Enter 180 pounds with "Build muscle" selected and the calculator above returns 155 grams a day, inside a range of 130 to 180. The range is a published grams-per-kilogram band scaled to your bodyweight. The headline number is the middle of that range rounded to the nearest 5 grams, and the figure beside it is the same target divided across four meals.
So the arithmetic is settled in one step. What a calculator cannot decide is where inside a 50-gram range your own target belongs, or when bodyweight is the wrong number to scale from at all. The first of those is a 50-gram spread. The second can move the answer by more.
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Protein calculator
Scale a published grams-per-kilogram range by your bodyweight and goal to get a daily protein target you can actually hit.
Daily protein target
155 g/day
- Reasonable range
- 130–180 g
- Across 4 meals
- ~39 g each
These are population-level ranges scaled by bodyweight, not a personal prescription. If you carry a lot of fat mass, the lower end of each range is usually the better starting point, because protein needs track lean mass more closely than total weight. Talk to a clinician before raising protein sharply if you have kidney disease or another medical reason to limit it.
How to calculate your protein intake
The method is three lines, and seeing it once tells you what any protein intake calculator is doing:
- Convert your bodyweight to kilograms. Divide pounds by 2.2. A 180 lb lifter is about 82 kg.
- Pick the band that matches what you are doing. 1.2 to 1.6 g/kg if you are active but not training for size, 1.6 to 2.2 g/kg if you lift and are eating at or above maintenance, 1.8 to 2.7 g/kg if you lift while dieting. The table below gives the source for each.
- Multiply both ends of the band. 82 × 1.6 = 131 grams, and 82 × 2.2 = 180 grams. That range answers "how much protein do I need to build muscle" for that lifter.
If you think in pounds and want to skip the conversion, multiply your bodyweight in pounds by 0.7 to 1.0 grams per pound instead. Same answer, one step fewer, with the higher end when you are dieting.
Then round. 150 grams is a target you can aim at and 147.6 is not, which is why the calculator rounds to the nearest 5. Its "across four meals" figure is just the target divided by four, an assumption about your day rather than a recommendation about meal timing; how much protein per meal works through the split and the 30-gram absorption question behind it.
How much protein per day, by goal
The three bands are conventional coaching ranges scaled by bodyweight. They are starting points, not prescriptions.
| Your situation | Daily protein | Where the range comes from |
|---|---|---|
| Active, not training for size | 1.2–1.6 g/kg | Comfortably above the basic adult requirement, without chasing muscle gain |
| Lifting, at maintenance or in a surplus | 1.6–2.2 g/kg | A meta-analysis of protein and resistance training found gains in lean mass stopped improving past about 1.62 g/kg/day |
| Lifting in a calorie deficit | 1.8–2.7 g/kg | A review of lean athletes in caloric restriction recommends 2.3–3.1 g/kg of fat-free mass, which lands near this band once you scale it to the total bodyweight of a reasonably lean lifter |
None of this is medical advice. If you have kidney disease or another reason to limit protein, the target belongs in a conversation with a clinician rather than with a calculator.
Where in the range should you aim
The bands are wide because the evidence under them is. The meta-analysis behind the muscle-gain row put the intake where extra protein stopped adding lean mass at about 1.62 g/kg per day, which is the bottom of that band, not the top. Its confidence interval ran from roughly 1.0 to 2.2 g/kg, so the finding marks out a region rather than a line.
Read practically, that makes the bottom of the muscle band the target and the rest headroom. A 180 lb lifter who eats 130 grams every day is in better shape than one who aims at 180 and averages 120.
Dieting is the clearest reason to sit higher. The review behind the deficit row raises its recommendation as an athlete gets leaner and as the deficit gets larger, because both increase the pressure on muscle tissue, so a long or aggressive cut is the case for the top of that band rather than the bottom. Appetite is a second reason: protein is the most filling macronutrient, so when hunger is what breaks your diet, calories spent here are doing two jobs.
What argues for staying lower is the calorie cost. Protein carries 4 calories per gram, the same as carbohydrate, so an extra 60 grams is 240 calories that could have fuelled training or gone into the deficit instead. Past the top of a band, that trade rarely pays.
When bodyweight is the wrong input
The bands are written against total bodyweight, and they were derived in people at ordinary training body-fat levels. Protein needs track lean tissue. Fat mass does not need feeding in proportion, so scaling by total weight drifts once fat is a large share of it.
The review behind the deficit row states its recommendation in the more honest units: 2.3 to 3.1 grams per kilogram of fat-free mass, meaning your bodyweight minus your fat mass. What that converts to per kilogram of total bodyweight depends entirely on your body composition. For a 250 lb (113 kg) lifter in a deficit:
| Body fat | Lean mass | 2.3–3.1 g/kg of lean mass | The same target per kg of total bodyweight |
|---|---|---|---|
| 15% | 212 lb (96 kg) | 222–299 g | 1.96–2.64 g/kg |
| 25% | 188 lb (85 kg) | 196–264 g | 1.73–2.33 g/kg |
| 35% | 162 lb (74 kg) | 170–229 g | 1.50–2.02 g/kg |
The calculator takes bodyweight only, so it returns 205 to 305 grams for that lifter whatever their composition. At 15% body fat that is about right. At 35% it sits roughly 75 grams above the lean-mass figure at the top of the range, and the lean-mass math lands in a band lower than the one the goal selector chose.
Neither number is precise. A body-fat percentage from a smart scale or a photo comparison is itself an estimate, so this refines one approximation with another and is only worth the step when fat mass is high enough to move the answer, not to choose between 12% and 15%. And the fat-free-mass numbers come from lean athletes preparing for competition, so using them at 35% body fat is an extrapolation that argues for the lower end of the arithmetic rather than a studied recommendation.
Where the protein number sits in your other targets
Protein is one of four numbers, and it is the one worth fixing first because the others get built around it.
- Maintenance calories. What you burn in a day. The TDEE calculator guide estimates it, and better, back-calculates it from what you have eaten and what your weight then did.
- Your calorie target. Maintenance minus a deficit if you are cutting, or a little above it if you are gaining. The calorie deficit calculator sizes that subtraction from your bodyweight instead of defaulting to a flat 500.
- Protein. This page. Set it as a fixed floor, not as a share of whatever calories are left.
- Carbs and fat. Whatever remains, split to suit your appetite and your training. The macro calculator handles that division.
The order matters most while dieting, because that is when the calorie budget is tight enough for protein to get squeezed, and a deficit is exactly the situation where losing protein costs you muscle. If you are trying to lose fat and gain muscle at once, the body recomposition guide covers why protein decides what the weight you lose is made of.
Hitting the number, and knowing whether you did
A target is a number until something counts against it. Tell ChatRPE the target once and every meal you report updates a running total you can ask for before the last meal of the day. The protein tracker guide covers that workflow, including how to log without weighing everything.
Protein misses happen late in the day, which is the argument for a reminder rather than a resolution. Ask for a daily check at a time when you can still change dinner, and attach a condition to it: if today's logged protein already adds up to more than your target, that day's reminder is skipped instead of sent. The condition is evaluated against your entries at delivery time, and the schedule rolls on to tomorrow. Reminders arrive as push notifications through the iPhone app, so on other platforms the running total is something you ask for rather than something that finds you.
"Remind me at 4 p.m. on days my logged protein is still under 160 grams, and skip it on days I've already got there."
The other setup worth doing is a number you can read without asking for it. A saved dashboard can hold a single card showing today's protein total, or the grams you have left, which is your target minus today's total. That card stops at zero rather than counting into negatives, so it answers what is left and not how far past the target you went. On iPhone the same card can sit on the home screen and refreshes in the background as meals land. The fitness dashboard guide covers building one.
Check the band against what you actually ate
After a month of logs there is a better question than what the band predicted: what did you average, in the units the band is written in? ChatRPE can chart your daily protein totals with bodyweight on a second axis and a third series dividing one by the other, which is your achieved grams per kilogram, day by day. Put a reference line on that series at the bottom of your band and the gap stops being theoretical.
"Chart my daily protein next to my bodyweight for the last three months, add a series for grams per kilogram, and draw a reference line at 1.6."
The division uses whatever unit you log bodyweight in, so log kilograms if you want grams per kilogram, and read the result as grams per pound otherwise. A weekly weigh-in also has to be carried across the days between weigh-ins for the division to have a value every day, which is a fill setting on the chart rather than real daily data.
If you ask for the numbers instead of the chart, the analysis reads a recent window of up to 500 entries rather than your whole archive, so name a date range when you are reviewing months. The trend it reports compares the first half of that window against the second half and rounds the change to a whole percent, which points at where to look rather than settling the question.
That comparison is also the honest way to revise the target. A population band described you on the day you ran it, at a bodyweight and a training volume that have since moved. If your lifts stalled while protein averaged 40 grams under target for a month, that is worth acting on before the band is worth re-reading. For muscle gain specifically, protein is one of three levers, and how to build muscle covers how it fits with progressive overload and the size of the surplus. For fat loss, the weight loss tracker guide covers reading the weight trend and the intake data together.
Frequently asked questions
How do I calculate how much protein I need?
Convert your bodyweight to kilograms (pounds ÷ 2.2), multiply by the grams-per-kilogram band that matches your goal (1.2 to 1.6 if you are active, 1.6 to 2.2 if you lift, 1.8 to 2.7 if you lift while dieting), then round the result. In pounds, the same math is bodyweight × 0.7 to 1.0. The calculator on this page runs it for the goal you select and shows both the range and a starting number inside it.
How much protein should I eat a day to lose weight?
More than you need at maintenance, not less. A calorie deficit is the situation where your body is most willing to break down muscle for fuel, so dieting is when protein does the most work. The review of lean athletes in caloric restriction linked above recommends 2.3 to 3.1 g/kg of fat-free mass, which for a reasonably lean lifter works out near the 1.8 to 2.7 g/kg of bodyweight band in the calculator. Protein is also the most filling macronutrient, which is a useful side effect when calories are tight.
How many grams of protein per pound of bodyweight should I eat?
About 0.7 to 1.0 grams per pound for most people who lift, leaning toward 1.0 while dieting. "One gram per pound" persists because it is easy to remember and it lands inside the supported range for anyone at a typical body-fat level. It is a rounding convenience rather than a separate finding.
Should I calculate protein from my goal weight instead of my current weight?
It is a workable shortcut when you have no body-fat estimate, because goal bodyweight stands in for the lean mass you are trying to keep. For a 250 lb lifter in a deficit, a 190 lb goal weight run through the 1.8 to 2.7 g/kg band gives 155 to 233 grams, close to the 170 to 229 grams that calculating from lean mass at 35% body fat produces. If you do have a body-fat number, use lean mass and skip the proxy.
Do I need to hit my protein target exactly every day?
No. Weekly averages matter more than any single day, and a day 20 grams short is noise. The reason to count it anyway is that untracked misses are rarely 20 grams. They tend to be 60, several days a week, and invisible without a total.
How much protein do I need if I don't lift?
Less than a lifter, but probably more than you are eating. The calculator's lowest band, 1.2 to 1.6 g/kg, is the usual starting point for an active adult who is not training for size, which sits comfortably above the basic requirement. If you are losing weight without training, protein does more work than usual, because it is the main thing standing between a deficit and lost muscle; losing weight without exercise covers that case.
Can ChatRPE adjust my protein target as my weight changes?
Yes. Your target, your logged intake, and your bodyweight trend all live in the same Universal Logbook, so you can ask it to review the last month and revise the number rather than re-running a calculator against a bodyweight that has since moved. Ask for the grams-per-kilogram chart too and the revision has your own average in it, not a population band.