BodyCalThe quick answer
BMR is the energy your body burns at complete rest, just to stay alive. TDEE is everything you burn in a real day — your BMR plus all your movement, exercise, and digestion. TDEE is always the bigger number, and it's the one you actually plan your diet around.
Think of BMR as your engine idling in the driveway, and TDEE as the fuel you use over a full day of driving. You need to know the idle rate to work out the total.
What BMR really measures
Basal Metabolic Rate is the calories needed to keep your organs running, your blood circulating, and your temperature steady if you did absolutely nothing all day. It's the largest single chunk of your daily burn — usually 60 to 70% of the total — and it's driven mostly by your size, age, sex, and muscle mass.
You can't eat at your BMR to lose weight faster, tempting as it sounds. Sitting below it for long stretches makes it very hard to get enough nutrients and tends to cost you muscle.
How TDEE is built from BMR
To turn BMR into TDEE, you multiply it by an activity factor — from about 1.2 for a sedentary desk worker up to 1.9 for someone training hard every day. That multiplier captures the calories you burn moving around, exercising, and digesting food (which alone accounts for roughly 10%).
So a person with a BMR of 1,500 who is lightly active (×1.375) has a TDEE of about 2,060 calories. That 2,060 — not the 1,500 — is their maintenance number.
Which one should you use?
For managing your weight, use TDEE. Eat below it to lose, at it to maintain, above it to gain. BMR is the building block you calculate first, but it's not your calorie target. The single most common dieting mistake here is accidentally aiming for BMR instead of TDEE and eating far too little.
Work out your BMR with our BMR calculator, then take it to the TDEE calculator to get your maintenance calories — and on to the macro and calorie deficit calculators to build a full plan.