Macro calculator
Your daily calories, protein, carbs and fat in about 30 seconds. Free, and no sign-up needed.
14-day free trial. FuelKey turns these numbers into real meals and a daily checklist.
See how FuelKey worksHow it works
These are the same formulas FuelKey uses when you set up the app, so the numbers here match what your plan would start from. Training is counted separately from your job because a desk worker who lifts five days a week burns very differently from a nurse who doesn't train at all.
What macros are
Macros (macronutrients) are the three things food is made of that carry calories: protein, carbs and fat. Protein and carbs have about 4 calories per gram, fat about 9.
- Protein builds and keeps muscle and keeps you full. It matters most while losing weight, which is why it's set highest then: 1 gram per pound while losing, 0.9 while gaining, 0.8 while holding.
- Fat is set at 30% of your calories, a middle-of-the-road share that supports hormones and keeps meals satisfying.
- Carbs fill the rest. They fuel training and daily energy.
If you only track two things, track calories and protein. Within those, how you split carbs and fat matters much less, so lean toward what you can stick with.
Common questions
How accurate is a macro calculator?
Any formula is a starting estimate and can be off by 10% or more for a given person. The real test is your weight trend over two to three weeks. FuelKey's weekly review makes that adjustment for you from your own logs, in small steps, and asks before it changes anything.
How fast should I lose weight?
For most people, around 0.5 to 1% of bodyweight a week. The calculator suggests a pace from your weight and pulls it back if the target would drop below your resting burn or the usual safe minimum (1,200 calories for women, 1,500 for men). Faster than that tends to cost muscle.
How fast should I gain?
If the goal is muscle rather than fat, about a quarter to half a pound a week. Faster than about a pound a week, most of the extra arrives as fat.
Do I need to hit my carbs and fat exactly?
No. Get close on calories and protein, and let carbs and fat land where your meals put them.
What does FuelKey do with these numbers?
It builds a meal plan from real foods that hits your calories and protein, turns every day into a checklist you check off as you eat, makes the grocery list, and adjusts your targets each week from your actual results.
Not medical or dietary advice. These are estimates from standard formulas. If you are pregnant, under 18, have a medical condition or take medication that affects appetite or weight, check with your doctor before changing how you eat.