Protein Intake Calculator

Three answers on one screen

Most calculators give you a number. This one gives you three, from three different authorities, and lets you watch them disagree.

Take a 30 year old man, 175 cm, 75 kg, training 3 to 5 times a week, aiming at moderate weight loss. His maintenance comes out around 2,633 calories, and the tool reports:

Three respectable bodies, three different answers, and the first one is so wide it spans a factor of three and a half. If you came here for a single number to write on your fridge, this looks like a mess.

It is not. Those three lines are not arguing. They are answering three different questions, and once you know which question each one is answering, the disagreement turns into the most useful thing on the page.

Why the first number is the lowest, and the most misunderstood

The National Academy of Sciences line comes from the Recommended Dietary Allowance, the famous 0.8 grams per kilogram figure. It is the most quoted protein number in the world and it is almost universally read as a target. It is not one.

Here is how an RDA is actually built. Researchers work out the intake at which people begin to run short. They take the average of that threshold across a group, then add two standard deviations on top, which pushes the figure high enough to cover about 97.5 percent of the population. That is the RDA.

So read what it really means. It is the amount that stops nearly everybody from becoming deficient. It is a floor with a safety margin bolted on, engineered to answer the question "how little can a person get away with", and it was never designed to answer "how much would be good for me". Reviews put it plainly: 0.8 g/kg is adequate to prevent deficiency and inadequate to support the demands of training.

Treating a deficiency threshold as a performance target is like treating the minimum wage as a salary recommendation. Technically nobody is starving. That is a different claim from anybody doing well.

The reason this particular line is so wide, from 52 g all the way to 184 g, is that the tool is showing you the full official band of 10 to 35 percent of calories rather than the 0.8 g/kg floor alone. As our Macro Calculator explains, that band is deliberately enormous because the evidence does not support anything narrower. A range that wide is honest. It is just not a target.

Why the athletes' number is nearly double

The second and third lines come from people asking a completely different question: not what prevents deficiency, but what supports someone who is actively breaking their body down and rebuilding it several times a week.

Training raises the rate at which you turn protein over. You break more down and you build more back, and if the incoming supply does not cover the increased traffic you sit in a small deficit that quietly costs you muscle. So the joint position of the Academy of Nutrition and Dietetics, Dietitians of Canada and the American College of Sports Medicine, published in 2016, puts active people at 1.2 to 2.0 grams per kilogram per day, and notes that higher intakes may be warranted during intensified training or when cutting calories. The International Society of Sports Nutrition lands in much the same place at 1.4 to 2.0.

Compare those to the floor. For our 75 kg man, 0.8 g/kg is 60 g. The athlete range is 90 to 150 g. Same body, two and a half times the spread, because the question changed.

Which of the three lines should you use? If you train, one of the bottom two. The RDA line is there for context and for the sedentary, and the honest answer is that most people reading a protein calculator are not asking the question the RDA answers.

What the goal setting does, and what it does not

Worth being straight about this, because it is not obvious from the screen.

Changing your nutrition goal moves the first line only. The National Academy figure is a share of your calories, so cutting your calories cuts it. The Academy and strength-training lines are calculated from your bodyweight and your activity, and they do not respond to the goal at all.

Two things follow. First, that is a limitation: protein needs go up in a deficit, not down, so the one line that reacts to your goal reacts in the wrong direction, while the two lines that should nudge upward stay put. We have flagged it. Second, it is a decent accident, because it means the bottom two lines give you a stable anchor that does not wobble every time you change your mind about how fast to lose weight. That anchor is the number to use.

Our Protein Calculator takes this apart in detail, because it is built on percentages and shows the problem in its own output rather beautifully.

Spreading it across the day

One thing a daily total hides: your body cannot bank protein. There is no reservoir to draw on later, so a day is not really one number, it is three or four separate opportunities.

The research on maximally stimulating muscle protein synthesis lands at roughly 0.25 to 0.40 grams per kilogram per sitting. For our 75 kg man that is about 19 to 30 g per meal. Go much beyond that in one go and the extra is still used, just not for the thing you were hoping for.

The practical version: if your target is 130 g, four meals of 30 to 35 g will serve you better than a token breakfast, a sandwich, and 90 g of chicken at nine in the evening. Most people are not short of protein overall so much as they are short of it until dinner.

Questions people ask

Which of the three numbers should I use?

If you train, the strength-training line, or the upper half of the Academy line. If you are sedentary and not trying to change your body, the Academy line is plenty. The National Academy figure is a floor, not a goal.

Why do the authorities disagree?

They do not, really. One is answering "what stops deficiency" and the others are answering "what supports training". Different questions, different answers, both correct.

Do I need more protein when I am dieting?

Yes, and this is one of the few things in nutrition that is not seriously argued about. A deficit puts your muscle at risk, and protein is the main thing defending it. Aim at the upper end of the range while you cut.

Is high protein bad for my kidneys?

In people with healthy kidneys, the evidence does not support that worry at the intakes discussed here. If you have existing kidney disease, that is a different situation entirely and one for your doctor rather than a calculator.

References

Where the figures come from. The 0.8 g/kg Recommended Dietary Allowance, and the definition of an RDA as the mean threshold plus two standard deviations covering 97.5 percent of people, are set out in the Institute of Medicine's Dietary Reference Intakes and in the trial report by Gaubert and colleagues. The 1.2 to 2.0 g/kg range for active people is the joint position of the Academy of Nutrition and Dietetics, Dietitians of Canada and the American College of Sports Medicine. The point that the RDA is adequate to prevent deficiency but inadequate for training, and the per-meal dose for maximally stimulating muscle protein synthesis, come from recent reviews.

1. Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: nutrition and athletic performance. Journal of the Academy of Nutrition and Dietetics. 2016;116(3):501-528.
2. Current perspectives on protein supplementation in athletes: general guidance and special considerations for diabetes. Nutrients. 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC12655512/
3. Treatment of metabolic syndrome by combination of physical activity and diet needs an optimal protein intake: a randomized controlled trial. Nutrition Journal. 2012;11:72. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3502154/
4. National Academies of Sciences, Engineering, and Medicine. Dietary Reference Intakes for Energy. Washington DC: The National Academies Press. https://www.ncbi.nlm.nih.gov/books/NBK591020/
5. Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition. 1990;51(2):241-247. https://doi.org/10.1093/ajcn/51.2.241