About Deficitly

Last updated 11 November 2026

Why we built it

Most calorie calculators ask you to pick an activity level, "lightly active" or "moderately active", and multiply. Few people know which one they are, and one step up the scale can add 250 calories or more a day. Deficitly starts from things you can count: your average daily steps and the workouts you actually do. Then it checks itself against your scale, because your weight trend is the most honest measure of what you burn.

What makes Deficitly different

• Real activity, not a multiplier. Your burn is built from your steps (stride worked out from your height) and your workouts, with steps inside a workout not counted twice.
• It learns your real burn. Log your weight and what you eat, and Deficitly compares the two to measure what you really burn, then blends it into your number. Many apps keep this "adaptive" estimate behind a subscription.
• Free, with no account. Every feature on this page is free. There is nothing to sign up for and no email to give.
• Private by design. Your body details, weigh-ins and food log are saved in your browser, not on our server; if you turn on sync, our server keeps only an encrypted copy it can't read. No ads, analytics or tracking scripts (privacy policy).
• Honest numbers. Every result comes with a ±10% range, and the formulas, constants and studies behind them are published on How Deficitly calculates.
• Safe by default. Goals default to losing 0.5% of your body weight a week (never more than 1%) and never go below 1,200 calories a day for women or 1,500 for men.
• Works offline. Install it on your phone's home screen and it opens like an app, even without a connection. Once your details are in the calculator, the installed app opens on your food log. On Android, long-press the icon for Add food and Log weight.
• Sync between your devices. Use Deficitly on your phone and your computer with the same data: turn on sync in Settings and link the other device with a QR code, a link or a 6-digit code. Your weigh-ins, food log, recipes, meal plans and settings then stay the same on both, on their own. End-to-end encrypted, no account, free (how sync works).

The calculator

• Daily burn (TDEE) from your resting burn (Mifflin-St Jeor, or Katch-McArdle when you know your body fat), everyday movement, digestion, average steps and weekly workouts.
• Workouts from 112 activities with intensities from the 2024 Adult Compendium of Physical Activities, counted as the extra calories above resting.
• Goal planner three ways: by a pace, by a target date, or from what you eat now ("I eat 1,800 a day: how fast will I lose?"). It shows your daily target and the date you reach your goal. Gaining weight works too.
• Protein, carbs and fat for your goal, with protein scaled to a healthy weight rather than your current one.
• What if… sliders: see how more steps or an extra session a week changes your burn and your goal date.
• Share image of your result, drawn on your device.
• kg, lb and stones; cm or feet and inches; km/h or mph. Light and dark theme.

The food log

• Search over 3 million products by name, from our own copy of the Open Food Facts database, plus over 12,000 basic foods, dishes and fast-food items from USDA data with their common portions.
• Barcode scanner that reads the code with your camera on the device; the picture is never uploaded. It works on iPhone too.
• Log in grams, ounces, servings or portions; drinks in ml or fl oz.
• Same as yesterday: an empty meal offers yesterday's foods for that meal, so a repeated breakfast or lunch takes one tap.
• Fast logging: quick add of calories, favourites, recent foods, and your own foods.
• Saved meals: save a meal once and add all of it in one tap, adjusting amounts as you go. Copy or move a meal to another day.
• Recipes: enter the ingredients once and Deficitly works out the calories and macros per serving; log it by servings or by grams, with the cooked weight if you weigh the pot.
• Daily targets for calories, protein, carbs and fat, and your daily deficit: what you burned minus what you ate.
• Extra activity: log the steps and workouts beyond your usual day, like a long weekend walk or an extra swim, and choose to bank them for a bigger deficit or eat them back with a higher target that day.
• Meal planner: plan your meals for the days ahead in the Plan tab, with each day's planned calories and protein against your targets and the week's planned deficit. Copy a planned day to other days. Planned food does not count until you tap Ate it on Food, or change the amount first. Your recipes and saved meals have their own list in the Plan tab: open, edit or delete them, or plan a serving of a recipe, or a whole saved meal, on any day.
• Shopping list: from your planned food, for this week, next week or dates you pick. Recipes are split into their ingredients, cooked foods that have a known raw counterpart are listed by their raw weight, and the same food is added up. Tick things off as you shop, and share the list or copy it as plain text.

Progress

• Weigh-ins and trend weight: a smoothed trend line that looks past daily water swings, with your weekly rate of loss or gain.
• Your real burn, measured from your weight trend and logged calories, and blended into the calculator's estimate as the data builds up.
• Weekly deficit: the calories you saved each week against your burn, over the days you logged, with roughly how much body weight that equals, and the 4 weeks before for comparison. A day you did not log is left out, not counted as zero. You can share your week as an image.
• Backups and exports: export one backup file to keep your data safe or move it to another device, and download your weigh-ins and daily calories as CSV for a spreadsheet.

Calculators and guides

Besides the main calculator, Deficitly has calculators for single questions:

• Calorie deficit calculator: How much to eat to lose weight: gentle to fast paces side by side, with dates.
• Macro calculator: Calories plus grams of protein, carbs and fat for losing fat, maintaining or building muscle.
• Calories burned calculator: Any of 112 activities, for your weight and time.
• Maintenance calorie calculator: Calories to maintain your weight, from your steps and exercise. Most women need 1,600–2,200, most men 2,100–2,800.
• Body fat calculator: Your body fat percentage from a tape measure (or calipers), four methods compared, with healthy ranges for your age.
• Weight loss percentage calculator: How much of your body weight you have lost, your weekly pace, and a fair ranking for weight-loss challenges.
• Protein calculator: Grams of protein a day for your goal, per meal, and in real food, scaled to a healthy weight.
• BMR calculator: Your basal metabolic rate by three formulas side by side, and what to do with it.
• Walking calorie calculator: Calories burned walking by time, distance or steps, with pace and incline.
• Weight gain calculator: Calories to gain weight: maintenance plus a slow, lean-bulk or faster surplus, with a goal date and protein.

And 73 short guides that answer one question each, from how many calories to eat to why your weight jumps around, all in All questions. Each opens with a direct answer, uses the same math as the app, and cites its studies.

Who runs Deficitly

Deficitly is an independent project run by Andris Zarins in Latvia, on a server we run ourselves. It is written in English and made for adults anywhere. Questions, bug reports and ideas are welcome through the contact form; we read every message.

Deficitly gives estimates for healthy adults, not medical advice. If you are pregnant, have a medical condition or an eating disorder, talk to a doctor before changing how you eat.