TDEE calculator

How does the TDEE calculator work?

It takes two steps, the same two the Coachh app uses to suggest your daily calories.

1. Resting energy with the Mifflin-St Jeor equation, built from 498 healthy adults aged 19 to 78 whose resting energy was measured by indirect calorimetry:
   • Men: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
   • Women: 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
   • Not saying: the same with −78, halfway between the two (Coachh’s own choice, not part of the paper)
2. Times an activity factor for how many days a week you train: 1.3 for 0–1 days, 1.45 for 2–3, 1.55 for 4–5 and 1.7 for 6–7.

For a goal, Coachh then adjusts maintenance: minus 500 calories (or 20%, if that’s smaller) to lose weight, minus 250 (or 10%) to lose fat while building muscle, plus 300 (or 10%) to build muscle. It never suggests less than 1,200 calories a day, or 1,500 for men, and rounds to the nearest 50.

What does a worked example look like?

Take a 40-year-old man who is 5 ft 10 in (177.8 cm), weighs 200 lb (90.7 kg), trains 2–3 days a week and wants to lose weight:

1. Resting energy: 10 × 90.72 + 6.25 × 177.8 − 5 × 40 + 5 = 1,823 calories.
2. Maintenance: 1,823 × 1.45 = 2,644 calories a day.
3. To lose weight: 2,644 − 500 = 2,144, rounded to 2,150 calories a day.

That’s the example the calculator above starts with, and the first of the Coachh app’s own test cases, so the site and the app agree to the calorie.

How many calories do you burn a day at your weight?

Maintenance calories at age 35, by weight and training days a week, rounded to the nearest 10. Use the calculator for your own age and height.

Why does Coachh use training days instead of “sedentary” to “very active”?

Because training days are something you know for certain, and it’s what you tell the app. The factors are Coachh’s own and deliberately on the low side. The FAO/WHO/UNU report on human energy requirements classes a sedentary or light lifestyle at 1.40 to 1.69 times resting energy, an active one at 1.70 to 1.99 and a vigorous one at 2.00 to 2.40. Coachh’s 1.3 to 1.7 sits at or below the bottom of those ranges.

The trade-off: if you have a physical job or walk a lot on top of your training, your real number is probably higher than this calculator says. Your weight trend over a few weeks will tell you.

How accurate is a TDEE calculator?

It’s a starting point, not a measurement. A 2005 systematic review found Mifflin-St Jeor the most reliable of the common equations: it predicted resting energy within 10% of the measured value in more people, lean or with obesity, than any other. The same review warns of noteworthy errors for individuals, and that older adults and US ethnic minorities were underrepresented in the studies. The activity factor adds more uncertainty on top.

So eat at the estimate for two or three weeks, watch your 7-day average weight rather than single weigh-ins, and adjust in small steps if the trend isn’t doing what you want. Our guide to why the scale lies explains why daily numbers bounce.

Who shouldn’t use this calculator?

• Anyone under 18, pregnant or breastfeeding: energy needs are different, so ask your doctor or midwife.
• People with a medical condition or medication that affects weight or metabolism.
• Anyone with a history of disordered eating: a calorie number can do more harm than good, and a doctor or eating disorder specialist is the right place to start.
• Very muscular people: the equation sees weight and height, not how much of it is muscle, and Mifflin’s own paper found fat-free mass the best single predictor of resting energy.

The floors (1,200 and 1,500) aren’t arbitrary: the 2013 AHA/ACC/TOS obesity guideline describes weight-loss diets of 1,200–1,500 calories a day for women and 1,500–1,800 for men, or a 500 to 750 calorie daily deficit.

Does Coachh work this out for you?

Yes. Coachh does this for you every day: it suggests your calorie and macro targets with this same formula, from your latest weigh-in, your training days and your goal, so the target moves as your weight does. You can set your own numbers instead. Every Sunday, the weekly review links what you ate to how your 7-day weight trend moved, which is how you find out whether the estimate fits you. The honest limit: it’s still an estimate. Coachh doesn’t measure your metabolism, and meal estimates from photos are rougher than ones from a sentence or a barcode. How Coachh works has the details.