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Free calculator · the Mealbird app’s own formula

Protein calculator: how much protein do you need a day?

Pick a goal, enter your body and how much you move. You get a daily protein target and the calories around it, with every line of the arithmetic shown so you can check it yourself.

Your goal
Sex
Height
Weight
How active you are
–g protein
–kcal / day

Pick your goal, your sex and how active you are to see your numbers, and every step that made them.

Get a week of meals that hits your protein, every day.

Mealbird’s setup runs this same formula, then plans seven days that each clear the number, checked by arithmetic over USDA data, and writes the shopping list.

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A general nutrition estimate, not medical advice.

How the numbers are worked out

Two targets, in the order the app shows them. Each protein step can only lower the plain grams-per-pound number, never raise it.

Calories

  1. Base burn. The Mifflin–St Jeor equation, the standard clinical estimate of what a body burns at rest: 10 × weight in kg + 6.25 × height in cm − 5 × age, then + 5 for men or − 161 for women.
  2. × how active you are. 1.2 mostly sitting, 1.375 lightly active, 1.55 active, 1.725 very active, 1.9 athlete. That is your day’s burn.
  3. The goal. 20% less to lose fat, the same to hold steady, 10% more to build muscle, to the nearest 50 kcal.

Protein

  1. The weight it counts from. To lose fat, the lower of your weight and the weight at BMI 25 for your height (25 × your height in metres, squared). BMI 25 is the top of the World Health Organization’s healthy range, and dietitians call that weight a reference body weight. To hold steady or build muscle, your own weight.
  2. Grams per pound. 1 g per lb (2.2 g per kg) to lose fat, 0.8 g per lb (1.8 g per kg) to hold steady, 0.9 g per lb (2 g per kg) to build muscle, to the nearest 5 g.
  3. At most 35% of calories. At 4 kcal a gram, rounded down to 5 g so it never passes 35%. But never under a floor: when losing fat, 0.8 g per lb of the reference weight; otherwise 1.2 g per kg of your weight, the bottom of the 1.2–2.0 g/kg range sports-nutrition bodies give for active adults.
Worked exampleMale, 30, 5′10″, 180 lb, active (3–4 workouts a week), losing fat: 175 g protein and 2,200 kcal a day. He is at BMI 25.8, so protein counts from 174 lb, the BMI 25 weight for his height, rather than 180.
  1. Base burn (Mifflin–St Jeor)1783 kcal10 × 81.648 kg (180 lb) + 6.25 × 177.8 cm (5′10″) − 5 × 30 years, + 5 for men. What your body burns at rest.
  2. × 1.55 active2763 kcalWhat you burn in a day: base burn × 1.55 for 3–4 workouts a week.
  3. − 20% for the cut2200 kcal2,763 kcal × 0.8, to the nearest 50 kcal.
  4. Weight at BMI 25 for your height174 lb25 × 1.778 m × 1.778 m = 79 kg (174 lb), the top of the WHO healthy BMI range. You weigh more, so losing fat counts protein from this weight instead.
  5. Protein: 1g × 174 lb175g1 × 174 lb = 174, to the nearest 5 g. Within 35% of your calories (up to 190 g), so this is your target.

Protein questions, answered

What people ask about protein targets, answered for the formula on this page. More about the app in the Mealbird FAQ.

How much protein do I need a day?

It depends on your weight and what you are eating for. The US recommended dietary allowance for adults is 0.8 g per kg of body weight a day (about 0.36 g per lb), and sports-nutrition bodies put active adults at 1.2 to 2.0 g per kg. This calculator uses 1 g per lb to lose fat, 0.8 g per lb to hold steady and 0.9 g per lb to build muscle, then checks the result against 35% of your calories.

Should protein be based on my current weight or my goal weight?

To lose fat, this calculator counts protein from whichever is lower: your weight, or the weight at BMI 25 for your height (25 × your height in metres, squared), the top of the WHO healthy range. Dietitians call that a reference body weight. At a higher weight, grams per pound of total weight can be more than half a day’s calories, which only the leanest foods can reach. To hold steady or build muscle, it counts from your actual weight.

Is 1 gram of protein per pound of body weight too much?

For a lean, active person it is a common gym target, a little above the 1.2 to 2.0 g per kg range for active adults (1 g per lb is 2.2 g per kg). For a heavier body it can be more than the day holds: 270 g for a 270 lb person eating 1,850 kcal is 58% of their calories. That is why this calculator uses 1 g per lb only to lose fat, counts it from the BMI 25 weight when you weigh more, and checks every target against 35% of calories.

Why is protein capped at 35% of calories?

So the day can still be made of ordinary food. Past about a third of the calories, only the leanest foods reach the number, and a week of meals shrinks to the same few dishes. The cap rounds down to 5 g so it never passes 35%, and it never goes below a floor: 0.8 g per lb of the BMI 25 weight when losing fat, or 1.2 g per kg of your weight otherwise, the bottom of the range for active adults. 35% is also the top of the 10 to 35% share of calories the US National Academies give for protein.

How many calories should I eat to lose fat?

This calculator starts from your base burn (the Mifflin–St Jeor equation, from your sex, age, height and weight), multiplies it by your activity level, from 1.2 for mostly sitting to 1.9 for an athlete, then takes 20% off to lose fat, keeps it level to hold steady or adds 10% to build muscle, to the nearest 50 kcal. It is an estimate: if your weight doesn’t move the way you expect over a few weeks, adjust from there.

Do women need less protein than men?

Not per pound: the grams per pound are the same for everyone. Sex changes the base burn, so a woman of the same size and age gets fewer calories a day, and the 35% cap can bring her protein down sooner on a small, low-calorie day.