“How many calories should I eat?” is one of the most-searched health questions online — and the honest answer is that it depends on your body, how active you are, and what you want your weight to do. The good news: you can get a solid, personalised number in about a minute. This guide explains the three things that set your calorie needs, then points you to a calculator that does the math.
The short answer
Most adults need somewhere between 1,600 and 3,000 calories a day to maintain their weight. Women tend to fall in the lower half of that range and men in the upper half, but the spread is wide because it depends on size, age, and activity. To skip the estimating, enter your details in the Calorie Calculator and you'll get a target for losing, maintaining, or gaining weight.
Step 1: Your BMR (calories at rest)
Your Basal Metabolic Rate is the energy your body burns just keeping you alive — breathing, circulating blood, maintaining temperature — even if you stayed in bed all day. For most people it accounts for 60–70% of the calories they burn. The modern standard for estimating it is the Mifflin–St Jeor equation:
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age, then +5 for men or −161 for women. A 30-year-old man at 80 kg and 180 cm has a BMR of about 1,780 calories a day.
Step 2: Add activity to get your TDEE
Nobody actually stays in bed all day, so we scale BMR by an activity factor to estimate Total Daily Energy Expenditure (TDEE) — your maintenance calories. Eat at your TDEE and your weight holds steady.
Activity multipliers
- Sedentary (little or no exercise): BMR × 1.2
- Lightly active (light exercise 1–3 days a week): BMR × 1.375
- Moderately active (moderate exercise 3–5 days a week): BMR × 1.55
- Very active (hard exercise 6–7 days a week): BMR × 1.725
- Extra active (hard daily training or a physical job): BMR × 1.9
Be honest here — most people overestimate their activity. If our example man is moderately active, his TDEE is about 1,780 × 1.55 ≈ 2,759 calories a day. The TDEE Calculator works this out for you.
Step 3: Adjust for your goal
Maintenance is your baseline. From there you nudge the number up or down:
- To lose weight, eat below your TDEE. A deficit of about 500 calories a day targets roughly one pound of fat loss per week.
- To maintain, eat at your TDEE.
- To gain weight — usually muscle — eat 250–500 calories above your TDEE and train accordingly.
A pound of body fat stores about 3,500 calories, which is where the 500-a-day rule comes from (500 × 7 = 3,500). Avoid very aggressive deficits: dropping below roughly 1,500 calories a day for men or 1,200 for women makes it hard to get enough nutrients and usually backfires.
A worked example
Take that 30-year-old man — 80 kg, 180 cm, moderately active. His BMR is about 1,780 and his TDEE about 2,759. To lose roughly a pound a week he'd aim for about 2,259 calories a day; to gain, about 3,009. Plug your own numbers into the Calorie Calculator to see all three targets at once.
Calories aren't the whole story
Your calorie target sets the energy budget, but what you eat decides how you look and feel. Prioritise protein — it preserves muscle in a deficit and keeps you full — eat mostly whole foods, and don't fear the occasional treat. Pair the number with resistance training if your goal is body composition rather than just scale weight.
Calorie targets are estimates built from population averages, so treat your number as a starting point. Track your weight over two to three weeks and adjust by 100–200 calories if it isn't moving the way you want. For a quick health screen alongside this, the BMI Calculator checks whether your weight is in a healthy range for your height.