Adaptive weight loss timeline
Your maintenance calories drop as you lose weight. We model that week by week instead of using the flat 3,500 calorie rule that overpromises.
Free weight loss planner · kg or lb
Calorie Deficit Calculator
Find out how many calories to eat to lose weight, how big a deficit is safe for you, and the date you could reach your goal. Your plan updates week by week as your weight drops, so the numbers stay realistic.
- No sign-up
- Adaptive goal date
- Built-in safety checks
- Macros included
Calculate your calorie deficit
Your week-by-week weight loss projection
- Projected weight
- Goal weight
Milestones
| Week | Date | Weight | Eat |
|---|
Compare deficit paces
| Pace | Calories/day | Deficit | Goal date |
|---|
What is a calorie deficit?
A calorie deficit means eating fewer calories than your body burns in a day. When intake falls below your total daily energy expenditure (TDEE), your body covers the gap from stored energy, mostly body fat. Keep a moderate deficit going for weeks and the scale moves down in a predictable way.
The hard part is choosing the right number. Cut too little and progress stalls. Cut too much and you lose muscle, feel drained, and usually quit. This calorie deficit calculator finds your maintenance calories, subtracts a deficit that matches your chosen pace, and shows exactly how many calories to eat to lose weight without crossing into unsafe territory.
How the calorie deficit calculator works
- BMR (Mifflin-St Jeor):
10 × kg + 6.25 × cm − 5 × age + 5for men,− 161instead of+ 5for women. - BMR (Katch-McArdle, with body fat):
370 + 21.6 × lean mass in kg - Maintenance calories:
TDEE = BMR × activity factor(1.2 to 1.9) - Daily target:
TDEE − deficit, where 1 kg of body fat is roughly 7,700 calories (about 3,500 per pound). - Adaptive timeline: each week the tool recalculates TDEE at your new, lower weight, so the goal date reflects the natural slowdown that fixed-rate calculators ignore.
Why this calorie deficit calculator is different
Most calculators stop at one number. This one builds a plan you can actually follow.
A real goal date
See the calendar date you could hit your goal weight, plus a milestone table with your weight and calorie target along the way.
Safety guardrails
Calorie floors, a 25% deficit check, a 1% per week pace check and a goal BMI check flag plans that are likely to backfire.
Two proven formulas
Mifflin-St Jeor by default, or Katch-McArdle when you add body fat, for a more accurate maintenance estimate if you carry more muscle.
Pace comparison
Compare relaxed, steady, fast and max paces side by side, with the calories and goal date for each, before you commit.
Macros that protect muscle
Protein is set from your goal weight, with fat and carbs filling the rest, so your calorie target turns straight into a daily menu.
How to use the calorie deficit calculator
It takes under a minute, and results update as you type.
Pick your units
Choose metric or imperial. Values convert automatically when you switch.
Add your stats
Enter sex, age, height and current weight. These set your BMR.
Be honest on activity
Most people overestimate. If unsure, choose one level lower.
Set goal and pace
Enter a goal weight and choose how fast you want to lose it.
Follow and recheck
Eat your daily target, weigh weekly, and recalculate every 4 to 5 kg lost.
How big should your calorie deficit be?
For most adults, a daily deficit of about 500 calories (roughly 0.5 kg or 1 lb per week) is the best balance of speed and sustainability. Here is how the common options compare.
| Weekly loss | Daily deficit | Best for |
|---|---|---|
| 0.25 kg (0.5 lb) | about 275 calories | Lean people, athletes, the last few kilos |
| 0.5 kg (1 lb) | about 550 calories | Most adults, the recommended default |
| 0.75 kg (1.5 lb) | about 825 calories | Higher body weight with more to lose |
| 1 kg (2 lb) | about 1,100 calories | Short phases, ideally with medical guidance |
Benefits of planning your calorie deficit
A number on its own rarely changes behavior. A clear plan does.
Realistic expectations. Knowing the goal date up front stops the "why is this so slow" frustration that ends most diets in week three.
Less muscle loss. A moderate deficit with enough protein keeps more lean mass, so you look and feel better at the same weight.
Fewer plateaus. Rechecking your numbers as weight drops keeps the deficit real instead of letting it quietly shrink.
Easy maintenance afterwards. Your projection shows the calories you will need at your goal weight, so the switch to maintenance is smooth.
Calorie deficit FAQs
Straight answers to the questions people ask most about losing weight with a calorie deficit.
How many calories should I eat to lose weight?
Start with your maintenance calories (TDEE) and subtract a deficit. A 500 to 550 calorie daily deficit leads to roughly 0.5 kg (1 lb) of weight loss per week for most people. Enter your details above to get your personal number.
Is a 500 calorie deficit a good place to start?
Yes, for most adults. It is large enough to show steady progress and small enough to protect energy, sleep and muscle. Smaller or lighter people may need a smaller deficit so they stay above a sensible calorie floor.
How long will it take to reach my goal weight?
It depends on how much you want to lose and your pace. The calculator projects your goal date week by week and accounts for maintenance calories falling as your weight drops, so the date is more realistic than a simple division.
Why am I losing weight slower than the calculator predicts?
Common causes are water retention, underestimated portions, overestimated activity, and normal day-to-day scale swings. Track your weekly average for two to three weeks. If it is not moving, reduce intake by about 100 to 200 calories or lower your activity level.
What is the lowest daily calorie intake that is safe?
A widely used guideline is not to go below about 1,200 calories a day for women or 1,500 for men without medical supervision. This calculator never sets your target below those floors and warns you when your chosen pace would require it.
Should I eat back the calories I burn exercising?
Usually not. Your activity level already includes your typical exercise, so adding workout calories on top counts them twice. Only adjust if you do much more than usual on a given day.
How accurate is a calorie deficit calculator?
Formulas like Mifflin-St Jeor are typically within about 10% for most people. Treat the result as a smart starting point, then fine-tune based on what your weekly average weight actually does.
Can I lose fat without losing muscle in a calorie deficit?
Mostly, yes. Keep the deficit moderate, eat enough protein (the tool suggests about 1.8 g per kg of goal weight), and do strength training two to three times a week.
Start losing weight with a plan that fits you
A calorie deficit works best when it is personal, moderate and consistent. Get your daily calorie target, goal date and macros now, then recheck every few kilos to stay on track.
Calculate my calorie deficitThis calorie deficit calculator provides general estimates for healthy adults and is not medical advice. If you are pregnant, breastfeeding, under 18, managing a medical condition or have a history of disordered eating, talk to a doctor or registered dietitian before changing your diet.