The biggest number in your day is the one you make lying still.
Your daily figure is three numbers of very different size, stacked. The biggest is your body idling, and no amount of training moves it. Here they are, drawn to scale.
Where a day’s burn actually comes from
Three terms, one bar, drawn in proportion. The first is what you would burn lying still all day. The second is everything else you do. The third is the gym.
Six sessions, or one job
Every cell below is the same person — you — with a different job and a different number of sessions. Step one column right and three rows up, and the number does not change.
| Maintenance, kcal/day | |||
|---|---|---|---|
| Sessions a week | Desk | On my feet | Physical work |
Moving it around the week changes nothing
Training days get more, rest days get less — that is what every plan on this site does, including ours. Here is the week it produces, with your daily target drawn across it.
What each birthday takes off it
One of the four terms in the resting-rate formula is your age, at −5 kcal a year, and it is the only input on this page that moves without you touching anything. Here is the whole of that term, holding everything else exactly where you have it.
Everything above, in one currency
The resting rate is four terms added together, so every input carries a fixed price and any one of them can be written in any other. The multiplier cancels out of these swaps — a kilogram is worth the same two years whichever job you ticked.
| One unit of | = kg | = years | = cm |
|---|
The box you have not looked at
Three of the boxes at the top of this page can be moved. Here is how far each one travels, end to end, and where you have it parked.
How each figure is worked out
- Resting rate. Mifflin-St Jeor: 10 × kg + 6.25 × cm − 5 × age, then +5 for men and −161 for women. It is an estimate from a population, not a measurement of you; two people who match on all four inputs can genuinely differ by a few hundred kcal a day.
- The rest of your day is a multiplier on that resting rate: 1.15 at a desk, 1.30 on your feet, 1.45 in physical work. These are the conventional activity factors, and they are rules of thumb — the published ranges around them overlap.
- Training adds 0.05 to that multiplier per session a week. Because the multiplier applies to all seven days, one weekly session works out to 0.05 × resting rate × 7 — shown below the bar, so you can check it against what a session actually costs.
- The diagonal is not a coincidence and not a claim about the world. It falls out of the two constants above: one step of job is 0.15, one session is 0.05, so a step of job is three sessions and desk → physical is six. Different activity factors would move it; that they are three-to-one is a convention, and the page prints it rather than hiding it inside a total.
- The week gives training days target × (1 + 0.10 × rest days/7) and rest days target × (1 − 0.10 × training days/7). Multiply each by how many days of that kind there are and the swing cancels exactly, which is why the total does not move. Each day is then rounded to the nearest 10 for the table, and the total is the sum of the rounded numbers rather than the exact one — so what is printed adds up to what is printed.
- The age line is that same resting-rate formula with only the age term moved, times your multiplier — so it is a straight line because the formula is, not because bodies are. The vertical axis starts at zero: cropped to the range the line actually occupies, a slow drift would be drawn as a cliff.
- The price list is measured off the formula rather than typed into the page. Each row is what the resting rate does when one input moves by a single unit and the other three hold still, which is why it cannot drift out of step with the arithmetic in the first item — it is produced by it. Every cell is a ratio of two of those slopes, so the multiplier cancels and none of them move when you touch the chips. The 166 kcal behind the last row is the distance between +5 and −161.
- The three bars are the full travel of the three boxes at the top of the page: 0.30 × resting rate for the job box, 0.15 × resting rate for the sessions box (three steps of 0.05), and 0.32 × maintenance for the goal box (+12% down to −20%). The dot on each bar marks where you have that box set.
- None of this is measured. No body-fat percentage, no metabolic test, no record of what you ate. Treat every figure as a starting estimate to correct against the scale, and take medical questions — including whether a deficit is a good idea for you at all — to someone who can examine you.
This is general information, not medical or dietary advice. Every figure on this page comes from a population formula, and conditions such as thyroid disease, diabetes, eating disorders, pregnancy and a long list of medications change what is appropriate. If any of those apply, the numbers that count are the ones your doctor gives you.