Nine small tools for the sums that trip people up — at the shelf and in the kitchen. Nothing here is advice: it is chemistry, division, and one decay curve. You supply the targets; these only do the arithmetic.
Start here. This and the protein target below ↓ are the two numbers the macro split divides up, and both fill it in for you. This estimates maintenance calories from your stats using the Mifflin–St Jeor equation, then adjusts up or down for your goal — including gaining mass, which is otherwise easy to find a calculator for the wrong direction of.
Scaled to bodyweight, because that is what the research scales to. Note the direction: you need more protein while cutting, not less — in a deficit, protein is what stops the weight you lose coming partly out of muscle. Linked to the calorie tool above: pick a goal in either place and both follow, your saved stats fill the weight, and the result flows into the macro split.
You decide the calorie total — this only does the division. Protein and carbohydrate are 4 kcal per gram, fat is 9, which is the whole reason a "low fat" swap changes the numbers so much.
Build a plate from the food library and see the post-meal glucose rise its composition predicts — and how much the fibre, protein and fat on the same plate flatten it against the same carbs taken as straight glucose. A population-average estimate from the macros, not a forecast for you personally.
Nutrient tables describe the food as listed — usually raw. The pan then takes its share, and it takes very different shares by method: vitamin C and the B vitamins leach into boiling water, minerals mostly stay unless the water is discarded, and fat-soluble vitamins largely survive heat. Pick a food and a method to see the label adjusted by standard USDA retention factors.
The same vitamin D product is labelled "1000 IU" in the US and "25 mcg" in the UK. Vitamin E is worse: the natural and synthetic forms convert at different rates, so equal IU is not equal potency.
"325 mg ferrous sulfate" is 65 mg of actual iron. Mineral supplements are often labelled by the weight of the whole salt, so the big number on the front can be five times the amount of mineral you are getting.
We deliberately don't publish prices — they change and they vary by country. You have the price in front of you, so put it in. The point is the effective dose: a "1000 mg fish oil" capsule often contains 300 mg of the EPA and DHA you are actually buying.
Half-life is how long your body takes to clear half of a dose. Caffeine's is around five and a half hours, which is why an afternoon coffee is still measurably present at bedtime.
A simple proxy for where you carry weight, which research links to health risk more strongly than total bodyweight alone — fat carried around the waist tracks more closely with heart disease and type 2 diabetes risk than fat carried on the hips or thighs.
One combined check instead of running the others separately and doing the arithmetic yourself: type in what your actual label says, and this holds it against the reference intake and upper-limit bands in one pass.