Lose Weight Calculator: How to Work Out Your Calorie Target

At its core, a weight-loss calculator combines two things: an estimate of how many calories your body burns each day (your Total Daily Energy Expenditure, or TDEE), and a target deficit below that figure. A deficit of roughly 500 calories per day is commonly cited as producing gradual, sustainable loss — though the right figure varies considerably depending on your starting weight, height, age, sex, and how active you are.

Maintenance calories first

Before setting a deficit, you need a baseline. A calorie calculator and tracker will typically ask for your height, weight, age, and a rough activity level, then use a formula (often Mifflin-St Jeor or Harris-Benedict) to estimate your maintenance calories — the amount that keeps your weight stable. From there, subtracting a sensible deficit gives you your loss target.

Why GLP-1 users find these numbers shift

People taking Mounjaro or Wegovy commonly report significantly reduced appetite, which means many naturally eat far below their previous intake without much effort. This is worth tracking carefully: eating too little for too long can affect muscle mass, energy levels, and nutritional adequacy. General guidance suggests staying above around 1,200 kcal for women and 1,500 kcal for men as an informal floor, though your prescriber or doctor is the right person to advise on what is appropriate for you personally.

Steps and activity matter too

Some calculators let you factor in daily step count or activity minutes to refine your TDEE. While no published formula translates steps to weight loss with precision, adding movement generally widens the deficit and supports overall health. If you are curious about how activity feeds into the numbers, a weight reduction calculator can help you model different scenarios.

Related tools worth using alongside this one

A standalone lose weight calculator is most powerful when paired with daily tracking. You might also find it useful to explore a calorie intake guide for weight loss for context on how calorie targets translate into real food choices, or a timeline calculator to estimate how long it might realistically take to reach a goal at a given deficit. For day-to-day calorie counting, a general-purpose calorie counter makes logging each meal straightforward.

Once you have your calorie target, the challenge is actually hitting it consistently — and that is where GLP Trackr's food logging becomes genuinely useful. Rather than manually adding up meals, you can point your phone camera at a plate and let the AI photo scan estimate the calories and macros instantly. For packaged foods, a barcode scan fills in the details in seconds.

Beyond calories, the app lets you set a daily protein target — important on a GLP-1 journey when appetite is reduced and preserving muscle matters. You will also see your food, weight, and energy data together in one place, so patterns become visible: for instance, whether days with higher protein correlate with better energy or more consistent weight movement.

When you have a clear picture of your intake relative to your calculated target, conversations with your prescriber or doctor become much more productive. GLP Trackr includes a doctor report feature that pulls your logged data into a summary you can bring to an appointment.

A note on targets: the numbers a calculator produces are estimates based on population averages. Individual responses vary, and any decision about your specific calorie or nutrition targets is best made in discussion with your healthcare professional — especially if you have underlying health conditions or are on other medications.

Ready to put your calculated target to work? Download GLP Trackr on the App Store or Google Play and start a free 7-day trial — log your meals, set your calorie and protein goals, and watch how the data adds up across your week.