Protein Calculator
A protein calculator estimates how much protein you may want in a day based on body weight and a simple training goal. Enter your weight, choose kilograms or pounds, then select whether your current focus is maintain, build, or cut. The result gives you an estimated daily protein target in grams plus a practical planning range so you can turn the number into meals, snacks, or grocery choices more easily. This protein calculator is most useful for general fitness planning when you want a quick starting point without building the math from scratch every time your weight or goal changes.
Quick answer
The calculator first converts body weight to kilograms if you enter pounds.
What this tells you
- •The calculator first converts body weight to kilograms if you enter pounds.
- •It then applies one goal multiplier: 1.2 g/kg for maintain, 1.6 g/kg for build, and 1.8 g/kg for cut.
- •The displayed target is rounded to the nearest whole gram per day for easier meal planning.
- •The low and high values create a simple planning range by moving 0.2 g/kg below and above the selected multiplier.
- •This is a general body-weight method, so it does not estimate protein from lean mass, age, training volume, or medical nutrition needs.
How to Use
- 11. Enter your current body weight. Use the weight you want to plan meals around today, not an old number from months ago.
- 22. Choose the weight unit. Pick kg if your weight is already metric or lb if you track body weight in pounds.
- 33. Select your goal. Maintain uses the lightest multiplier, build uses a middle range for muscle-focused training, and cut uses the highest multiplier in this tool.
- 44. Calculate to see your estimated protein grams per day along with a lower and higher planning number.
- 55. Use the result to spread protein across meals and snacks. If your eating pattern, recovery, or medical history makes the number feel off, treat it as a starting estimate and review it with a registered dietitian or other qualified clinician.
How It Works
Formula
If weight is in pounds: weight in kg = weight in lb × 0.45359237
Protein target = weight in kg × goal multiplier
Planning range = weight in kg × (multiplier - 0.2) to weight in kg × (multiplier + 0.2)The formula in `lib/formulas/protein-calculator.ts` uses three fixed multipliers. Maintain uses 1.2 grams per kilogram, build uses 1.6 grams per kilogram, and cut uses 1.8 grams per kilogram. If you enter pounds, the calculator converts that weight to kilograms first by multiplying by 0.45359237. It then multiplies body weight in kilograms by the goal multiplier to get the main daily target. The low and high range values are not separate nutrition models. They are a simple planning band built by subtracting 0.2 g/kg from the chosen multiplier for the low value and adding 0.2 g/kg for the high value. Every displayed result is rounded to the nearest whole gram, which is why the final answer may differ slightly from the raw decimal math.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
75 kg with a build goal
Build uses the 1.6 g/kg multiplier. For 75 kg, the main target is 75 × 1.6 = 120 grams per day. The planning range uses 1.4 to 1.8 g/kg, so 75 × 1.4 = 105 and 75 × 1.8 = 135. This is a clean example because all three values land on whole numbers before rounding.
150 lb with a maintain goal
The calculator converts 150 pounds to kilograms first. 150 × 0.45359237 = 68.0388555 kg. Maintain uses 1.2 g/kg, so the main target is 68.0388555 × 1.2 = 81.6466266, which rounds to 82 g/day. The range uses 1.0 to 1.4 g/kg, so the low value rounds from 68.0388555 to 68 and the high value rounds from 95.2543977 to 95.
92 kg with a cut goal
Cut uses the highest multiplier in this tool at 1.8 g/kg. For 92 kg, the main target is 92 × 1.8 = 165.6, which rounds to 166 grams per day. The range uses 1.6 to 2.0 g/kg, so the low end is 92 × 1.6 = 147.2 and the high end is 92 × 2.0 = 184. That becomes a displayed range of 147 to 184 g/day after rounding.
135 lb with a build goal
First convert 135 pounds to kilograms. 135 × 0.45359237 = 61.23496995 kg. The build target is 61.23496995 × 1.6 = 97.97595192, which rounds to 98. The lower and upper planning values use 1.4 and 1.8 g/kg, giving 85.72895793 and 110.22294591, which display as 86 and 110.
60 kg with a maintain goal
Maintain uses 1.2 g/kg, so 60 × 1.2 = 72 grams per day. The range for this goal uses 1.0 to 1.4 g/kg, which gives 60 grams on the low end and 84 grams on the high end. This kind of result is easy to split into three or four eating occasions, which is why many people use the range instead of treating one exact number as the only acceptable target.
Goal multipliers used by this protein calculator
These are the fixed assumptions used in the formula, along with the simple planning band shown in the results.
| Goal | Main multiplier | Displayed range | What the setting is for |
|---|---|---|---|
| Maintain | 1.2 g/kg | 1.0 to 1.4 g/kg | General maintenance and baseline intake planning |
| Build | 1.6 g/kg | 1.4 to 1.8 g/kg | Muscle-focused training and growth planning |
| Cut | 1.8 g/kg | 1.6 to 2.0 g/kg | Fat-loss phases where preserving lean mass is a common priority |
These values are tool assumptions, not universal clinical rules. A coach or dietitian may choose different targets based on training load, body composition, appetite, or medical history.
How to use the result in real life
A daily protein target works best when it becomes a meal pattern, not just a single number on a screen. If your result is 120 grams per day, you might split it into four meals with about 30 grams each, or three meals plus one snack that together add up to the same total. The exact pattern matters less than hitting a reasonable total consistently.
The planning range is useful because most people do not eat the exact same amount every day. Appetite shifts, restaurant meals vary, and training days can feel different from rest days. Staying somewhere inside the range often gives you enough structure without turning the number into a source of unnecessary stress.
Food labels list protein by serving, so the result is easiest to use when you compare it with foods you actually eat. Greek yogurt, cottage cheese, eggs, fish, chicken, tofu, tempeh, edamame, beans, and protein powders can all help fill gaps. The most practical choice is usually the one you can repeat consistently, tolerate well, and fit into your budget.
This tool also keeps body weight at the center of the estimate, which makes it simple but limited. Two people at the same weight can have very different training volume, muscle mass, age, or recovery demands. That is why the result should guide planning, not replace a more complete nutrition assessment when the decision carries health consequences.
Common mistakes
- Using the wrong unit and entering pounds while kg is selected, or the reverse.
- Treating the rounded result as if it were an exact biological requirement instead of a practical estimate.
- Ignoring the planning range and assuming every day must match one precise gram total.
- Basing intake only on a goal label without considering appetite, food tolerance, training volume, and overall calorie intake.
- Using the result as medical nutrition advice when kidney disease, pregnancy, eating-disorder history, or other clinical factors may change what is appropriate.
Limitations
This estimate uses only body weight, unit conversion, and one of three fixed goal multipliers. It does not adjust for age, sex, body-fat percentage, lean mass, training frequency, activity level, calorie intake, injury recovery, digestive tolerance, medications, pregnancy, breastfeeding, or diagnosed medical conditions. The range is a planning convenience built around the selected multiplier, not an evidence-based individualized prescription band. If you need a target for kidney disease, liver disease, diabetes management, surgery recovery, competitive athletics, or disordered-eating recovery, this tool is too simple to replace a personalized assessment.
Embed this calculator on your site
Drop this single line where you want the calculator to appear. It is responsive, mobile-friendly, resizes automatically, and is free to use with attribution.
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