TDEE formula: how to calculate your total daily energy expenditure

What TDEE is made of

Your daily energy use has three parts. Basal metabolic rate (BMR), the energy to keep the body running at rest, is the largest share for most people, often around 60 to 70%. The thermic effect of food, the energy used to digest, is roughly 10%. The rest is activity: planned exercise plus everything else you do on your feet, from walking to fidgeting. Formulas cannot measure any of this. They estimate BMR from body size and age, then scale it up for activity.

TDEE = BMR × activity factor

Step 1: BMR with the Mifflin-St Jeor equation

The Mifflin-St Jeor equation (1990) uses weight in kilograms, height in centimeters and age in years:

• Men: BMR = 10 × weight + 6.25 × height − 5 × age + 5
• Women: BMR = 10 × weight + 6.25 × height − 5 × age − 161

The only difference is the constant at the end. In a spreadsheet one formula handles both with IF: =10*B4+6.25*B5-5*B3+IF(B2="M",5,-161). For person 1 that gives 800 + 1,125 − 175 + 5 = 1,755 kcal. For person 2, a 42-year-old woman of 65 kg and 165 cm, it gives 650 + 1,031.25 − 210 − 161 = 1,310 kcal. If you work in pounds and inches, convert first: kg = lb ÷ 2.2046, cm = inches × 2.54.

Step 2: multiply by the activity factor

The common activity multipliers are:

• 1.2 sedentary: desk job, little or no exercise
• 1.375 light: exercise one to three days a week
• 1.55 moderate: exercise three to five days a week
• 1.725 very active: hard exercise six to seven days a week
• 1.9 extra active: very hard training or a physical job

Person 1 is moderately active: 1,755 × 1.55 = 2,720 kcal. Person 2 is lightly active: 1,310 × 1.375 = 1,802 kcal. Keep the factors in a small table and look them up with VLOOKUP(level, table, 2, FALSE), so a change of level updates everything. FALSE forces an exact match, which is what you want for words. The XLOOKUP vs VLOOKUP guide covers the lookup itself.

These factors are a convention used by calculators and textbooks, not part of the 1990 study. Choosing your level is the largest source of error: most people pick one level too high. If you are unsure between two, start with the lower one.

Worked example: TDEE, calorie target and macros for two people

Yellow cells are inputs. Rows 6 to 17 are formulas. The activity table in rows 19 to 24 feeds the VLOOKUP in row 8. Both people are fictional.

Worked example: TDEE, calorie target and macros for two people

	A	B	C	Formula in B
1	Input / result	Person 1	Person 2
2	Sex (M/F)	M	F
3	Age (years)	35	42
4	Weight (kg)	80.0	65.0
5	Height (cm)	180	165
6	BMR (Mifflin-St Jeor), kcal/day	1,755	1,310	=10*B4+6.25*B5-5*B3+IF(B2="M",5,-161)
7	Activity level	Moderate	Light
8	Activity factor	1.550	1.375	=VLOOKUP(B7,$A$20:$B$24,2,FALSE)
9	TDEE, kcal/day	2,720	1,802	=B6*B8
10	Goal: change vs TDEE	-15%	-10%
11	Calorie target, kcal/day	2,312	1,621	=B9*(1+B10)
12	Protein (g per kg)	1.8	1.6
13	Protein (g)	144	104	=B4*B12
14	Fat (share of calories)	25%	30%
15	Fat (g)	64	54	=B11*B14/9
16	Carbohydrate (g)	290	180	=(B11-B13*4-B11*B14)/4
17	Check: kcal from macros	2,312	1,621	=B13*4+B15*9+B16*4
18
19	Activity level	Factor
20	Sedentary	1.200
21	Light	1.375
22	Moderate	1.550
23	Very active	1.725
24	Extra active	1.900

Educational only, not medical or nutrition advice. All formulas are population estimates. People who are pregnant, have a medical condition or want a very low calorie target should talk to a doctor or registered dietitian.

Step 3: from TDEE to a calorie target

Eating at your TDEE should keep your weight roughly stable. For a goal, set the target as a percentage of TDEE: Target = TDEE × (1 + change). Person 1 aims for a 15% deficit: 2,720 × 0.85 = 2,312 kcal. Person 2 aims for 10%: 1,802 × 0.9 = 1,621 kcal. A percentage scales with the person, unlike a fixed "minus 500 kcal", which is a much bigger cut for a small person than for a large one. Many sports nutrition sources suggest losing about 0.5 to 1% of body weight per week to protect muscle. For gaining, a surplus of 5 to 10% is a common starting point.

Step 4: split the target into macros

Protein and carbohydrate have about 4 kcal per gram, fat about 9. A common approach sets protein first per kilogram of body weight, then fat as a share of calories, and gives carbohydrate the rest:

• Protein: 80 kg × 1.8 g/kg = 144 g (576 kcal)
• Fat: 2,312 kcal × 25% ÷ 9 = 64 g
• Carbohydrate: what is left ÷ 4 = 290 g

For person 2 the same steps with 1.6 g/kg and 30% fat give 104 g of protein, 54 g of fat and 180 g of carbohydrate. Always close the loop: grams × kcal per gram, added up, must give the target again. Subtract calories, not grams, when you work out the carbohydrate.

How accurate is the TDEE formula?

In validation studies, Mifflin-St Jeor estimated resting energy within about 10% of the measured value for most healthy adults who were not obese, and missed more often in people with obesity. Add the guesswork in the activity factor and a TDEE estimate can easily be off by 200 to 300 kcal. Treat it as a starting point and calibrate it: eat a steady amount for two to three weeks, track your weight as a 7-day average, and adjust. If your average weight stays flat, the calories you ate are your real TDEE.

Other equations exist. Harris-Benedict (1919, revised 1984) is older and tends to give slightly higher numbers. Katch-McArdle, BMR = 370 + 21.6 × lean body mass in kg, uses body composition instead of total weight and suits people who know their body fat percentage, especially very lean or very muscular people.

Common mistakes

• Picking too high an activity level. Three gym sessions a week with a desk job is light to moderate, not very active. Overestimating activity is the most common reason a diet stalls.
• Wrong sex constant. +5 for men, −161 for women. Mixing them up moves the BMR by 166 kcal.
• Mixing units. The equation needs kilograms and centimeters. Pounds and inches give nonsense unless you convert first.
• Treating the result as exact. It is an estimate within roughly ±10% for most people. Adjust it with real weight data after a few weeks.
• Counting exercise twice. The activity factor already includes your workouts. Do not add the calories from a fitness tracker on top.
• Subtracting grams from calories. When carbohydrate gets the rest, subtract the protein and fat calories from the target, then divide by 4.