How many calories should I eat to lose weight?

Most people should aim for 300-500 calories below maintenance, which produces roughly 0.5-1 lb of loss a week. The calculator works out your maintenance first, then applies the deficit you pick, and never drops below 1,200 calories for women or 1,500 for men.

How fast can I safely lose weight?

Around 0.5-1% of body weight a week is the usual guidance. Faster is possible at higher starting weights, but the further you push it, the more of the loss comes from muscle and the harder it becomes to sustain.

Why has my weight loss stalled?

Three common reasons: your smaller body burns fewer calories than it used to, portion sizes have quietly crept up, or water retention is masking real fat loss. Recalculate your TDEE at your current weight and check a two-week average rather than a single morning.

Is 1,200 calories a day safe?

It is the conventional floor for women rather than a target, and it is hard to hit nutrient needs there. Most people lose weight perfectly well on considerably more than that - a larger deficit is not a better one if you cannot stick to it.

Do I need to exercise to lose weight?

No, diet does the heavy lifting for the deficit. Exercise matters for what you keep: resistance training during a deficit is the single most effective way to make sure the weight you lose is fat rather than muscle.

Weight Loss Calculator

Enter your details and goal weight to see the daily calorie target, the weekly rate and the realistic date you would reach it.

Enter your details and your result will appear here.

What Is Weight Loss?

This weight loss calculator turns a goal weight into three numbers you can act on: how many calories to eat each day, how fast you can expect to lose, and roughly when you would arrive.

It starts from your total daily energy expenditure - the calories your body burns across a normal day - and subtracts the deficit you choose. Everything else follows from that single subtraction.

Understanding Your Weight Loss Result

Fat loss is driven by energy balance. Eat less than you burn and your body makes up the difference from stored energy. A pound of body fat stores roughly 3,500 calories, so a 500-calorie daily deficit works out at about a pound a week.

That approximation is good enough for planning and slightly optimistic in practice. As you lose weight your body gets smaller and cheaper to run, so the same intake becomes a smaller deficit over time. Real weight loss curves flatten; the straight line the arithmetic predicts does not. Expect to recalculate every 10-15 lb.

The calculator will not take you below 1,200 calories a day for women or 1,500 for men. Below those levels it becomes difficult to meet basic nutrient needs, and adherence collapses long before the arithmetic does.

How Is Weight Loss Calculated?

Daily target = TDEE - deficit
Weekly loss (lb) = (deficit x 7) / 3500
Weeks to goal = total pounds to lose / weekly loss

TDEE comes from the Mifflin-St Jeor BMR multiplied by your activity factor.

How to use this weight loss calculator

Enter your sex, age, height, current weight and activity level, then your goal weight and the pace you want. The result shows your maintenance calories, your daily target, the expected weekly rate and an estimated date.

Be honest about activity - overstating it is the most common reason a calculated target fails to produce results. If you sit for work and train three times a week, that is lightly-to-moderately active, not very active.

What affects your rate of loss

Starting weight matters most: heavier bodies burn more and can sustain larger deficits comfortably. Protein intake and resistance training determine how much of the loss is fat rather than muscle. Sleep and stress influence appetite regulation more than most people expect.

Water weight muddies the first two weeks in both directions - a sharp initial drop is mostly glycogen and the water bound to it, not fat.

Making the number stick

Weigh yourself under the same conditions several times a week and work from the weekly average. If the average has not moved in three weeks and you are confident in your tracking, drop 100-150 calories rather than overhauling everything.

Recalculate after every 10-15 lb lost. A target that was right at your starting weight will be a smaller deficit than you think by the time you are two stone down.

Methodology

Your basal metabolic rate is calculated with the Mifflin-St Jeor equation, the most accurate of the widely used prediction formulas for the general population. That is multiplied by your activity factor to get TDEE, then your chosen deficit is subtracted, with the intake floor applied.

Timeline uses the 3,500-calorie-per-pound convention, which is a planning approximation, not a physiological constant.

Worked Example

A 34-year-old woman, 5 ft 5 in and 175 lb, lightly active, has a TDEE of roughly 2,050 calories. At a 500-calorie deficit she eats about 1,550 calories a day and loses close to a pound a week.

To reach 150 lb she needs to lose 25 lb, which the arithmetic puts at around 25 weeks. In practice, allow 28-32 weeks: metabolic adaptation, holidays and imperfect weeks are all normal, and the plans that succeed are the ones that budget for them.

Important Limitations

Predicted expenditure carries an error of roughly 5-10% for any individual, so your real maintenance may differ by a couple of hundred calories. The 3,500-calorie rule overstates long-term loss because it ignores the drop in expenditure that comes with a smaller body. Week-to-week scale readings are dominated by water, glycogen and gut contents, not fat. This tool is not appropriate during pregnancy or breastfeeding, for anyone under 18, or for people with a history of disordered eating without clinical supervision.

Frequently Asked Questions

How many calories should I eat to lose weight?: Most people should aim for 300-500 calories below maintenance, which produces roughly 0.5-1 lb of loss a week. The calculator works out your maintenance first, then applies the deficit you pick, and never drops below 1,200 calories for women or 1,500 for men.
How fast can I safely lose weight?: Around 0.5-1% of body weight a week is the usual guidance. Faster is possible at higher starting weights, but the further you push it, the more of the loss comes from muscle and the harder it becomes to sustain.
Why has my weight loss stalled?: Three common reasons: your smaller body burns fewer calories than it used to, portion sizes have quietly crept up, or water retention is masking real fat loss. Recalculate your TDEE at your current weight and check a two-week average rather than a single morning.
Is 1,200 calories a day safe?: It is the conventional floor for women rather than a target, and it is hard to hit nutrient needs there. Most people lose weight perfectly well on considerably more than that - a larger deficit is not a better one if you cannot stick to it.
Do I need to exercise to lose weight?: No, diet does the heavy lifting for the deficit. Exercise matters for what you keep: resistance training during a deficit is the single most effective way to make sure the weight you lose is fat rather than muscle.