Few nutrition topics cause as much quiet confusion as protein targets. A lifter in Texas reads that she needs 0.8 grams per pound of body weight; a lifter in Manchester reads 1.8 grams per kilo — and both are looking at roughly the same advice wearing different clothes. Because FitStudy Daily readers span the US, UK, Canada and Europe, we give every figure in both systems. The biology does not change at the Atlantic; only the arithmetic does.
Why two units exist
Scientific research is published in metric units, so studies describe protein in grams per kilogram of body weight (g/kg). American fitness media, written for an audience that weighs itself in pounds, converts those figures into grams per pound (g/lb). Neither is more correct. The conversion is simple: one kilogram equals 2.2 pounds, so any g/kg figure divided by 2.2 gives the g/lb equivalent. The well-known research target of 1.6 g/kg becomes 0.73 g/lb, and the old bodybuilding rule of ‘one gram per pound’ actually means a fairly aggressive 2.2 g/kg. Problems start when people mix the systems — applying a per-pound number to a weight they read off a metric scale, or the reverse, which can nearly halve or double the intended intake.
The numbers that matter
Three landmarks cover most people. The minimum to avoid deficiency for a sedentary adult is 0.8 g/kg per day, which is 0.36 g/lb. Regularly active people generally do well at 1.2–1.6 g/kg, or 0.55–0.73 g/lb. For maximising muscle gain during resistance training, research reviews converge on about 1.6 g/kg (0.73 g/lb), with a practical range up to 2.2 g/kg (1.0 g/lb) that some people prefer during a calorie deficit. Beyond that top figure, studies find no extra muscle benefit for most lifters — the surplus protein is simply used as expensive fuel. Note that the gram totals in the table below are identical whichever column you start from; only the rate used to calculate them differs.
Find yourself in the table
Targets below use 0.8 g/kg (0.36 g/lb) for the minimum, 1.4 g/kg (0.64 g/lb) for an active target, and 1.8 g/kg (0.82 g/lb) for a muscle-gain target. Find your weight in either unit and read across.
| Body weight (kg) | Body weight (lb) | Minimum (g/day) | Active (g/day) | Muscle gain (g/day) |
|---|---|---|---|---|
| 60 kg | 132 lb | 48 g | 84 g | 108 g |
| 70 kg | 154 lb | 56 g | 98 g | 126 g |
| 80 kg | 176 lb | 64 g | 112 g | 144 g |
| 90 kg | 198 lb | 72 g | 126 g | 162 g |
| 100 kg | 220 lb | 80 g | 140 g | 180 g |
Converting in your head
If a source gives you a figure in the ‘wrong’ unit, one shortcut covers it: to turn g/kg into g/lb, halve it and add a tenth back — or simply divide by 2.2 on your phone. Going the other way, multiply g/lb by 2.2. The same trick works for your body weight: pounds divided by 2.2 gives kilos (180 lb ≈ 82 kg), and kilos multiplied by 2.2 gives pounds (75 kg ≈ 165 lb). When a label, app or coach asks for your weight, check which unit the setting uses before entering it; this single settings toggle is the most common real-world source of protein targets that look absurdly high or low.
Choosing your target
Pick the row that matches your life, not your ambitions alone. If you train with weights three or more times a week and want to build muscle, the 1.6–2.2 g/kg band (0.73–1.0 g/lb) is the evidence-based choice. If you are active but maintaining, 1.2–1.6 g/kg (0.55–0.73 g/lb) is plenty. Older adults often benefit from the middle of the range because ageing muscle responds less strongly to protein. Whichever figure you land on, spread it across the day — roughly 0.4 g/kg (0.18 g/lb) per meal across four meals is a practical pattern — and remember the number is a daily average, not a pass-or-fail test.
