Calorie Deficit Calculator

What is a safe calorie deficit?

A calorie deficit is simply eating less energy than you burn. The calculator finds your maintenance calories with the Mifflin-St Jeor equation and your activity level, then subtracts whatever deficit your goal and timeframe demand.

“Safe” has less to do with a fixed calorie number than with two boundaries:

• Your BMR is a sensible floor. Basal metabolic rate is the energy your body spends at complete rest. Eating below it for an extended stretch tends to make hunger, mood, and training quality worse well before it makes fat loss faster — so the calculator flags a target that lands at or below it.
• Weekly loss near 0.5–1% of body weight is the usual ceiling. This is why 2 lb/week reads very differently at 250 lb than at 140 lb. Beyond that pace, a growing share of what you lose comes from lean mass rather than fat.

The other half of “safe” is whether you can actually live in it. A 300-calorie deficit you hold for six months beats a 900-calorie deficit you abandon in three weeks, because the first one is still running when the second has already been undone. Resistance training and a high protein intake are what steer the loss toward fat rather than muscle — neither is optional if you care what the weight loss looks like.

Nothing here is medical advice, and individual responses to a deficit vary widely. If you’re managing a medical condition, pregnant or breastfeeding, or thinking about a very low-calorie diet, work with a clinician rather than a calculator.

Calorie deficit by goal: 0.5 lb vs 1 lb vs 2 lb per week

Every row below uses the rough 3,500 calories per pound of fat rule of thumb. It is a planning heuristic rather than a physiological constant, but it is close enough to set a starting target and adjust from there.

What each pace actually feels like to run:

• 0.5 lb / week. Barely noticeable day to day. Easiest to sustain, and the slowest to show up on the scale.
• 1 lb / week. The default for a reason. Visible progress, manageable hunger, good lean-mass retention.
• 1.5 lb / week. Real hunger. Works best as a defined block with an end date, with protein kept high.
• 2 lb / week. Defensible mainly at higher starting weights, where 2 lb is still a small share of your body weight. For many people a 1,000-calorie deficit lands under their resting needs — the calculator flags it when yours does.

Notice that the deficit is what you choose; the pace is what falls out of it. If you want to work backwards from a rate instead — say, you have a date in mind and want to know whether it’s realistic — the weight loss pace calculator runs the same math from the other end and grades the result.

Deficit calculator vs TDEE calculator: which to use

They run the same engine and answer adjacent questions, so the split is straightforward:

• Use a TDEE calculator when you want the raw number you burn. That’s the baseline everything else is measured against, and it’s the right starting point if you don’t have a goal weight yet.
• Use this calculator when you have a goal weight. It takes the TDEE, subtracts the deficit your goal and timeframe require, and hands back a daily target plus the date the math points to.
• Use the maintenance calorie calculator when the deficit is over. Knowing where to land afterwards is what keeps the weight off, and it deserves as much planning as the cut itself.

If you know you want to lose fat but haven’t settled on a target weight, the TDEE calculator for weight loss splits the difference: pick a rate rather than a goal, and see the deficit that rate implies.

Common mistakes when running a calorie deficit

• Overstating activity level.This is the single biggest source of error. The gap between sedentary and moderately active is roughly 30% of your BMR — for a 1,600-calorie BMR, that’s a ~500 calorie/day swing in the maintenance figure your whole deficit is subtracted from. Three hard sessions and four desk-and-couch days is lightly active.
• Undercounting what goes in.Cooking oil, condiments, the handful of nuts, the sips of the kid’s drink. None of it is logged, all of it counts. A 500-calorie deficit on paper is often a 200-calorie deficit in practice.
• Reading the scale daily and reacting. Water, glycogen, sodium, and the contents of your digestive tract move the scale several pounds in either direction independent of fat. Weigh often if you like, but judge only the weekly average.
• Cutting protein along with the calories. Protein is what signals your body to keep muscle in a deficit, and it does more for fullness per calorie than fat or carbs. When calories come down, protein should be the last thing to move.
• Skipping resistance training.A deficit without lifting tends to take lean mass along with the fat. It’s the difference between weighing less and looking different.
• Never leaving the deficit. A deficit is a phase, not a lifestyle. Plan the exit — the reverse dieting guide covers how to walk the calories back up.

If you’ve been honest about all six and the scale still hasn’t moved in a month, why am I not losing weight on a calorie deficit works through the less obvious explanations.

Frequently asked questions