Calorie Deficit Calculator — Maintenance, Safe Deficit & Time to Goal
Estimate your daily calories for weight loss, see your TDEE and BMR, and get a realistic timeline and macro breakdown for reaching your goal weight.
Enter your details
Example: 5 ft 9 in
We keep your chosen deficit and weekly target consistent. If they conflict, the calculator prioritizes a safe deficit.
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Based on 7,700 kcal per kg of fat and standard activity multipliers.
Suggested daily macros
Calories
— kcal
Protein
— g
≈ — g/kgCarbs
— g
Fat
— g
Macros are one possible starting point. Adjust for your preferences, medical conditions, and guidance from a professional.
How to use this calculator
Enter your age, sex, height, current and goal weights, activity level, and the weekly trend you are targeting. Select a macro split if you would like nutrition guidance. Use the sliders to tune your daily deficit and weekly change, then press Calculate.
The calculator runs the Mifflin–St Jeor equation, multiplies by your activity factor, and then applies your deficit or surplus to determine daily targets, macros, and a projection table.
- BMR and TDEE values adjust to your inputs and activity level.
- The deficit slider feeds into a weekly change estimate based on 7,700 kcal per kilogram of fat.
- Suggested macros break the target calories into protein, carbs, and fats using your chosen preset.
How this calorie deficit calculator works
This tool is designed to be transparent. It shows you:
- Your BMR using the Mifflin–St Jeor equation.
- Your TDEE based on an activity multiplier.
- A customizable calorie deficit and estimated weekly weight change.
- A realistic time frame to reach your goal weight.
- A suggested macro split (protein, carbs, fat).
BMR formula (Mifflin–St Jeor)
For men:
\(\text{BMR} = 10 \times \text{weight}_{kg} + 6.25 \times \text{height}_{cm} - 5 \times \text{age} + 5\)
For women:
\(\text{BMR} = 10 \times \text{weight}_{kg} + 6.25 \times \text{height}_{cm} - 5 \times \text{age} - 161\)
BMR is the energy your body uses at rest for vital functions.
From BMR to TDEE
We multiply BMR by an activity factor to estimate total daily energy expenditure:
- Sedentary: \(\times 1.2\)
- Lightly active: \(\times 1.375\)
- Moderately active: \(\times 1.55\)
- Very active: \(\times 1.725\)
- Extra active: \(\times 1.9\)
This gives an approximate number of calories you burn per day.
Calorie deficit and weekly weight loss
A deficit means eating fewer calories than your TDEE. The calculator uses the approximation:
\(1 \text{ kg fat} \approx 7{,}700 \text{ kcal}\)
\(1 \text{ lb fat} \approx 3{,}500 \text{ kcal}\)
Therefore a daily deficit \(D\) leads to:
\(\text{Weekly change} \approx \dfrac{7 \times D}{7{,}700} \text{ kg/week}\)
Macro calculation
After setting your calorie target, we apply the macro preset. For the balanced split (30/40/30):
\(\text{Protein grams} = \dfrac{0.30 \times \text{Calories}}{4}\)
\(\text{Carb grams} = \dfrac{0.40 \times \text{Calories}}{4}\)
\(\text{Fat grams} = \dfrac{0.30 \times \text{Calories}}{9}\)
We also show protein per kilogram of body weight so you can stay in a muscle-friendly range.
What is a healthy calorie deficit?
For most adults, sustainable deficits look like:
- 300–500 kcal/day for slow, steady loss.
- 500–700 kcal/day for moderate loss.
Larger deficits may lead to muscle loss, fatigue, stronger cravings, or nutrient gaps. People with medical conditions, those pregnant or breastfeeding, or underweight individuals should consult a professional before reducing intake.
Tips for using your calorie deficit effectively
- Track trends, not single days. Weigh yourself multiple times per week and watch the 2–4 week average.
- Recalculate as you lose weight. Your TDEE shrinks as you drop pounds.
- Prioritize protein and resistance training. This helps preserve muscle mass.
- Sleep and stress matter. Poor sleep and high stress can slow progress.
Medical disclaimer
This calculator is educational and does not replace personalized medical or nutritional advice. Equations like Mifflin–St Jeor and the 7,700 kcal/kg rule are estimates and may not reflect your exact needs. Consult a qualified health professional before making major diet or exercise changes, especially if you have medical conditions or take medication.
Full original guide (expanded)
Clinical notes
Use consistent units (kg, cm, lb) and flag inputs outside physiological ranges. Always interpret results alongside clinical history and context.
Key entities: Calorie, Deficit, Calculator.
Inputs used by this calculator
- Age, sex, and accurate height/weight (metric or imperial).
- Goal weight, activity multiplier, and goal direction (lose/maintain/gain).
- Daily deficit slider, weekly change slider, and optional macro presets.
Consistency checks
Checks include non-negative values, plausible ranges, and rounding to 2–3 decimals internally.