Protein Calculator

Related Calculators

Selected goal target: Your main daily protein answer, shown in the unit selected under Show protein amounts as, based on the Goal you chose.

Minimum health target: A baseline protein amount for basic health needs. For many adults, this uses 0.8 g per kg of body weight or a life-stage reference amount.

Practical daily range: A low-to-high protein range that fits the chosen goal when a range makes more sense than one exact number.

Protein target intensity: Your target shown as grams of protein per kilogram of body weight per day, written as g/kg/day.

AMDR protein range: An optional calorie-based comparison that converts 10% to 35% of calories from protein into a daily protein amount for adults [2], shown in your selected output unit.

Life-stage reference amount: A table-based daily protein amount that can change with age, sex, and pregnancy or lactation status [2].

Mistake: Entering a value in Body weight (lb) while Body-weight unit is set to metric, or entering Body weight (kg) while it is set to US.
Fix: Use only the body-weight field that matches the selected Body-weight unit .

Mistake: Using 0 or a negative number for Body weight (lb) or Body weight (kg) .
Fix: Enter a positive body weight so the calculator can compute Selected goal target and Minimum health target .

Mistake: Choosing Pregnancy or lactation status for a non-female Sex selection.
Fix: Set Sex to female or change Pregnancy or lactation status to None.

Mistake: Choosing Pregnancy or lactation status with an Age group below adult years.
Fix: Use pregnancy or lactation only with adult Age group settings that support those life stages.

Mistake: Treating Minimum health target as the same thing as Selected goal target for muscle gain or an active lifestyle.
Fix: Read Minimum health target as a baseline and use Selected goal target for the goal you chose.

Mistake: Treating the calorie-based AMDR comparison as the goal you selected.
Fix: Use Selected goal target as the main answer. Turn on Show calorie-based AMDR comparison only when you want that separate reference.

• This calculator estimates daily protein targets from body weight, life stage, and goal. It does not account for medical conditions, kidney disease, injury recovery, or clinician-prescribed nutrition plans.
• The Minimum health target is a baseline, not a performance target. Active, muscle-gain, fat-loss, and older-adult goals can reasonably produce higher values.
• Life-stage reference amount uses fixed table values for some age and sex groups, so it may differ from weight-based formulas even when both are valid.
• AMDR protein range is shown only when you explicitly turn on its comparison, enter positive Calories per day (kcal), and select a supported adult age group.
• Pregnancy and lactation settings are only valid for female adult age groups in this calculator. Other combinations should be corrected before calculation.
• Displayed daily amounts are rounded for readability, so the visible answer may differ slightly from the internal math. Gram rounding applies only to g/day; ounces and pounds use fixed display precision.

How the calculator works

The calculator first gets body weight in kilograms. If you choose US units, it converts pounds to kilograms using the exact conversion 1 lb = 0.45359237 kg [2].

weight_kg = weight_lb / 2.2046226218

Next, it determines a baseline minimum. For many healthy adults, the baseline uses 0.8 grams of protein per kilogram of body weight per day [1]. For children, teens, and some adult life stages, the calculator can also use a table-based life-stage reference amount.

protein_min_g_day = 0.8 * weight_kg

Goal-based target

For adults, your Selected goal target is calculated from a goal factor in g/kg/day. For ages 1–18, this tool uses only the general life-stage reference; it does not prescribe muscle-gain, weight-loss, or athletic protein targets for children. The calculator uses one main factor for each goal so the primary answer stays simple and consistent.

protein_goal_g_day = factor_g_per_kg * weight_kg

Examples of goal styles used here are general health at 0.8 g/kg/day, active lifestyle from the sports-active range of 1.2 to 2.0 g/kg/day, muscle gain centered at 1.6 g/kg/day, fat-loss support at a higher active-style target, and older adult support centered at 1.1 g/kg/day [2][2].

Practical range

When a goal has a meaningful range, the calculator also shows Practical daily range by multiplying body weight by the low and high ends of that goal range.

protein_range_low = factor_low_g_per_kg * weight_kg

protein_range_high = factor_high_g_per_kg * weight_kg

For example, if body weight is 70 kg and the chosen muscle-focused target is 1.6 g/kg/day, then the main goal target is 112 g/day because 1.6 x 70 = 112.

AMDR comparison

If you turn on Show calorie-based AMDR comparison and enter Calories per day (kcal), the calculator can also show a separate calorie-based comparison using the adult AMDR for protein of 10% to 35% of calories [1]. Protein provides 4 kcal per gram [1].

protein_g_day = (calories_per_day * protein_percent) / 4

Mini-example:

with 2,000 kcal per day, the low end is (2000 x 0.10) / 4 = 50 g/day, and the high end is (2000 x 0.35) / 4 = 175 g/day.

How to read the outputs

Minimum health target is the baseline. Selected goal target is the main recommendation for the goal you picked. Protein target intensity tells you the same target in g/kg/day so you can compare methods more easily. Life-stage reference amount helps explain why some teen, adult, pregnancy, or lactation results come from table values instead of only body-weight math.

Assumptions used

This tool assumes body weight is a reasonable basis for protein guidance, uses fixed factors for clear goal targets, and applies adult AMDR comparison only where supported in the page logic. Real needs can differ with illness, training load, body-composition goals, and clinical advice.