How much protein per day? Grams by body weight — and the cheapest way to hit it

"How much protein?" has two different answers depending on the goal, and conflating them is why the advice feels contradictory.

The RDA is a floor, not a target

The official RDA is 0.8 g of protein per kg of body weight per day. That number is set to prevent deficiency in the general population — it is not the amount that builds or preserves muscle. Using the RDA as a muscle-building target is the single most common mistake.

For muscle: about 1.6 g/kg

The most-cited synthesis here is a 2018 meta-analysis (Morton et al.) pooling resistance-training studies. It found protein intake boosted strength and muscle gains up to roughly 1.6 g/kg/day, after which more protein added little. Individual needs vary — some people benefit up to ~2.2 g/kg, especially when dieting or older — but 1.6 g/kg is the practical target for most people training for muscle.

In pound terms, 1.6 g/kg is about 0.7 g per pound of body weight.

Your number by body weight

Multiply your weight in kg by the factor:

• RDA floor (0.8 g/kg): 60 kg → 48 g · 70 kg → 56 g · 80 kg → 64 g · 90 kg → 72 g
• Muscle target (1.6 g/kg): 60 kg → 96 g · 70 kg → 112 g · 80 kg → 128 g · 90 kg → 144 g

(To convert pounds to kg, divide by 2.2. A 175 lb person is ~80 kg → ~128 g for muscle.)

Spread it across the day — roughly 20–40 g per meal is a sensible way to hit the total, though total daily intake matters most.

The cheapest way to close the gap

Whole foods should do most of the work; powder is just a convenient, cheap way to top up a shortfall. The key move when buying is to ignore the tub price and look at cost per gram of protein — a "cheaper" tub with 18 g per scoop can cost more per gram than a pricier one with 25 g.

• Whey concentrate is usually the best value per gram of protein.
• Isolate costs more for a marginally higher protein percentage and lower lactose — worth it mainly if lactose bothers you.
• Plant blends (pea/rice) are the pick for vegans; compare them on the same cost-per-gram basis.

We rank protein by cost per gram of actual protein on the protein hub, and the protein powder cost-per-gram guide walks through the math (methodology).

Bottom line

Use 0.8 g/kg only as the deficiency floor. To build or keep muscle, aim for about 1.6 g/kg/day (≈0.7 g/lb) — so ~112 g for a 70 kg person. Hit it with food first, top up with the powder that's cheapest per gram of protein, not per tub. Not medical advice.