How this works
We estimate your resting energy with the Mifflin–St Jeor equation, then multiply it by an activity factor to estimate your total daily energy (often called TDEE).
For weight loss we subtract about 275 kcal a day for a gentle pace (roughly 0.25 kg a week) or 550 kcal for a steady pace (roughly 0.5 kg a week), in line with NHS advice to lose weight gradually.
We never go below 1,200 kcal for women or 1,500 kcal for men, never cut more than 25% of your maintenance energy, and never set a deficit for under-18s, during pregnancy or breastfeeding, or if your BMI is below the healthy range.
These are estimates. Real needs vary from person to person, so treat the number as a starting point and adjust based on how you feel and how your weight changes over a few weeks.
This tool gives general information, not medical advice. If you have a health condition, are pregnant, or are worried about your eating or weight, please speak to your GP or a registered dietitian.
Questions people ask
How accurate is a calorie calculator?
It gives an estimate based on averages. Mifflin–St Jeor is one of the more reliable equations for adults, but individual needs can differ by a few hundred calories. Watching your weight trend over two to four weeks is the best way to fine-tune it.
Why won’t it give me a lower target?
Very low intakes are hard to sustain, make it difficult to get enough nutrients and are not recommended without medical supervision. We cap the deficit and keep targets above 1,200 kcal (women) or 1,500 kcal (men).
Should I eat back calories from exercise?
Your activity level already includes regular exercise. If you do much more than usual on a particular day, eating a little more is reasonable.
I’m under 18 — can I use this?
You can see an estimate of your energy needs, but we don’t set weight-loss targets for under-18s because you’re still growing. Your GP can help if you have questions about your weight.