How much protein you actually need per day
Updated: 2026-09-22
Searches for "protein in chicken breast" are up 232%, "protein powders" up 174% — everyone wants the number, not the ingredient list. The official RDA is 0.8 g/kg of body weight per day, and that's enough to avoid losing muscle in a sedentary life. For people who train, the bar is higher — and it has a measured ceiling, not just "more is better."
Protein target calculator
How much protein to eat per day given your weight, goal and training — a range from the Institute of Medicine RDA and the Morton et al. (2018) meta-analysis.
- Protein target
- — g/day
- Per meal
- —
At high body fat, lean body mass is the more accurate base than total weight — this calculator does not compute it.
The baseline is 0.8 g/kg
The Institute of Medicine sets the RDA at 0.8 g of protein per kg of body weight per day — the minimum that covers nitrogen balance for most adults who don't lift weights. At 80 kg that's 64 g of protein a day, roughly 2–3 palm-sized servings of animal or plant protein.
This is the number for an UNTRAINED body. It isn't built for muscle growth and isn't even optimal for preserving muscle in a calorie deficit or with age.
For building muscle, the ceiling is around 1.6 g/kg
Morton et al. (2018, Br J Sports Med) pooled 49 RCTs and 1,863 participants: protein supplementation alongside resistance training increased 1RM strength (+2.49 kg) and fat-free mass (+0.30 kg). But the effect plateaus, with a breakpoint around 1.62 g/kg/day and an upper confidence bound near 2.2 g/kg.
In practice: if you're eating 2.5 g/kg hoping for faster muscle growth, protein beyond roughly 1.6–2.2 g/kg per this meta-analysis doesn't build more muscle — the training response is already saturated at that intake.
Losing fat while keeping muscle — same range, pushed higher in practice
In a calorie deficit the body is more willing to burn muscle for energy if protein is short. The upper part of the same range — 1.6–2.4 g/kg — is common practice for protecting muscle mass while cutting. That upper bound isn't a number from the Morton meta-analysis; it's a widely used practical target for cutting while keeping strength.
Adults 65+ need to aim higher
The anabolic response to a given protein dose declines with age ("anabolic resistance"), so guidelines for adults over 65 tend to sit above the RDA. There isn't a single verified number to cite here — aim for the upper half of your range rather than the lower end.
Splitting it across meals, and how to check it on yourself
A practical rule (not from the Morton meta-analysis, just a common heuristic) is roughly 0.4 g/kg per meal across 3–4 meals a day, rather than the whole day's protein in one dinner: muscle protein synthesis responds to a serving, not the daily total.
You can check whether your target is working over 8–12 weeks: log your strength training (is your working weight going up on the same lifts?) and track body composition. Health OS has a workout log and weight tracking for exactly this — watch the trend, not a single weigh-in.
FAQ
Can I get all my daily protein in one meal?
You technically can, but muscle protein synthesis responds better to spread-out servings of roughly 0.4 g/kg per meal — that's a practical heuristic, not a result from the Morton meta-analysis, though it matches how protein response was measured in the individual trials that meta-analysis pooled.
If I eat 3 g/kg, will muscle grow faster?
Per Morton et al. (2018), no: the effect plateaus around 1.6 g/kg/day, with an upper confidence bound near 2.2 g/kg. Beyond that range, strength and fat-free mass gains from protein stop increasing.
I have a high body fat percentage — should I use total weight?
Total weight overstates your need when fat mass is high: lean body mass is the more accurate base. This calculator doesn't compute lean mass — use total weight as an approximation, or get a body composition estimate separately.