How long will it take to lose the weight? A real timeline, with your calories

Losing 20 pounds takes about 20 weeks at a pound a week, or about 40 weeks at the gentler half a pound a week. The calculator above turns your actual numbers into a timeline and gives you the daily calories and macros that get you there.

Everything on this page uses the same formula the BryksBuilt app uses, so the target you see here is the target the app sets for you.

Where the timeline comes from

Three steps, and none of them are complicated.

Your maintenance calories. We use Mifflin St Jeor for your resting rate, then scale it by how much you actually move. That scaling is the part most calculators get vague about.

Your deficit. A pound of fat is worth roughly 3500 calories, so eating 500 a day below maintenance loses about a pound a week and 250 loses about half. Which one you get depends on how far your goal is: a small target gets the gentle deficit, a bigger one gets the faster one.

The division. Pounds to lose, divided by pounds per week. That is the whole timeline.

Why we ask for steps and not an activity level

Every other calorie calculator gives you a dropdown: sedentary, lightly active, moderately active, very active, extremely active. Almost everyone picks moderately active. Almost nobody is.

That single guess moves your maintenance number by 400 calories or more, which is the entire difference between losing weight and not. It is the least reliable input in the whole calculation and it is the one traditionally left to a guess.

So we ask for two facts instead. How many steps you take on a normal day, which your phone already knows, and how many days a week you actually train. A 12,000 step office worker who lifts four times a week and a 3,000 step office worker who lifts four times a week do not have the same maintenance, and a dropdown cannot tell them apart.

This is also why the number here matches the app. BryksBuilt has always run on steps rather than self assessment.

What the deficit actually feels like

A 500 calorie deficit is not dramatic on paper and is very noticeable in a kitchen. It is roughly one snack and one drink, or a smaller dinner, every day, forever, until you hit your number.

The two things that make it survivable are protein and volume. Protein keeps you full and protects the muscle you would otherwise lose alongside the fat, which is why the calculator gives you a protein target rather than just a calorie one. Volume means food that fills your stomach for few calories: vegetables, lean meat, potatoes, anything with water and fibre in it.

The thing that makes it fail is treating it as a sprint. A 1000 calorie deficit works for about nine days and then produces a weekend that undoes the fortnight.

Recalculate on the way

The number you get today is right for the body you have today. Twenty pounds from now, that same body burns less, so your maintenance drops and your original target quietly becomes a smaller deficit than it was.

Recalculate every 15 to 20 pounds, or whenever progress flattens for three weeks with your intake genuinely unchanged. That is normal and expected, not a sign that anything has broken.

The part a calculator cannot do

Knowing you need 2,190 calories and 200 grams of protein is a ten second problem. Hitting it four days out of five for five months is the whole job.

BryksBuilt sets these targets from your details when you onboard, logs your food against them, and builds meal plans and grocery lists that hit them. When your weight moves enough to matter, come back here, run the numbers again and update your targets in the app. It is free to download.