Daily protein references are different
There is no single protein number that fits everyone, and a calculator that shows only one hides that. This page shows three separate references for a healthy adult, side by side, so you can see how they differ. The first is the general adult reference, 0.8 grams per kilogram of body weight per day, which for 75 kg is 60 g. The second is a published range for adults who exercise, 1.4 to 2.0 grams per kilogram, which for the same weight is 105 to 150 g. The third is a factor you type yourself, 1.6 by default, giving 120 g. These numbers answer different questions. One describes a population minimum, one a range for people who train, and one is only arithmetic. The page never merges them into a single "optimal" figure and never picks the exercise range for you because you chose an activity level. Each has its own row.
The g/kg formula and units
All three references use the same formula: grams of protein per day = grams per kilogram × body weight in kilograms. If you enter pounds, the calculator converts with the exact constant 0.45359237 kg per pound before multiplying, so 165 lb is 74.8 kg and the general reference is 59.9 g. A factor of 1.6 g/kg on 75 kg is 1.6 × 75 = 120 g, which at 4 kilocalories per gram of protein supplies 480 kcal. Weight is the only body measurement needed for this part. Age, height and sex are asked for only if you turn on the energy comparison and choose to have your energy estimated. The weight accepted is 20 to 350 kg, and the custom factor can be any value above 0 and up to 4.0 with at most two decimals. These are limits of the tool, not statements about what is advisable. Anything outside the limits is rejected with a message.
General versus exercising-adult sources
The 0.8 g/kg figure is the adult Recommended Dietary Allowance. A position stand from the International Society of Sports Nutrition restates it as the amount estimated to meet the needs of nearly all, 97.5%, of healthy men and women aged 19 and over (ISSN, 2007). An allowance of that kind is set to prevent deficiency in a population. It is not a statement of the most useful amount for every person.
The 1.4 to 2.0 g/kg range comes from the Society's updated 2017 position stand, which concludes that this daily intake is sufficient for most exercising individuals who want to build or keep muscle (Jäger et al., 2017). It is a published range for healthy adults who train. It is not a prescription, it does not promise results, and it is not meant for people with kidney or liver disease or other conditions where protein needs are managed by a clinician. Your custom factor sits outside both sources. Use it to test a number a coach, dietitian or doctor has given you, not as a recommended limit.
Because the sources differ in purpose, two honest calculators can show different answers. Read the label beside each number.
Worked 75 kg and per-meal example
Take a 75 kg adult who chooses the custom factor 1.6 and three meals. The general reference is 0.8 × 75 = 60 g. The exercising range is 1.4 × 75 = 105 g to 2.0 × 75 = 150 g. The custom amount is 120 g, or 480 kcal. Spread equally across three meals, that is 40 g per meal. With four meals and a 1.2 g/kg factor at 60 kg, it is 72.0 g a day and 18.0 g per meal. Equal division is only arithmetic. The 2017 position stand discusses single-serving amounts of about 0.25 g/kg or 20 to 40 g for stimulating muscle protein synthesis, which is a separate question from daily totals, so this page does not call any per-meal number a maximum or a minimum.
At 1.2 g/kg the same 75 kg is 90 g, and at 2.0 g/kg it is 150 g, so the reference you choose matters.
Energy-percent comparison
An optional view compares protein with a share of daily energy. The Institute of Medicine, now part of the National Academies, gave an acceptable range for adults of 10% to 35% of energy from protein (summary in a sports-nutrition review). Turn the comparison on, enter your daily calories or have them estimated, and the page converts the range to grams by dividing by 4 kcal per gram. At 2,000 kcal, 10% is 50 g and 35% is 175 g, and the 120 g custom amount is 24.0% of that energy. If you ask for an estimate, the page uses the same resting-energy equations as the BMR calculator and the same six activity factors. For a full split of energy into protein, carbohydrate and fat, use the macro calculator.
The energy view is a cross-check, not a second target: the same 120 g is 24% of a 2,000 kcal day but 40% of a 1,200 kcal day.
Limits and food quality
This page is written for healthy adults aged 19 and over. It does not cover pregnancy, breastfeeding, children and teenagers, kidney or liver disease, diabetes or any condition in which a doctor or dietitian sets protein intake. It does not know what you currently eat, so it cannot say whether you get enough. It also does not say which foods to choose: amino acid mix, fiber, saturated fat and total diet quality all matter and are outside a gram calculator. Sources were read on 7 November 2026 and are reviewed at least once a year. Return to the Fitness & Health hub for the other tools.
Protein quality and the rest of the diet matter as much as the number. A gram figure cannot show whether the foods you choose suit your health.
Protein calculator questions
How do I calculate protein grams from my weight in kg?
Multiply your weight in kilograms by the grams per kilogram you want to test. For 75 kg at 1.6 g/kg that is 120 g a day. Pounds are converted to kilograms first, so the arithmetic is the same in either unit.
Does 0.8 g/kg mean that is everyone's best amount?
No. It is the adult reference allowance for healthy adults, set to meet the needs of nearly everyone in a population. It is not a claim about the best amount for each person. Population allowances are not personal prescriptions.
What about protein for muscle gain?
A published position stand gives 1.4 to 2.0 g/kg a day as sufficient for most exercising individuals building or keeping muscle. That is a range for healthy adults, not a guarantee of results or a prescription.
Is the per-meal amount a biological maximum?
No. The page divides your chosen daily amount equally across the meals you enter. That is arithmetic. Real meals vary, and the page makes no claim about the most protein the body can use at once. Equal division is a plain calculation.
Can illness or pregnancy change what I need?
Yes. Those situations are outside this calculator. Ask a doctor or registered dietitian who can look at your own circumstances.