Free health tool
Calorie Deficit Calculator
Turn your maintenance estimate and goal weight into a practical daily calorie target and a realistic starting timeline.
Plan your calorie deficit
Start with pounds and inches, or switch to metric at any time.
Weight-loss pace
Choose the pace you want to use for this starting estimate.
Quick options cover the commonly used 0.5–2 lb/week range. You can use the slider for a wider planning range.
Enter an age from 18–100, a height from 120–230 cm, and valid current and goal weights. Your goal weight should be lower than your current weight.
Daily calorie target
0 kcal/day
Estimated maintenance: 0 kcal/dayAbout the result
What this calorie deficit calculator does
A calorie deficit is the gap between the energy you use and the energy you take in. This calculator estimates your maintenance calories from age, sex, height, current weight, and usual activity, then translates the pace you choose into a daily calorie target.
It is a planning estimate, not a prescription. Your energy needs, appetite, training, medications, sleep, and weight trend can all change what works in real life.
The calculation
How the daily target and timeline work
1. Estimate maintenance
TDEE = estimated BMR × activity factor
We use the Mifflin–St Jeor equation for BMR, then apply the activity level you select to estimate a typical day’s energy use.
2. Set a pace
Daily deficit ≈ weekly loss × 3,500 ÷ 7
The common 3,500 kcal-per-pound rule is a useful starting approximation. Actual weight loss rarely follows a perfectly straight line.
Why the result can drift: as weight decreases, your energy needs tend to decrease too. Water, glycogen, digestion, and changes in activity can move the scale independently of body-fat change. Treat the timeline as a range and reassess from your multi-week trend.
Choosing a pace
Pick a pace you can repeat
There is no universally right speed. A smaller deficit leaves more room for food and training; a larger one can shorten the estimate but may be harder to sustain. The CDC notes that people who lose weight at a gradual, steady pace—about 1 to 2 pounds per week—are more likely to keep it off than people who lose weight faster.
Gentle · 0.5 lb/week
About a 250 kcal/day starting deficit. A useful option when adherence, training performance, or a long runway matters more than speed.
Steady · 1 lb/week
About a 500 kcal/day starting deficit. This is a conventional middle ground for many adults, but it still needs to fit your health situation and actual progress.
Use the estimate
How to adjust your calorie target
- Start with a trend, not one weigh-in. Use comparable weigh-ins over several weeks; day-to-day changes are often water and food volume.
- Keep the first adjustment small. If your average trend is materially different from the chosen pace after a few weeks, adjust gradually rather than making a large swing.
- Protect the basics. Adequate protein, regular resistance training where appropriate, sleep, and food quality all matter alongside the calorie number.
- Get individual guidance when needed. Pregnancy, breastfeeding, adolescence, a history of disordered eating, illness, medications, and intensive athletic training can change what is appropriate.
Common questions
Calorie Deficit Calculator FAQ
What is a calorie deficit?
It means taking in less energy than your body uses over time. The gap can come from food intake, activity, or both. Body-weight change is influenced by more than calories alone, so the scale will not move in a perfectly predictable line.
How large should my calorie deficit be?
It depends on your starting point, health context, preferences, and ability to sustain the plan. CDC describes gradual loss of about 1 to 2 pounds per week as more likely to be maintained than faster loss. Use the slider as a planning tool and consult a qualified clinician for individualized targets.
Why does the calculator use 3,500 calories per pound?
It is a long-standing rule of thumb for translating a weekly loss pace into a daily energy gap. It is not a promise: metabolic adaptation and changing body composition mean that real timelines can be longer or shorter.
Why might my actual result differ from the estimated timeline?
The maintenance estimate may be imperfect, and your energy needs can change as your weight, activity, and routine change. Water retention, sodium, carbohydrate intake, menstrual cycles, and digestion can also temporarily mask fat loss on the scale.
Is a very low calorie target safe?
This calculator cannot assess your medical needs or nutritional adequacy. The NIDDK notes that eating below 1,200 calories a day is not advised in its Diabetes Prevention Program guidance. If your estimate is low, or you have a health condition or special situation, seek individualized professional support instead of pursuing a more aggressive pace.
References
Sources and limitations
- Mifflin MD, et al. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 1990.
- Centers for Disease Control and Prevention. Steps for Losing Weight—guidance on gradual, steady weight loss.
- CDC National Diabetes Prevention Program. Tip the Calorie Balance—the 3,500 kcal-per-pound rule of thumb and example deficits.
- National Institute of Diabetes and Digestive and Kidney Diseases. Body Weight Simulator—why simple prediction methods can overestimate loss by not modeling metabolic adaptation.
Medical disclaimer: This tool is for general education and is not medical advice. Talk with a qualified healthcare professional before making significant diet or activity changes, especially if you are pregnant or breastfeeding, under 18, managing a medical condition, taking medication, or have a history of disordered eating.
Related calculator
Want to see the maintenance estimate on its own?
Use the TDEE Calculator to compare activity levels and explore the underlying maintenance and BMR estimate.