Combines TDEE calculation and
Combines TDEE calculation and deficit math in one place — no juggling separate calculators.
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Calorie Deficit Calculator
Calculate the daily calorie target and timeline for safe, sustainable weight loss based on your TDEE and goal rate.
About Calorie Deficit Calculator
The Calorie Deficit Calculator turns a target weight-loss rate into a concrete daily calorie target and a weekly deficit. It accepts TDEE directly or computes it from age, sex, height, weight, and activity using Mifflin-St Jeor. The math anchors on the standard energy balance: ~7,700 kcal/kg (3,500 kcal/lb) of body mass change. Safety guardrails warn when your loss rate exceeds ~1 kg/week (2 lb/week), which evidence-based guidelines flag as unsustainable, and when your daily intake drops below conventional floors (~1,500 kcal men, ~1,200 kcal women). Sustainable fat loss is 0.5-1% of body weight per week, paired with adequate protein and resistance training to preserve lean mass. This calculator is for educational purposes only and is not a substitute for professional medical advice. Always consult a qualified healthcare provider before making decisions about your health.
Why use Calorie Deficit Calculator
Built-in safety guardrails warn
Built-in safety guardrails warn when targets exceed sustainable rates or drop below safe floors.
Mifflin-St Jeor BMR plus
Mifflin-St Jeor BMR plus standard activity multipliers — the most accurate widely-used equation.
Project total timeline in
Project total timeline in weeks when total weight to lose is provided.
Imperial or metric units throughout
Imperial or metric units throughout, with rate auto-switching.
Privacy-first
your weight, height, age, and goals never leave your browser.
How to use Calorie Deficit Calculator
- Choose 'Auto-compute TDEE' to enter age, sex, weight, height, and activity, OR pick 'I know my TDEE' if you already have a number.
- Pick your unit system (kg/cm or lb/in) — the rate field switches automatically.
- Enter a target loss rate per week (typical recommended range: 0.25-1 kg or 0.5-2 lb).
- Optionally enter the total amount you want to lose to see a projected timeline in weeks.
- Review the daily calorie target, weekly deficit, and any safety warnings before starting.
- Track adherence weekly and adjust if real-world weight loss is faster or slower than projected.
When to use Calorie Deficit Calculator
- Starting a fat-loss phase and needing a concrete daily calorie target.
- Adjusting your deficit when weight loss stalls or accelerates unexpectedly.
- Setting realistic expectations for how long a goal will take.
- Avoiding aggressive deficits that lead to muscle loss or disordered eating patterns.
- Coaching others through goal-setting with evidence-based guardrails.
- Preparing for a competition, photoshoot, or weight class with a structured timeline.
Examples
82 kg male, TDEE 2,600, target 0.5 kg/week
Input: TDEE 2600 kcal, Loss rate 0.5 kg/week
Output: Daily deficit ≈ 550 kcal; target intake ≈ 2,050 kcal; weekly deficit 3,850 kcal
65 kg female, TDEE 1,950, target 0.75 kg/week
Input: TDEE 1950 kcal, Loss rate 0.75 kg/week
Output: Daily deficit ≈ 825 kcal; target intake ≈ 1,125 kcal — WARNING: below 1,200 kcal safe floor
100 kg male, lose 15 kg, target 0.8 kg/week
Input: TDEE 2900 kcal, Loss rate 0.8 kg/week, Total 15 kg
Output: Daily deficit ≈ 880 kcal; target intake ≈ 2,020 kcal; projected ≈ 19 weeks
Tips
- Aim for 0.5-1% of body weight per week — fast enough to see progress, slow enough to keep muscle.
- Eat 1.6-2.2 g of protein per kg of body weight during a deficit to minimize muscle loss.
- Re-check TDEE every 4-6 weeks during a long cut — metabolic adaptation reduces it as you lose mass.
- Take one maintenance week at TDEE every 8-12 weeks to reset hormones and adherence.
- Track 7-day rolling average weight rather than daily numbers to filter out water-weight noise.
Frequently Asked Questions
How accurate is this calculator?▾
BMR via Mifflin-St Jeor is typically within ±10% of measured BMR for most adults. The 7,700 kcal/kg conversion is a population average; individual response varies by 10-20% due to NEAT, water shifts, and gut adaptation.
Should I rely on this without a doctor?▾
For routine fat-loss goals in healthy adults, yes. Consult a qualified clinician or registered dietitian if you have diabetes, eating-disorder history, are pregnant, or are managing a chronic illness.
Are my measurements stored anywhere?▾
No. All calculations run locally in your browser. Weight, height, age, sex, activity level, and goal are never sent to any server.
Why does the tool warn me at 2 lb/week?▾
Sustained weight loss above ~1% of body weight per week (roughly 1 kg/2 lb for an 80-100 kg adult) is associated with greater muscle loss, hunger hormone disruption, and rebound regain. Research supports 0.5-1% per week as the sustainable upper bound.
What is the minimum safe daily calorie intake?▾
Conventional safety floors are 1,500 kcal for men and 1,200 kcal for women. Going below requires medical supervision; very-low-calorie diets (VLCDs) are clinical interventions, not self-directed plans.
Why is real-world weight loss slower than the prediction?▾
Metabolic adaptation can reduce TDEE by 100-300 kcal/day during a long cut, and NEAT declines automatically. Recompute TDEE every 4-6 weeks, or simply observe actual loss and adjust intake.
Can I lose only fat (no muscle) in a deficit?▾
Pure fat loss is impossible at meaningful deficits, but you can minimize muscle loss with high protein intake (1.6-2.2 g/kg), resistance training 3-4×/week, and modest deficit sizes (0.5%/wk).
What about cardio versus calorie tracking?▾
Both work — calorie-out via cardio is interchangeable with calorie-in reduction. In practice, food tracking is more reliable than treadmill-estimated burns, which overstate by 20-40%.
Explore the category
Glossary
- Caloric deficit
- A daily intake that is lower than total daily energy expenditure (TDEE), forcing the body to draw on stored energy (mostly fat) for the difference.
- TDEE
- Total Daily Energy Expenditure — the number of calories you burn in a 24-hour period across BMR, food digestion, NEAT, and exercise.
- BMR
- Basal Metabolic Rate — the calories your body burns at complete rest to keep organs running. Typically 60-75% of TDEE.
- Metabolic adaptation
- Reduction in TDEE during prolonged caloric deficit beyond what mass loss alone predicts; driven by hormone shifts and reduced NEAT. Roughly 100-300 kcal/day for most cutters.
- NEAT
- Non-Exercise Activity Thermogenesis — calories burned through fidgeting, posture, and unstructured daily movement; declines automatically during a deficit.
- Refeed / diet break
- Planned periods at maintenance calories during a long cut to reduce adaptation and improve adherence; typically 1-2 weeks every 8-12 weeks of dieting.