How many calories do you need per day?

Short answer

Your calorie needs depend on body size, activity and your goal, among other things. A calculator gives an estimate, not a measurement of your exact daily expenditure.

Maintenance is not a fixed number for ever

You use energy for bodily functions and movement. Changes in weight and activity also change your needs. That is why simple rules do not work equally well for everyone. In its Body Weight Planner, the NIDDK uses a dynamic model that takes account of changes during weight loss. ^[1]

Use an estimate as a starting point

A practical approach is to first get a rough picture of your current food intake and activity. Then look at the trend in weight, how you function and your training, not just at a single day. Adjust a plan with a dietitian if needed; do not try to 'eat back' every calorie from your sports watch exactly.

A calculation also does not tell you whether your diet contains enough fibre, vitamins or other nutrients. Composition and feasibility remain important. ^[2]

Who is a standard calculator not meant for?

A general adult weight-loss calculator is not suitable as personal advice for children, pregnancy or breastfeeding. The NIDDK excludes these groups from its planner. ^[1] With eating problems or medical considerations, individual advice is also wiser than an automatically lower number.