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Maintenance Calorie Calculator

Ready to calculate
Mifflin-St Jeor BMR.
4 Activity Levels.
Macro Breakdown.
100% Free.
No Data Stored.

How it Works

01Tell Us About You

Sex, age, height, and weight — the inputs BMR needs

02Pick Activity Level

Sedentary through professional athlete — 4 levels

03Compute BMR & TDEE

Mifflin-St Jeor formula × activity factor

04See Macros

25% protein / 30% fat / 45% carbs by default

About the Maintenance Calorie Calculator

The Maintenance Calorie Calculator estimates the daily calorie intake at which your weight stays stable — your Total Daily Energy Expenditure (TDEE). TDEE is the sum of basal metabolic rate (~60–70%), thermic effect of food (~10%), and physical activity (varies widely). Knowing maintenance is the starting point for any deliberate weight goal: lose fat by eating below it, gain muscle by eating slightly above.


Enter age, sex, height, weight, and activity level. The calculator uses the Mifflin-St Jeor equation — the most validated BMR formula in modern nutrition research — multiplied by an activity factor (1.2 sedentary up to 1.9 athlete). You'll get TDEE in calories/day, plus suggested cuts for fat loss and surpluses for muscle gain.

How the Calculator Works

Enter biometrics: age, biological sex, height, current weight. These determine resting metabolic rate.
Pick activity level: sedentary (desk job, no exercise), light (1–3 sessions/week), moderate (3–5), high (6+), athlete (twice daily).
Apply Mifflin-St Jeor BMR: the most accurate population-level BMR formula.
Multiply by activity factor: BMR × 1.2–1.9 = TDEE.
Read suggested targets: −500 kcal for ~1 lb/week fat loss, +300 kcal for lean muscle gain.

The Math Behind It

BMR (Mifflin-St Jeor):


Men: 10·W + 6.25·H − 5·A + 5
Women: 10·W + 6.25·H − 5·A − 161
Where W = weight (kg), H = height (cm), A = age (years).


TDEE = BMR × Activity Factor


Activity factors: 1.2 (sedentary) · 1.375 (light) · 1.55 (moderate) · 1.725 (high) · 1.9 (athlete).

Real-World Example

Worked Example

30-year-old man, 180 cm, 80 kg, moderate activity:

StepCalculationResult
BMR10·80 + 6.25·180 − 5·30 + 51780 kcal
TDEE1780 × 1.552759 kcal/day
Fat loss targetTDEE − 5002259 kcal
Muscle gain targetTDEE + 3003059 kcal

Who Uses It

1
🥗 Fat-Loss Dieters: Set a sustainable −300 to −500 kcal deficit anchored to your real maintenance.
2
💪 Muscle Builders: Find the +200 to +400 kcal surplus that adds muscle without excess fat gain.
3
🏋️ Bodybuilders / Physique Athletes: Cycle calories around training days, anchored to maintenance.
4
🩺 Clinical Dietitians: Quick estimate for outpatient counseling.
5
🎯 Recomp Goals: Eat at maintenance and let resistance training do the body composition work.
6
📊 Tracking Newcomers: Establish a baseline before testing a new diet protocol.

Final Thoughts

Maintenance calories are not a fixed number — they shift with body weight, activity, and adaptive thermogenesis (the body's resistance to weight change). Use the calculator's number as a starting point, weigh yourself daily for 2–3 weeks, and adjust by 100–200 kcal if your trend doesn't match the goal. The ToolsACE Maintenance Calorie Calculator gives you a research-grade starting estimate.

Frequently Asked Questions

Why is my TDEE different from what my fitness watch says?
Wearables typically overestimate activity calories by 15–30% (especially for non-cardio movement). The Mifflin-St Jeor + activity factor approach is more conservative and tends to match real-world weight outcomes better.
Should I use Mifflin-St Jeor or Harris-Benedict?
Mifflin-St Jeor. The 2005 American Dietetic Association meta-analysis found it the most accurate BMR formula for non-obese adults. Harris-Benedict is older and tends to overestimate by ~5%.
How much should I cut to lose 1 lb/week?
Roughly 500 kcal/day below maintenance (3500 kcal ≈ 1 lb of fat). For aggressive cuts, 750 kcal/day = ~1.5 lb/week — but expect more muscle loss and more hunger at deeper deficits.
Why do I stop losing weight even though I'm in a deficit?
Three reasons: (1) maintenance dropped as you lost weight — recalculate, (2) NEAT (non-exercise activity) declines on diets, (3) you're underestimating intake. Recalculate every 5–10 lbs lost.
Does the calculator account for muscle mass?
Indirectly — Mifflin-St Jeor uses weight and height. For very muscular individuals, the Katch-McArdle formula (uses lean body mass) is more accurate. Most people don't need the precision.
What's a refeed day?
A planned 1–2 day return to maintenance calories during a long cut, mostly from carbs. Helps restore leptin, training performance, and adherence. Useful but not required for shorter (<8 week) cuts.
Is the activity factor for cardio or daily life?
Both, combined. A 'moderate' factor of 1.55 covers a desk job + 4 hours/week of structured exercise + normal daily walking. Don't double-count by adding cardio calories on top.
Should women use a different formula?
The Mifflin-St Jeor formula has built-in sex coefficients (men +5, women −161). It's been validated for both. Women generally need 200–400 fewer calories than men of the same weight due to lower lean mass.
Why not just count calories burned in workouts?
Because that double-counts and is also inaccurate. Activity factor multipliers are calibrated against real-world weight changes — far more reliable than gym-machine calorie estimates.
Is my data private?
Yes. All calculations happen in your browser. We don't store, log, or transmit your biometrics.

Author Spotlight

The ToolsACE Team - ToolsACE.io Team

The ToolsACE Team

Our health tools team implements the Mifflin-St Jeor basal metabolic rate equation — published in 1990 and since shown to be more accurate than the Harris-Benedict equation for the modern population — multiplied by standard activity factors (1.2 to 1.9) to estimate Total Daily Energy Expenditure (TDEE).

Mifflin-St Jeor EquationMacronutrient GuidelinesSoftware Engineering Team

Medical Disclaimer

Calorie estimates are based on population-average formulas (Mifflin-St Jeor). Individual metabolic rates vary ±10% from predictions. For medical conditions, eating disorders, or athletic performance goals, work with a registered dietitian.