Calorie deficit calculator
Enter your stats and activity level. We compute your daily burn, then show the calorie target for each rate of loss, from a gentle half pound a week to an aggressive two. Anything below a safe floor gets flagged.
How this calculator works
- Daily burn. We calculate your basal metabolic rate with the Mifflin-St Jeor equation, then apply your activity multiplier to get total daily energy expenditure. That maintenance number is where the math starts.
- Subtract the deficit. One pound of fat is about 3,500 calories. Dividing by seven days gives a daily deficit of 250, 500, 750, or 1,000 calories for half, one, one-and-a-half, or two pounds a week.
- Floor check. If a target drops below 1,200 calories a day for women or 1,500 for men, we flag it. Those paces are not wrong for everyone, but they belong under clinical supervision.
Picking a sustainable pace
Faster is not better. A pound to a pound and a half a week is the range most people can hold without constant hunger, and it protects more muscle than an extreme cut. The best deficit is the one you can still be running in three months, which is exactly where most diets fail and where appetite medication changes the odds.
Protect your muscle
A deficit costs muscle as well as fat unless you defend it. Two things do most of the work: enough protein and some resistance training. The protein calculator shows your daily grams for a deficit, which climbs above the maintenance number precisely because you are eating less overall.
Where GLP-1s fit
Knowing the target number is the easy part. Dieting fails on the day-to-day follow-through. GLP-1 medications like Wegovy and Zepbound cut appetite so the deficit sticks. If holding a deficit has failed you before, the next question is eligibility. The BMI-to-program calculator answers it and ranks the programs that serve your state.
Frequently asked questions
What is a calorie deficit?
A calorie deficit is eating fewer calories than you burn in a day. It is the one requirement every weight-loss method shares, whether the tool is diet, exercise, or medication. This calculator finds your daily burn, then subtracts a deficit sized to the pace you want.
How big a deficit should I aim for?
One pound of body fat is about 3,500 calories, so a 500-calorie daily deficit is roughly a pound a week, which most clinicians consider a sustainable pace. Larger deficits lose faster but are harder to hold and risk more muscle loss. The calculator flags any target that falls below a safe floor.
What is the calorie floor, and why does it matter?
A conventional safety floor is 1,200 calories a day for women and 1,500 for men. Below that, it is hard to get enough protein and micronutrients, and the plan usually backfires. If an aggressive pace pushes your target under the floor, the calculator marks it and flags that it needs a clinician's oversight.
Why am I not losing weight in a deficit?
Usually one of three things: the calorie count is off (portions and liquid calories are easy to undercount), water weight is masking fat loss on the scale, or your burn is lower than the estimate. Track for two to three weeks, weigh at the same time of day, and adjust the target before assuming the math is broken.
How do GLP-1 medications help with a deficit?
They make the deficit sustainable. GLP-1s like Wegovy and Zepbound reduce appetite and slow stomach emptying, so eating below your burn stops depending on willpower. The deficit target does not change; the difficulty of hitting it does. Enough protein and resistance training keep the loss coming from fat rather than muscle.
Other calculators
- TDEE calculator: the maintenance number this tool subtracts from.
- BMR calculator: your resting burn on its own.
- Protein calculator: the daily grams to protect muscle in a deficit.
- BMI-to-program calculator: your BMI and the programs you qualify for.
