change even though I selected a faster goal?
This happens when the faster goal would push your daily calories below the safety floor. The calculator caps your target at that floor rather than showing an unsafe number, which means selecting an even faster goal on top of an already-low maintenance calorie count won’t lower the number further.
Does this work as a calorie calculator for weight loss if I’m very active?
Yes — the activity multiplier scales your maintenance calories up for higher activity levels, so a very active person gets a proportionally higher target than someone sedentary at the same weight, age, and height, before the same deficit is applied on top.