What a day of protein actually costs, by food

The arithmetic, spelled out once

Oats sit at $0.089 per 10 g of protein. Fifteen units gives 15 times 0.089, which is 1.335, so about $1.34 a day. Times 7 is $9.35 a week. Times 30 is $40.05 a month.

Ground beef 90/10 sits at $0.550 per 10 g of protein. Fifteen units is exactly $8.25 a day, $57.75 a week, $247.50 a month.

The spread between those two is $207.45 a month, or about $2,489 a year at 12 months. That is the headline number, and it is worth sitting with before anyone argues about brands. Nothing else on this page will move your grocery bill as much as which end of that range your protein comes from.

Neither extreme is a real diet. Oats at 16.9 g protein per 100 g would require about 888 g of dry oats a day to reach 150 g of protein. That is the point of the exercise: the endpoints bound the problem, and your actual cost lands somewhere inside them.

Three tiers, from $40 a month to $248 a month

Under $4 a day: oats at $1.34, peanut butter at $3.30, lentils at $3.33, tofu at $3.53, black beans at $3.71. Monthly, that band runs $40.05 to $111.15.

Between $4 and $5.50 a day: cottage cheese at $4.10, whey at $4.68 per 150 g of protein (6.25 scoops, since one 30 g scoop carries 24 g), edamame at $5.00, Greek yogurt at $5.25, 2% milk at $5.30, eggs at $5.36. Monthly, $122.85 to $160.65.

Above $6 a day: chicken breast at $6.00, canned tuna at $6.35, turkey breast at $6.57, tilapia at $7.13, ground beef at $8.25. Monthly, $180.00 to $247.50.

The useful read is that the tier boundaries matter more than the position inside a tier. Moving from tier three to tier two for a third of your protein saves real money. Agonising over lentils versus tofu, three cents apart per 10 g, does not.

The calorie bill that comes attached

Cost per gram of protein is only half the decision. Each food also carries a calorie cost, and the cheap end of the table is the expensive end on calories. Multiply the kcal per gram of protein by the grams you plan to take from that food.

At 150 g of protein from a single source: oats would be 3,450 kcal, peanut butter 3,525 kcal, black beans 2,220 kcal, milk 2,205 kcal. At the other end, canned tuna is 675 kcal, turkey 690 kcal, tilapia 720 kcal, whey 750 kcal, chicken 795 kcal.

That is why the $1.34 oats figure is a floor, not a plan. It is also a usable rule. If you want 30 g of protein from oats, that is 30 times 23.0, so 690 kcal. The same 30 g from Greek yogurt is 30 times 5.9, so 177 kcal. Same protein, 513 kcal of difference, and the yogurt version costs $1.05 against $0.27.

So the real question is not which food is cheapest, it is how much cheap high-calorie protein your day has room for.

What a realistic 150 g day actually costs

Build a mixed day and price it line by line. 100 g dry oats (16.9 g protein, 389 kcal, $0.15), one 30 g whey scoop (24 g, 120 kcal, $0.75), 200 g Greek yogurt (20 g, 118 kcal, $0.70), 100 g eggs which is about 2 large (12.6 g, 143 kcal, $0.45), 200 g cooked lentils (18 g, 232 kcal, $0.40), 200 g raw chicken breast (45 g, 240 kcal, $1.80), and 80 g tofu (13.6 g, 115 kcal, $0.32).

That totals 150.1 g of protein, 1,357 kcal, and $4.57. Weekly $31.99, monthly $137.10. Against an all-chicken day it saves $1.43 daily, or $42.90 a month, and costs 562 extra calories. Against an all-beef day it saves $110.40 a month.

Push cheaper and the trade-off shows immediately. Oats 100 g, lentils 300 g, tofu 200 g, black beans 200 g, peanut butter 40 g, milk 300 g, cottage cheese 100 g, and one whey scoop gives 150.9 g of protein for $3.62 a day, $108.60 a month, but 1,878 kcal. You saved $28.50 a month and spent 521 more calories to do it. That is the actual exchange rate between the two currencies.

Where the sticker price lies to you

Milk is the cheapest item on this table at $0.12 per 100 g. It is also tenth of sixteen on protein cost, at $0.353 per 10 g, because it is only 3.4 percent protein. Hitting 150 g from milk alone would take about 4.4 kg a day.

Tilapia costs $0.95 per 100 g raw and canned tuna costs $1.10. The cheaper package is the more expensive protein: $0.475 versus $0.423 per 10 g, because tuna carries 26 g per 100 g against tilapia's 20 g. Choosing on shelf price gets this backwards.

Whey runs the opposite way. At $0.75 a scoop it looks like the premium item, but per 10 g of protein it is $0.312, cheaper than eggs, milk, Greek yogurt, chicken, and everything in tier three, at 5.0 kcal per gram of protein.

One more correction. Chicken, turkey, tilapia, and ground beef are listed raw. Cooking drives off water, so if you plan portions in cooked grams you will buy more raw grams than the number suggests, and your true cost per gram of cooked protein is higher than the raw row implies. Canned tuna in water is not raw, so no such adjustment applies.

Why the ranking outlives the prices

If every price on this table rose 20 percent tomorrow, every daily figure would rise 20 percent and the order would not change at all. Rankings only flip when two foods are already close and then move differently.

Look at where that is plausible. Peanut butter at $0.220, lentils at $0.222, tofu at $0.235, and black beans at $0.247 sit within about 12 percent of each other. A single sale reorders them. Greek yogurt at $0.350, milk at $0.353, and eggs at $0.357 are within 2 percent, which is a tie in practice, so break it on calories instead: 5.9, 14.7, and 11.3 kcal per gram of protein respectively.

Now look at where it is not plausible. Oats at $0.089 against ground beef at $0.550 is a factor of about 6.2. No local price variation you will encounter closes that. Treat gaps under roughly 10 percent as noise and gaps over 50 percent as real.

Run it on your own store, and start with one swap

The change with the best ratio of savings to effort is a single substitution inside tier three. Ground beef to chicken breast saves $2.25 a day, which is $67.50 a month, and drops 525 kcal at the same 150 g of protein. Tilapia to canned tuna saves $0.78 a day, or $23.40 a month.

Shifting 50 g of a chicken-based target to lentils costs 5 times $0.222, so $1.11, against 5 times $0.400, so $2.00. That saves $0.89 a day, $26.70 a month, and adds 380 kcal, since 50 g from lentils is 645 kcal against 265 kcal from chicken. Decide whether your day has 380 spare calories, then decide.

Then replace our estimates with yours. Take a receipt, divide the package price by the grams of protein in the package, multiply by 15 for a 150 g target, and compare against the numbers above. Enter your own prices in the tool and it recomputes the whole ranking. Where your store disagrees with this table, your store wins.

FAQ

How is the daily protein cost calculated?

Each food has a cost per 10 g of protein. A 150 g daily target is 15 of those units, so the daily cost is 15 times that figure, the weekly cost is that daily figure times 7, and the monthly cost is the daily figure times 30. For example, oats at $0.089 per 10 g work out to $1.34 a day, $9.35 a week, and $40.05 a month.

What is the cheapest way to hit 150 g of protein a day?

On this data oats are cheapest per gram of protein at about $1.34 a day, followed by peanut butter at $3.30, lentils at $3.33, tofu at $3.53, and black beans at $3.71. None of those works as a sole source, because 150 g of protein from oats alone would be about 888 g of dry oats and 3,450 calories. A practical low-cost mix of oats, lentils, tofu, beans, peanut butter, milk, cottage cheese, and one whey scoop reaches about 151 g of protein for $3.62 a day, at 1,878 calories.

Are these prices what I will actually pay at my store?

No. They are maintained, representative US grocery estimates joined to public nutrition data, not live or store-specific prices, so the absolute dollar figures will drift with your location, brand, and timing. The relative ranking is much more stable, because a uniform price rise moves every food by the same percentage and leaves the order unchanged. Check the two or three items you buy most against your own receipts and re-run the numbers in the tool.

Why does the calorie figure matter if I am only comparing cost?

Because the cheapest protein per dollar is usually the most expensive protein per calorie, and calories are the constraint that actually limits how much of it you can use. Oats carry 23.0 calories per gram of protein against 5.0 for whey and 4.5 for canned tuna, so 30 g of protein from oats costs 690 calories while the same 30 g from whey costs 150. Multiply the calories per gram of protein by the grams you plan to take from that food to see the real cost of a swap.

Does the raw weight listed for meat and fish change the cost?

It changes how you should read it. Chicken breast, turkey breast, tilapia, and ground beef are listed raw, and cooking drives off water, so a cooked portion comes from a meaningfully larger raw purchase. If you plan meals in cooked grams, your true cost per gram of protein will be higher than the raw row suggests. Canned tuna in water is not raw, so it needs no such adjustment.

How much can one substitution actually save?

Swapping ground beef for chicken breast at a 150 g daily target saves $2.25 a day, which is $67.50 a month, and also removes 525 calories. Swapping tilapia for canned tuna saves $0.78 a day, or $23.40 a month. Moving 50 g of a chicken-based target to lentils saves $0.89 a day, about $26.70 a month, but adds 380 calories, so decide whether your day has room for those calories first.