Health

Calorie Deficit Calculator

Find the daily calorie target that matches your weight loss goal, with safe-floor guardrails. Free and instant.

Starting point

I know my TDEE Calculate it for me

TDEE (kcal/day)

Current weight (kg)

Weight loss per week

0.5 kg / 1 lb per week is the recommended sustainable rate.

Rate unit

kg / week lb / week

Target weight (kg)

Optional. Used to estimate weeks to goal.

Daily target

— kcal/day

Enter your data to see the target

TDEE —

Daily deficit —

Weeks to goal —

What is a calorie deficit?

A calorie deficit is the gap between the calories you burn each day (your TDEE — total daily energy expenditure) and the calories you eat. When you consistently eat less than you burn, your body taps into stored energy — primarily fat — to make up the difference, and you lose weight over time. The classic rule of thumb is that 1 kg of body fat ≈ 7,700 kcal (or ~3,500 kcal per pound). To lose 0.5 kg per week, you need a daily deficit of about 550 kcal sustained over 7 days. That math is a simplification — actual fat loss depends on protein intake, training, sleep, NEAT (non-exercise activity), and metabolic adaptation — but it's a useful starting point. Two important caveats: deficits don't have to be aggressive to work, and bigger isn't better. Going too low triggers hunger spikes, muscle loss, hormonal disruption, and a high probability of rebound. Most evidence supports a 10-20% deficit below maintenance with adequate protein and progressive resistance training. This calculator is informational; talk to a registered dietitian or doctor before making major changes.

How to use this calculator

1. If you already know your TDEE (from a tracker or our TDEE calculator), pick "I know my TDEE." Otherwise choose "Calculate it for me" and we'll run Mifflin-St Jeor for you. 2. Pick a weight-loss rate. 0.5 kg / 1 lb per week is the standard recommendation; faster rates work short-term but increase muscle loss and rebound risk. 3. Optionally enter a target weight to see weeks-to-goal. The result is your suggested daily intake. We cap it at a safe minimum (1,500 kcal men / 1,200 kcal women) — if you hit the cap, slow your target rate.

How the daily target is calculated

Mifflin-St Jeor BMR (when computed for you): BMR = 10·weight + 6.25·height − 5·age + (5 if male else −161). TDEE = BMR × activity factor. Daily deficit = (rate × 7700) ÷ 7 for kg, or (rate × 3500) ÷ 7 for lb. Daily target = TDEE − daily deficit, with a floor at 1,500 kcal (men) or 1,200 kcal (women). Weeks to goal = (current − target) ÷ rate.

Sustainable rates and what they cost

Faster isn't always better. The table below shows weekly rates, the daily deficit they imply, and the typical experience.

Rate	Daily deficit	Notes
0.25 kg / 0.5 lb	~ 275 kcal	Easy to maintain, minimal muscle loss
0.5 kg / 1 lb	~ 550 kcal	Recommended baseline
0.75 kg / 1.5 lb	~ 825 kcal	Use only short-term, with high protein
1 kg / 2 lb	~ 1100 kcal	Not sustainable for most people

Frequently asked questions

Is the 7,700 kcal/kg rule accurate?

It's a simplification. Real fat loss varies because the body adapts (NEAT drops, BMR shifts, water/glycogen changes mask scale weight). Treat it as a starting estimate and adjust based on 2-3 weeks of real data.

Why is there a minimum calorie floor?

Going below ~1,200 kcal (women) or 1,500 kcal (men) for prolonged periods makes it hard to meet protein, vitamin and mineral needs, and increases risk of muscle loss, fatigue, hair loss and binge cycles. Larger people may need higher floors.

How fast should I lose weight?

Most evidence supports 0.5-1% of body weight per week. For an 80 kg person that's roughly 0.4-0.8 kg/week. Faster rates work but cost more in muscle loss, mood, training quality and adherence.

Do I have to count calories every day forever?

No. Tracking for a few weeks is the fastest way to learn portion sizes and food density. Once you've calibrated, many people maintain results with simple habits — protein at every meal, mostly whole foods, and weekly weight checks.

Why isn't the scale moving even though I'm in a deficit?

Water and glycogen swings can mask 2-3 kg of fat loss for weeks. Sodium, menstrual cycle, training volume and stress all affect water. Use a 7-day rolling average and look for a trend over 3-4 weeks before adjusting.

Is this medical advice?

No. It's a general estimation tool. If you have a medical condition, take medication, are pregnant, breastfeeding, or have a history of disordered eating, please work with a doctor or registered dietitian.

Calorie Deficit Calculator