Protein Calculator

How your protein target is set

Protein is worked out from your bodyweight and your goal, then checked against your calorie target so the rest of the day still fits.

It is set first, before carbohydrate and fat, because it is the macro with the clearest reason to hold steady while calories move. When you eat less, the amount of protein you need does not fall with your calories.

• lose fat: 2.2 g per kg of bodyweight.
• recomp: 2.2 g per kg of bodyweight.
• maintain: 1.8 g per kg of bodyweight.
• build muscle: 2 g per kg of bodyweight.
• gain size: 1.8 g per kg of bodyweight.

A note on very high bodyweight

Above a BMI of 30 the calculator switches to an adjusted reference weight rather than your scale weight when setting protein and fat. Without that, grams per kilo scales into targets nobody could realistically eat.

This happens quietly and is not shown to you as a BMI figure, because your BMI is not a useful thing for a calculator to put in front of you.

How this compares with the Australian guidance

The Australian Nutrient Reference Values, published by the NHMRC and the New Zealand Ministry of Health, set the Recommended Dietary Intake for protein at 0.84 g per kg of bodyweight per day for men aged 19 to 70, which is 64 g per day, and 0.75 g per kg for women, which is 46 g per day.

This calculator targets more than that: between 1.8 and 2.2 g per kg depending on your goal. That is a deliberate difference, and it is worth understanding why rather than assuming one of the two figures is wrong.

An RDI is the amount that meets the needs of nearly everyone in the general population. It is a floor set to prevent deficiency, not a target chosen to support resistance training or to protect muscle while you are eating less than you burn. Those are different questions with different answers.

The same reference values set no upper limit for protein, stating that there are insufficient data to do so, while recommending a ceiling of 25% of energy from protein. This calculator caps protein at 35% of your calories, so on a lower calorie target it can sit above that recommended ceiling. If that matters to you, and it reasonably might, a dietitian is the right person to ask.

Source: Australian Nutrient Reference Values: Protein (NHMRC and NZ Ministry of Health)

Spreading it across the day

A daily total is easier to hit when it is broken into similar portions across three or four meals than when most of it is left to dinner. That is a practical observation about how people actually eat rather than a claim about absorption.

If you are eating plant based, reaching a higher protein target takes more planning, because the protein density of most plant foods is lower. Combining legumes, soy foods, grains and a protein powder through the day is the usual approach.

How these numbers are produced

Every figure on the results page comes from a fixed calculation, not from an AI guess. The same answers always produce the same numbers, which is why you can come back next month, enter the same details, and get the same targets.

An AI model writes the explanation you read underneath the numbers. It is given the figures after they have been calculated and it is not allowed to change them, recalculate them, or quote a figure the calculation did not produce.

• Resting energy is estimated with the Mifflin-St Jeor equation, or the Katch-McArdle equation if you tell us your body fat percentage, which is the more accurate of the two when that figure is known.
• Your activity multiplier comes from your weekly training sessions and how physical your work day is. The scale runs from 1.2 for sedentary to 1.9 for very high activity.
• We deliberately lean conservative on activity. Overestimating maintenance is the most common failure in consumer calculators, and it quietly makes every goal harder.

The limits built into this calculator

A calorie target handed to a stranger needs guardrails, so several are built in and cannot be overridden.

• Fat loss is capped at 1% of your bodyweight per week. Faster than that is not a setting you can choose here.
• Your calorie target never drops below the higher of your estimated resting energy and an absolute floor of 1500 calories for men or 1200 for women.
• There are no goal weight projections and no "you will reach X by this date" timelines, because those numbers are not knowable and they set people up to feel they have failed.
• If your details fall outside what a general calculator should answer, it stops and points you to a doctor or an Accredited Practising Dietitian instead of producing a number anyway.

What this calculator is not

This is general information. It is not personalised dietary advice and it is not medical advice. It cannot see your blood work, your training history, your medication or your relationship with food.

If you are managing a health condition, if you are pregnant or breastfeeding, if you have a history of disordered eating, or if you simply want targets built around your actual situation, speak to a doctor or an Accredited Practising Dietitian. That is a better use of your time than any calculator.