Daily Protein Target Calculator

Protein is the one macronutrient most people get casually wrong — and the stakes rise with every decade. It is the raw material your body uses to build and defend muscle, and muscle is what keeps you strong, mobile, and metabolically healthy into old age. This calculator turns the research into a single daily number for your body and your goal, then shows you how to spread it across the day. Here's the thinking behind it.

Why protein matters more as you age

Muscle mass typically starts drifting down in midlife — a slow loss called sarcopenia that accelerates after 60 and, left unchecked, leads to weakness, falls, and lost independence. Two things drive it: doing less resistance exercise, and a phenomenon called anabolic resistance. Older muscle simply responds less to a given amount of protein, so the same chicken breast that fully "switches on" muscle-building in a 25-year-old does less in a 70-year-old. The fix isn't mysterious: older adults need more protein per meal and per day to get the same signal — which is exactly why the RDA, set decades ago, is widely considered too low for healthy aging.

Protein also helps in less obvious ways. It's the most satiating macronutrient, so it blunts hunger and makes fat loss easier. It supports bone, immune function, and recovery. And paired with strength training, adequate protein is the single most reliable lever for holding onto lean mass through midlife and beyond.

How much protein do you really need?

The official RDA is 0.8 grams per kilogram of body weight per day. But read the fine print: that figure is the minimum needed to prevent deficiency in nearly everyone — a floor, not a target. It was derived from short-term nitrogen-balance studies and says nothing about thriving, preserving muscle, or performing. The modern consensus, captured in this calculator's options, looks like this:

• General health & healthy aging: 1.0–1.2 g/kg. The PROT-AGE and ESPEN expert groups both landed here, and both were writing about healthy adults over 65 rather than adults in general.
• Older adults who are ill or recovering: 1.2–1.5 g/kg, to counter the muscle loss that comes with illness and bed rest. The tool doesn't offer this as a separate profile — it is the top of the range on the "Healthy adult 65+" option, which is why that end is labelled for people who train hard or are recovering, and why it belongs in a conversation with a clinician if you're unwell.
• Active people and exercisers: 1.4–2.0 g/kg, the range in the ISSN position stand. A 2018 meta-analysis found the benefits for resistance training plateau around 1.6 g/kg.
• Building muscle: 1.6–2.2 g/kg. The 1.6 floor is that plateau figure; the numbers above 2.0 are extrapolation past where the published ranges stop, not a guideline.
• Losing fat: 1.2–2.0 g/kg for ordinary dieters, because extra protein in a calorie deficit protects the muscle you'd otherwise burn alongside fat, and it keeps you full.

Pick the profile that matches your life and the calculator multiplies it by your weight. For most readers of a longevity site — adults who want to stay strong — somewhere between 1.2 and 1.6 g/kg is the sweet spot.

The one case that needs much more: lean athletes cutting weight

There is a population whose protein needs genuinely run far higher, and it is narrow. A 2014 systematic review by Helms and colleagues looked at lean, resistance-trained athletes dieting down for competition and landed on 2.3–3.1 grams per kilogram of fat-free mass — note the denominator. That is grams per kilo of lean mass, not of body weight, in people who are already lean and training hard, and it exists to defend muscle during an aggressive deficit. If that is you, work from your measured fat-free mass and those figures instead; the "Losing fat" profile here is built for the much larger group of people who are dieting while staying active, and it reports grams per kilo of total body weight.

How this calculator works

The core math is deliberately simple: protein (g/day) = body weight (kg) × factor, where the factor comes from the consensus ranges above. There's one important refinement. If you also enter your height and your BMI is 30 or higher, multiplying your full body weight by 1.8 or 2.0 would produce an unrealistic, sky-high target, because fat mass doesn't need feeding the way muscle does. So for higher-BMI users the tool switches to an adjusted body weight — an ideal weight at BMI 22.5 plus a quarter of the excess — and tells you when it does.

Be clear about what that adjustment is: a house heuristic, not a guideline. The 25%-of-the-excess rule comes from energy estimation in clinical nutrition, and the authorities that dose protein in people with obesity disagree with each other — ASPEN works from ideal body weight, ESPEN from an adjusted weight in critical illness, and neither has been validated for protein in healthy, free-living adults. It is a reasonable way to avoid an absurd number, nothing more. Because of that, the calculator also puts a floor under the result: it never returns less than the plain RDA of 0.8 g/kg of your actual weight. Your need for muscle-maintaining protein doesn't fall just because your fat mass rose.

Spread it across the day, don't save it for dinner

When you eat protein matters almost as much as how much. Each meal triggers a burst of muscle protein synthesis, but there's a threshold: you need roughly 0.4 grams per kilogram— the ISSN puts the practical window at 20–40 grams of high-quality protein — to maximize that burst, and a bit more as you get older to overcome anabolic resistance. Complete proteins (meat, fish, eggs, dairy, soy, whey) are richest in the amino acid leucine that triggers the response, which is why they hit the threshold in smaller portions.

The practical upshot: aim for three or four meals each carrying a solid 20–40 grams, rather than a token yogurt at breakfast and a giant steak at night. The typical Western pattern — almost no protein in the morning, a little at lunch, a pile at dinner — leaves muscle under-stimulated for most of the day. That's why this tool shows your daily target divided into per-meal portions: it's a target to hit at each sitting, not just a grand total.

Where to actually get it

Hitting these numbers is easier with a few anchor foods. As rough guides, each of these delivers about 20–30 grams of protein: a chicken breast, a can of tuna, a 4-ounce serving of lean beef or salmon, three or four eggs, a cup of Greek yogurt or cottage cheese, a scoop or two of whey, or a cup of cooked lentils plus grains. Plant-based eaters can absolutely hit the targets — it just takes attention, slightly larger portions (plant proteins are less concentrated and a touch less efficiently used), and combining sources like legumes, soy, and grains across the day. If you're consistently short, a protein supplement is one well-studied way to close the gap: the meta-analysis that produced the 1.6 g/kg plateau pooled trials of protein supplementation in people doing resistance training, so it is a format with real evidence behind it — it just can't do anything your meals were already doing.

Is high protein safe?

For people with healthy kidneys, the "protein wrecks your kidneys" warning is a myth that won't die. A 2018 meta-analysis of 28 controlled trials found no adverse effect of higher-protein diets on kidney function. Healthy bodies handle protein well across a wide range of intakes. There are two genuine caveats. First, if you already have chronic kidney disease, the rules flip — protein is often deliberately restricted under medical supervision, and PROT-AGE singles out older people with an eGFR below 30 mL/min/1.73 m² who aren't on dialysis as a group that may need to limit protein, so don't use any target here without talking to your doctor. Second, more isn't better: no authority sets a tolerable upper limit for protein, but there's no evidence of extra benefit for general health much above roughly 2.2 g/kg, and past the point your muscles can use it, protein mostly displaces other foods. The calculator doesn't impose an artificial ceiling — it shows you the published band for your goal and leaves the arithmetic visible.

Reading your result

The big number is your recommended daily target; the band beneath it shows where the published figures for your goal sit, low end to high end — it isn't a safe range with hard walls, and there's no need to hit the number to the gram. The per-meal portions are your real-world tool: aim to build each main meal around one of them. If you're new to tracking, spend a few days weighing or estimating what you currently eat — most people are surprised how far below target they start, and simply adding a protein-forward breakfast often closes most of the gap.

Common questions

Should I count protein on rest days too?

Yes. Muscle repair and growth happen between workouts, often peaking a day or two after training. Keep your intake steady every day, training or not.

Does the source of protein matter?

Somewhat. Animal proteins and soy are "complete" and rich in leucine, so they hit the muscle-building threshold in smaller portions. Other plant proteins work well too — you just need slightly more and a variety of sources. Total daily protein is what matters most.

Should I enter my lean body mass instead of my weight?

No. Every factor in this tool except the Helms athlete figures above is expressed per kilogram of total body weight, so entering lean mass would quietly cut your target by roughly a fifth. Enter your actual weight, add your height if your BMI is high, and let the adjusted-weight step do that job.

How does protein fit with the rest of my plan?

Protein feeds the muscle that powers your aerobic engine — pair this target with our VO₂ max calculator to track fitness, and with strength training twice a week. If a leaner waistline is your aim, our waist-to-height ratio check is a better gauge of progress than the scale, since higher protein helps you lose fat while keeping muscle.