FitDexMacro calculator
A calorie total isn't a sufficient target on its own. How much protein sits inside that same 2,000 calories determines how full you stay, how well you recover from training and how much of the weight you lose comes from muscle rather than fat, so two days showing the identical number on the tracker can end up producing entirely different outcomes. The calculation below turns calories into grams.
Your daily calorie target
- Protein168 g
- Carbs253 g
- Fat62 g
- Basal metabolic rate1,452 kcal
Capped at the safety floorYour figure fell below this value; we don't show targets under 1,200 kcal for women or 1,500 kcal for men. Intakes that low aren't something to attempt without professional supervision.
Start tracking this goalThis number comes from the very same formula the FitDex app uses. Install the app and you won't be handed a different target.
How is it calculated?
First your daily calorie target is worked out: basal rate via Mifflin-St Jeor, total expenditure via the activity multiplier, then 400 calories off or on according to your goal. Macros are split out of THAT result — change your goal and the grams change with it.
The ratio used: 30% of calories as protein, 45% as carbohydrate, 25% as fat. Grams come from 4 calories per gram for protein and carbs, 9 for fat. On a 2,251-calorie target that works out to 168 g protein, 253 g carbohydrate and 62 g fat.
Why 30% protein: for someone at 70 kilos that's about 2.4 grams per kilo — above the 1.6–2.2 g band shown to be enough for preserving muscle, so comfortably on the safe side. Protein is also the most satiating macro and the most expensive to digest; because 20–30% of its calories go on digestion, roughly 130 calories of a 168-gram protein target are handed back before they ever count (the same share is 5–10% for carbohydrate and 0–3% for fat).
Fat sitting at 25% rather than lower is deliberate. Fat is needed for hormone production and for absorbing vitamins A, D, E and K; diets that drop below 20% of total calories cause problems over the long run. The remaining 45% carbohydrate is what carries training intensity and the fuel the brain prefers.
This ratio is a starting point, not a doctrine. Below we set out when you should shift it — knowing when to leave a ratio behind is as much part of the calculation as the ratio itself.
How to read your result
Only one of the three numbers really matters: protein. With total calories and protein held fixed, how you split the rest between carbohydrate and fat doesn't meaningfully change body composition. Dropping carbs to 200 grams and raising fat works; so does the reverse. Hitting your protein, on the other hand, isn't optional.
When to shift protein: under 60 kilos, the 30% ratio can push you past 3 grams per kilo — unnecessary but harmless, and worth lowering if it sits heavily. If you lift seriously and you're in a deficit, the opposite applies: going up to 2.2 grams per kilo helps preserve muscle. In kidney disease the amount must be set by a clinician; there's no evidence that high protein harms healthy kidneys, but that doesn't reverse the exception.
Don't take fat below 20%. The first thing you notice on a low-fat plan is the loss of satiety. The second is reduced absorption of fat-soluble vitamins: leaving the oil off a salad makes part of the vitamin A and K in that salad unusable, sitting on the plate but never entering the body.
Tune carbohydrate to training intensity. For someone lifting three days a week, 45% is more than enough. If you do endurance work — long runs, cycling — that ratio is low; pushing carbs to 55% and cutting fat noticeably improves performance. If you don't train at all, dropping carbs to 35% and raising protein and fat produces an easier day in terms of fullness.
You don't have to hit the grams exactly every day. The weekly average decides more than daily precision. Being 30 grams short of protein one day changes nothing; being 40 grams short every day for a week adds up to a 280-gram shortfall across that week, and that much does leave a measurable mark on muscle retention.
Frequently asked questions
Why not 40/40/20 or some other ratio?
Because most of these ratios have no measurable advantage over each other. Once total calories and protein are matched, the effect of the carbohydrate-versus-fat split on weight loss and body composition disappears in head-to-head studies. The 30/45/25 we chose keeps protein comfortably on the safe side, keeps fat above its healthy floor and leaves carbohydrate high enough to carry a normal training week. If you're an endurance athlete, or you feel better on lower carbohydrate, shift it — you lose nothing, as long as you hit your protein and your total calories.
Will this much protein damage my kidneys?
There's no evidence of that in healthy kidneys. The idea that high protein strains the kidneys comes from the observation that restricting protein slows progression in people who ALREADY have kidney disease — a correct observation, but generalising it to healthy kidneys is a faulty inference. Long-term follow-up in athletes and people on high-protein diets shows no deterioration in kidney function. If you have diagnosed kidney disease, though, the situation is different: then the amount should be set by your doctor, not by this calculator.
I can't hit my macros exactly every day — is that a problem?
No. The body doesn't keep daily books; the weekly average is what decides. A practical standard: keep protein above 90% of target on most days, hit total calories across the week, and don't worry about the daily swing between carbohydrate and fat. Chasing exact grams is, for most people, what eventually makes them stop tracking — and an abandoned perfect plan always loses to an average plan you keep.
How do I actually track the grams?
This is the hard part, because the calculation takes a second but tracking repeats every day. Three practical approaches: aim for a palm-sized protein source at every meal (roughly 25–30 grams), rotate the same three or four breakfasts (calculate once, reuse forever) and use photo recognition. FitDex takes the third route: you photograph the plate, the AI estimates the portion, splits it into protein, carbohydrate and fat and posts it against the target you calculated here. The calculation is the start; the work is in that daily repetition.
Related tools
- Calorie calculatorEnter your height, weight, age and activity level to see your daily calorie needs, basal metabolic rate and macro split in seconds. The same formula as the FitDex app.
- BMR calculatorWork out the energy your body spends doing nothing, using the Mifflin-St Jeor equation. Your total daily expenditure and water need come with it. The equation is written out in full — along with which part of it you can actually change.
- Body fat calculatorEstimate your body fat percentage and lean mass from height, weight, age and sex. We don't ask for a tape measure — and we explain why, along with the margin of error.
- Water intake calculatorWork out your daily water need from your weight. We also trace where the "eight glasses a day" rule came from and why it's been misread — the real indicator isn't a glass count, it's the colour of your urine.
This tool is for information only and is not a substitute for medical diagnosis or treatment. Talk to a healthcare professional before making a lasting change to how you eat.