BMR and TDEE calculator
Enter your client's stats and instantly see their calorie targets for fat loss, maintenance, and muscle gain. Includes estimated macro splits you can share directly with your client.
Moderate exercise 3 to 5 days per week.
Fat loss
2,275
kcal/day · ~0.5 kg/week loss
P 180g · C 247g · F 63g
Maintenance
2,775
kcal/day · maintain weight
P 148g · C 339g · F 92g
Muscle gain
3,025
kcal/day · ~0.25 kg/week gain
P 164g · C 403g · F 84g
Calories burned at complete rest
Total daily calories including activity
Calculated with Mifflin-St Jeor · Activity: Moderately active (×1.55). Macros use 2.2/1.8/2.0 g protein per kg and 25–30% fat. Adjust after 2 weeks.
Everything a coach needs to know about BMR and TDEE
The numbers this calculator gives you are only useful if you know what to do with them. Here is a plain-English guide to the science, the formulas, and how to apply the results with real clients.
The basics
What is BMR and why should you care?
BMR (basal metabolic rate) is the number of calories your client's body burns to stay alive while completely at rest. No movement, no digestion, no stress — just the energy needed to keep the heart beating, lungs breathing, and cells repairing.
Think of it as the floor. It is the minimum your client must eat to sustain basic organ function. You should never build a diet plan that consistently drops calories below this number.
BMR — the floor
Calories burned at complete rest. If your client lay still in bed all day, this is what they'd burn. About 60–70% of total daily energy in sedentary people.
TDEE — the real number
Total daily energy expenditure. BMR plus everything else: walking, digesting food, exercising, and general daily movement. This is the number you build their diet around.
TDEE is split into four components behind the scenes:
- BMR — roughly 60% of TDEE for most people
- TEF (thermic effect of food) — about 10%. Digesting food burns calories too.
- EAT (exercise activity thermogenesis) — planned workouts, varies widely.
- NEAT (non-exercise activity thermogenesis) — all unconscious movement: fidgeting, walking to the kitchen, standing. Highly underestimated.
Using the results
How to turn TDEE into a goal-based calorie target
TDEE is maintenance. To change body composition, you create a calorie surplus or deficit around it. Here is the framework this calculator uses, built on research that prioritises sustainable change over fast results.
Fat loss: TDEE minus 500 kcal
A 500 kcal daily deficit creates a weekly shortfall of roughly 3,500 kcal, which corresponds to approximately 0.5 kg of fat per week. This rate is aggressive enough to show visible progress but conservative enough to preserve muscle and keep energy levels manageable.
If your client is under 60 kg or very lean, consider a smaller deficit of 200–300 kcal instead.
Maintenance: TDEE
Eating at TDEE keeps bodyweight stable over time. Use this phase between cuts and bulks to improve performance, consolidate progress, and reset diet fatigue. It is also the right starting point for a new client you want to assess over 2–3 weeks before deciding direction.
Muscle gain: TDEE plus 250 kcal
A modest 250 kcal surplus supports muscle protein synthesis without excessive fat gain. At beginner to intermediate level, this is enough to gain roughly 0.25 kg per week. More advanced clients gain muscle more slowly and should use an even smaller surplus (100–150 kcal).
These are starting points, not prescriptions.
Adjust targets every 2–3 weeks based on real results. If a client on the fat loss target is not losing weight after two weeks, reduce by another 100–150 kcal. If someone on the muscle gain target is gaining faster than 0.3 kg/week, pull back by 100 kcal.
The formulas
Standard vs Precise: which formula should you use?
This calculator uses two scientifically validated equations. The right choice depends on what data you have available.
Standard: Mifflin-St Jeor (1990)
The most widely validated formula for the general population. Published by Mifflin et al. in the American Journal of Clinical Nutrition, it consistently outperforms older equations like Harris-Benedict in accuracy testing. Uses age, sex, height, and weight to predict BMR.
Men:
(10 × weight kg) + (6.25 × height cm) − (5 × age) + 5
Women:
(10 × weight kg) + (6.25 × height cm) − (5 × age) − 161
Use this for almost every client. The margin of error is around ±10% for the general population, which is accurate enough to build a starting calorie target around.
Precise: Katch-McArdle (1975)
Instead of using total bodyweight, this formula calculates from lean body mass (LBM), which is bodyweight minus fat mass. That makes it more accurate for muscular clients, very lean athletes, and anyone whose body composition differs significantly from the average.
Lean body mass (LBM):
LBM = weight kg × (1 − body fat % ÷ 100)
BMR from LBM:
370 + (21.6 × LBM kg)
Use this when you have a reliable body fat reading from DEXA, a calibrated body fat scale, or skinfold calipers. A good reading makes this formula noticeably more accurate for leaner or more muscular clients. A rough guess will make it less accurate than the Standard formula, so use it only when you have real data.
Common mistake
Most clients overestimate their activity level
This is the single biggest source of error in TDEE calculations. A client who trains 5 days a week but sits at a desk for 8 hours a day and drives everywhere is not "very active". They are probably "lightly active" to "moderately active" at best.
Sedentary
Desk job, no planned exercise, drives everywhere
More common than people admit. Start new clients here if unsure.
Lightly active
1–3 workouts per week but otherwise sedentary
The most common starting point for the average adult client.
Moderately active
3–5 workouts per week with some daily walking
Fits clients who train consistently and stay somewhat active outside sessions.
Very active
6–7 intense sessions per week or a physical job
Reserved for committed athletes or people on their feet all day.
Extra active
Professional athletes, daily doubles, manual laborers
Rare. If you are unsure, do not use this level.
When in doubt, pick one level lower than you think. It is much easier to explain to a client why they are losing weight faster than expected than to explain why the plan is not working.
FAQ
Frequently asked questions
How often should I recalculate TDEE for a client?
Every 4–6 weeks, or whenever their bodyweight changes by more than 3–4 kg. As clients lose mass, their BMR decreases and their TDEE drops with it. Failing to update the target is one of the most common reasons fat loss stalls after the first few weeks.
My client is eating at the deficit but not losing weight. What now?
First, check tracking accuracy — underreporting is far more common than metabolic adaptation in the early weeks. Ask the client to log every bite including oils, sauces, and drinks for 3 days. If tracking is solid, reduce calories by 100–150 kcal or add a 20-minute walk on non-training days before dropping further.
Can I use this calculator with female clients?
Yes. Mifflin-St Jeor was validated across both sexes and has separate constants for men and women. The Katch-McArdle formula is sex-neutral since it works from lean body mass, not from hormonal or physiological differences between sexes.
How accurate is this calculator?
Predictive equations have an inherent margin of error of 10–15% because individual metabolic rates vary. Treat the output as a starting estimate, then adjust based on 2–3 weeks of real-world data. The trend matters more than the absolute number.
Should I use this during a client's first consultation?
Yes — it is one of the best uses. Running the numbers together on screen makes the calorie conversation concrete, shows the client you are science-led, and gives you a defensible starting point. Just be clear it is an estimate, not a lab measurement.
How do the macro splits work?
The calculator sets protein at 2.2 g per kg for fat loss, 1.8 g per kg for maintenance, and 2.0 g per kg for muscle gain. Fat is set at 25–30% of total calories. Carbs fill the remaining calories. If your client has dietary restrictions or a strong preference, adjust carbs and fat while keeping protein consistent.
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Start for freeThis calculator uses established equations from peer-reviewed research. It is intended as a coaching aid, not a clinical tool. Individual results depend on genetics, medical history, hormonal status, and other factors beyond what any equation accounts for.