How much calcium do you need per day?

The RDA for calcium is 1,000 mg a day for adults 19–50 and men 51–70, and 1,200 mg for women 51+ and all adults 71+.

These are the reference amounts used on US food labels and in dietary guidance, not personal targets. What you need shifts with age, pregnancy, medication and health conditions. The % Daily Value shown on every food page here is calculated against the FDA Daily Value for calcium, which is 1300 mg a day.

What this means for you

A thousand milligrams a day for most adults, and 1,200 for women past fifty and everyone past seventy. Calcium is one of the few nutrients that is genuinely hard to reach without either dairy or a plan, and the arithmetic explains why. A glass of whole milk is 306 mg. A small pot of plain Greek yogurt is about 173 mg. Three or four dairy servings a day and you are there.

Take dairy out and you have about a thousand milligrams to replace from foods that carry it in smaller amounts. That is doable, but it does not happen by accident.

Before you start counting, look at where calcium already reaches you. In American survey data milk and dairy supplied about 37 per cent of the total, and another 17 per cent arrived inside mixed dishes: the pizza, the sandwiches, the pasta. Grains added 12 per cent, over half of that from bread, rolls and tortillas. Most people are getting a good deal of their calcium from food they would never write down as a calcium food.

What works without dairy

Calcium-set tofu is the quiet winner, at 253 mg in half a cup. Tinned fish eaten with the bones is excellent, and a cup of drained sardines is 569 mg. Almonds, fortified plant drinks, kale and broccoli all contribute.

Plant milk deserves its own paragraph, because it is a lottery you can win by reading. An audit of 129 plant milks on sale in one supermarket region found 80.6 per cent of them fortified with calcium, and as a group they matched cow's milk for it while falling well short on protein, iodine and B12. The remaining fifth of cartons had no calcium added, and an unfortified almond or rice drink carries almost none of its own. The share being fortified has also moved fast, from 42.6 per cent in 2020 to around 80 per cent within four years, so a brand you checked two years ago is not the brand you are buying now. Turn the carton around and read the panel.

Spinach is the trap. It looks like a calcium food and it is not, because oxalic acid in the leaf binds the calcium before you can absorb it. About 5 per cent of the calcium in spinach reaches you, against about 27 per cent from milk. Kale and broccoli are low in oxalate and their calcium is available, so the answer is not to give up greens. It is to know which green you are eating.

Established. If you take a supplement, dose size matters more than the total. Absorption is best at 500 mg or less at a time. The body takes up about 36 per cent of a 300 mg dose and 28 per cent of a 1,000 mg one. Two small doses at different times of day deliver more calcium than one big one, out of the same box.

Unsettled. Calcium supplements and heart risk is one of the few places where two credible expert bodies read the same evidence and disagreed. A pooled analysis of 14 randomised trials in almost 29,000 healthy postmenopausal women found a 15 per cent higher risk of cardiovascular disease. An expert panel from the National Osteoporosis Foundation and the American Society for Preventive Cardiology concluded, on moderate-quality evidence, that calcium changes that risk neither way. Both are serious readings of a messy literature, and the honest position is that this is not settled. Nothing in the dispute touches calcium from food.

What supplements have actually been shown to do

Less than the shelf suggests. The largest review so far pooled 69 trials and 153,902 people and found little to no effect of calcium supplements on the risk of breaking a bone. Calcium on its own landed at a risk ratio of 0.91 with an interval that still crosses 1. Calcium with vitamin D landed at 0.91 as well, this time with high certainty, which is a real effect and a small one.

Who was in those trials matters. Most of them recruited people living at home, and 73 per cent recruited people who were not at high risk of fractures or falls, and the reviewers say the evidence for people who are frail or in residential care is thin. So this answers a question about buying a tub off a shelf. It does not answer a question about treatment somebody prescribed you.

Myth. Calcium is sold for blood pressure too. In people whose pressure is normal, supplements lower the top number by 1.37 mmHg and the bottom by 1.45, and doses under 1,000 mg a day did nothing measurable at all. Real, and far too small to take a tablet for.

If you are pregnant, this advice has changed

Established. Calcium in pregnancy makes little to no difference to pre-eclampsia. The 2025 Cochrane update puts the risk ratio at 0.92 once the small trials are set aside, and rates that null result high certainty. Starting before conception does not help either, including in women whose last pregnancy had pre-eclampsia.

How that reversed is worth a minute, because this sort of thing usually happens out of sight. The reviewers did not find new trials pointing the other way. They took out 20 trials they had counted before, 11 because the entry rules changed and 9 over doubts about whether the data were real. What was left showed nothing. An effect that vanishes when the doubtful studies leave the pile was telling you about the studies rather than about calcium.

If you were told to take calcium in pregnancy, do not simply stop. Take this page to whoever is looking after you and ask what it was for, because there are other reasons to prescribe calcium and we cannot see yours from here.

Myth. Protein and grains do not leach calcium out of your bones. The alkaline diet story rests on one real observation, that eating more protein puts more calcium in the urine. Pooling the controlled balance studies where acid load was deliberately changed, urinary calcium tracked that load closely and had no relationship at all with whole-body calcium balance or with a marker of bone breakdown. More calcium in the urine turned out to say nothing about calcium leaving the body.

One more number is worth having before you decide about a tablet. About a quarter of Americans took a calcium-containing supplement on a given day, and among those who did it averaged 521 mg on top of what they ate, with women and people over 60 taking more. Half the daily requirement arriving in one lump is not a rounding error, which is why what supplements do and do not do is worth the space above.

So the plan is the boring one. Build the number from meals where you can. Treat supplements as a way to close a gap you have actually measured, not as insurance. And if you already take them, splitting the dose costs nothing and works better.

There is one more piece of the picture worth adding, and it is the reason the advice above puts food first. Across 35 prospective cohorts with 163,657 deaths, calcium from food tracked with slightly lower mortality, while calcium from supplements tracked with nothing at all. Cohorts cannot prove cause, so read that as an absence of a harm signal from food rather than as a benefit. The trials that worried people all tested tablets, usually 1,000 mg at once. We read those trials against each other here.

Two footnotes to the number above. What it protects against is bone loss: long-term shortage reduces bone strength and leads to osteoporosis, without any symptom along the way. And if you take a supplement, keep it a few hours away from quinolone antibiotics such as ciprofloxacin, which absorb less well when calcium arrives at the same time.

Written from the evidence cards and the data on this page, then checked back against the sources. Bioma Learn has no human medical reviewer at this time and we say so rather than invent one. Information, not medical advice. How we verify.

Foods highest in calcium on this site

• Sesame seeds, whole, dried — 1404 mg per 1 cup (108% DV)
• Parmesan cheese, dry grated, reduced fat — 1109 mg per 1 cup (85% DV)
• Mozzarella cheese, nonfat — 1085.9 mg per 1 cup, shredded (84% DV)
• Monterey cheese — 984.7 mg per 1 cup, diced (76% DV)
• Mozzarella cheese, low sodium — 964.9 mg per 1 cup, diced (74% DV)

All calcium sources ranked →

Full guide: Calcium: the supplement question that experts still disagree about