What's in this review
This is a lookup page, not a plan. It gathers the everyday adult reference numbers, protein, fiber, water, sodium, and carbohydrate, into one place, with the source named for each. If you want the reasoning and the food sources behind any single one, the guides on protein, fiber, and calories go deeper.
One caveat sits above every number here, so read it first. These are general reference values for healthy adults, not medical or dietary advice for you personally. Real needs shift with age, sex, body size, activity, pregnancy and breastfeeding, and any medical condition. Use this page to understand the landscape and to spot a big gap, then take a personal target from a doctor or a registered dietitian nutritionist, not from a chart.
Where these numbers come from
Almost every value on this page is a Dietary Reference Intake set by the National Academies of Sciences, Engineering, and Medicine (formerly the Institute of Medicine). The DRIs use a few different reference types, and it helps to know what each means:
- RDA (Recommended Dietary Allowance): the intake that meets the needs of nearly all healthy people. Used here for protein and carbohydrate.
- AI (Adequate Intake): a reference value used when the evidence is not sufficient to set an RDA. Used here for fiber, total water, and the sodium adequacy figure.
- CDRR (Chronic Disease Risk Reduction intake): the level above which reducing intake is expected to lower chronic disease risk. Used here for sodium.
The everyday reference table
Values are for adults ages 19 and up unless noted. Where the figure differs by sex, both are shown.
| Nutrient | Reference value (adults) | Type | Source |
|---|---|---|---|
| Protein | 0.8 g per kg body weight per day (about 46 g women, 56 g men at reference weights) | RDA | NASEM DRI |
| Total fiber | about 25 g women, 38 g men (14 g per 1,000 kcal) | AI | NASEM DRI |
| Total water | about 2.7 L women, 3.7 L men (all beverages and food) | AI | NASEM DRI |
| Sodium (adequacy) | 1,500 mg per day | AI | NASEM DRI |
| Sodium (risk reduction) | 2,300 mg per day or less | CDRR | NASEM DRI |
| Carbohydrate | 130 g per day (minimum for glucose needs) | RDA | NASEM DRI |
Sources: the National Academies of Sciences, Engineering, and Medicine (NASEM, formerly the Institute of Medicine), Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids, and Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. You can look these up by title on the National Academies website to confirm the current figures.
Protein, in practice
The RDA of 0.8 grams per kilogram is per unit of body weight, so it scales with size. To turn it into a daily number, take your weight in pounds, divide by 2.2 to get kilograms, and multiply by 0.8.
| Body weight | Approx. protein RDA |
|---|---|
| 120 lb (about 54 kg) | about 44 g per day |
| 150 lb (about 68 kg) | about 54 g per day |
| 180 lb (about 82 kg) | about 65 g per day |
| 210 lb (about 95 kg) | about 76 g per day |
This is the amount that covers nearly all healthy adults, and it is a floor for general health, not a ceiling. Older adults, very active people, and those recovering from illness or surgery are often advised more, and the protein guide works through when and why. Run your own weight through the nutrition calculator for a quick figure.
Macronutrient ranges
Beyond the single-nutrient values, the National Academies also set Acceptable Macronutrient Distribution Ranges, the share of daily calories from each macronutrient linked to lower chronic disease risk in adults.
| Macronutrient | Share of daily calories (adults) |
|---|---|
| Carbohydrate | 45 to 65 percent |
| Fat | 20 to 35 percent |
| Protein | 10 to 35 percent |
Two further limits come from the federal Dietary Guidelines for Americans rather than the DRIs: keeping added sugars under 10 percent of daily calories and saturated fat under 10 percent of daily calories. Within any of these ranges, food quality still matters, so the source of the calories counts as much as the split. To see the carbohydrate row of that table converted into grams for your own calories, our review of how many carbs per day walks the 45 to 65 percent range through the arithmetic with a calculator alongside.
How to use this page
Compare your typical day against the table, and look for the large gaps rather than chasing a number to the gram. Most adults are low on fiber and high on sodium, so those two are the usual places a small change pays off. Increase fiber gradually with whole foods, watch sodium in packaged and restaurant meals, and treat protein as a floor to clear rather than a limit. Above all, remember the caveat at the top: these are general reference values, not a personal prescription, so bring any real target to a doctor or a registered dietitian who can weigh your full picture.
Frequently asked questions
How much protein do adults need per day?
The Recommended Dietary Allowance for protein is 0.8 grams per kilogram of body weight per day for adults, set by the National Academies. For a person weighing about 150 pounds, roughly 68 kilograms, that works out to about 54 grams per day. This is the amount that meets the needs of nearly all healthy adults, not a maximum, and athletes, older adults, and people recovering from illness may be advised more. This is general reference information, not personal advice, so talk with a doctor or registered dietitian about your own target.
How much fiber should I eat per day?
The Adequate Intake for total fiber is about 25 grams per day for adult women and about 38 grams per day for adult men, based on 14 grams per 1,000 calories, from the National Academies Dietary Reference Intakes. Most adults fall well short of this. Fiber comes from whole grains, beans, fruit, vegetables, nuts, and seeds. Increase it gradually and drink enough water so the change is comfortable, and check with a professional if you have a digestive condition.
How much water should I drink a day?
The Adequate Intake for total water is about 2.7 liters per day for women, roughly 11 cups, and about 3.7 liters for men, roughly 15 cups, from the National Academies. Importantly, this is total water from all beverages and food, and about 20 percent typically comes from food, so the amount you drink is less than the total. Needs rise with heat, exercise, pregnancy, and some medical conditions, so use thirst and urine color as everyday guides and ask a clinician about your situation.
What is the recommended sodium limit?
The National Academies set an Adequate Intake for sodium of 1,500 milligrams per day for adults, and a Chronic Disease Risk Reduction level of 2,300 milligrams per day, the point above which reducing intake is expected to lower chronic disease risk. Most people in the United States consume more than 2,300 milligrams, largely from packaged and restaurant food rather than the salt shaker. Anyone with high blood pressure or heart or kidney concerns should follow the specific target their clinician sets.
How many carbohydrates do adults need?
The Recommended Dietary Allowance for carbohydrate is 130 grams per day for adults, the amount set to supply the brain with glucose, from the National Academies. That is a minimum for basic function, not a target for total intake, which is usually much higher and depends on your calories and activity. The Acceptable Macronutrient Distribution Range suggests 45 to 65 percent of calories from carbohydrate for adults. Quality matters as much as quantity, so favor whole grains, fruit, vegetables, and legumes over refined sources.
Are these numbers the same for everyone?
No. These are general reference values for healthy adults, and real needs vary with age, sex, body size, activity, pregnancy or breastfeeding, and medical conditions. The Dietary Reference Intakes themselves list different values across life stages. They are a useful starting point and a way to spot large gaps in a diet, but they are not a personal prescription. For a target matched to you, consult a doctor or a registered dietitian nutritionist.