Compare calcium supplements on the amount of calcium in each daily dose, the form (carbonate, citrate and others), what else is added, such as vitamin D, magnesium or K2, and the cost per day. The NHS says most adults can get the 700mg of calcium they need from food, so it's worth checking your diet before you add a supplement.
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How much calcium do you need a day?
The NHS says adults aged 19 to 64 and over need 700mg of calcium a day, and that you should be able to get this from your daily diet. Good sources include milk, cheese, calcium-fortified soya drinks, curly kale and fish where you eat the bones, such as sardines.
Needs change with age. The British Dietetic Association lists higher amounts for some groups: 800mg a day for girls and 1,000mg for boys aged 11 to 18, 1,250mg for breastfeeding mothers, and 1,200mg for post-menopausal women and men over 55. If you're not sure whether your diet covers it, start there before buying a supplement.
What does calcium do?
Calcium is needed for the maintenance of normal bones and teeth. That is the exact wording of two claims authorised in the GB register of nutrition and health claims, and it can only be used for a food that is at least a source of calcium.
Calcium also contributes to normal muscle function and normal blood clotting. We use only these authorised statements, and we don't say any product in this collection will change how strong your bones are.
What does %NRV mean on a calcium label?
%NRV shows how much of the Nutrient Reference Value one serving provides, and the NRV for calcium is 800mg. So a tablet with 400mg of calcium shows as 50% NRV, and 800mg shows as 100%.
The NRV is a labelling reference, not a personal target. Our guide to reading a supplement label explains it in more detail.
Calcium carbonate or calcium citrate?
Both are common forms, and the main practical difference is when you take them. The US National Institutes of Health says calcium carbonate is absorbed best when taken with food, while calcium citrate is absorbed well with or without food.
This collection includes calcium carbonate, calcium citrate (tablets and powder), calcium lactate, coral calcium and seaweed-derived calcium. Whatever the form, compare the amount of calcium itself per daily dose, which the label should list.
| What you'll see | What it means | What to check |
|---|---|---|
| Calcium carbonate | A common, compact form | Directions say to take it with food |
| Calcium citrate | Can be taken with or without food | Often more tablets for the same calcium |
| Cal-Mag or Cal-Mag-Zinc | Calcium combined with magnesium (and zinc) | The amount of each mineral per dose |
| Calcium with D3 and K2 | Calcium plus vitamins D and K | Vitamin D you already get elsewhere |
Some products here, such as calcium D-glucarate and calcium ascorbate (a form of vitamin C), are listed because calcium is in the name. They are not mainly calcium supplements, so read the label.
Should you take calcium with vitamin D?
Many people do, and the authorised claim is that vitamin D "contributes to normal absorption/utilisation of calcium and phosphorus" (wording from the authorised claims list). The British Dietetic Association says vitamin D helps your body to absorb and use calcium from the foods you eat.
Separately, the NHS advises adults to consider a daily supplement containing 10 micrograms of vitamin D, especially in autumn and winter. If you also take a vitamin D supplement or a multivitamin, add up the vitamin D across everything you take.
How to compare calcium supplements on value
Work out the cost per 500mg of calcium, because tablet sizes vary a lot. A tablet that looks cheap may contain much less calcium than another.
How to compare value (example figures, not real products): a £8 tub of 120 tablets with 300mg of calcium each holds 36,000mg in total, which is 72 lots of 500mg, so about 11p per 500mg. A £12 tub of 90 capsules with 200mg each holds 18,000mg, or 36 lots of 500mg, which is about 33p per 500mg: three times the cost for the same calcium.
"Two products that look almost identical on the shelf can offer different value," says Andy Arshad, who runs SupplementHQ.
Can you take too much calcium?
Yes. The NHS says taking high doses of calcium (more than 1,500mg a day) could lead to stomach pain and diarrhoea, and that 1,500mg or less a day is unlikely to cause any harm.
Remember to count calcium from food as well as every supplement you take. The NIH notes that calcium supplements can interact with certain medicines, including some antibiotics and thyroid medication, so speak to your GP or pharmacist before taking calcium if you take medication, have a medical condition, or are pregnant or breastfeeding.
Which is the best calcium supplement?
The best one for you fills the gap your diet leaves, in a form you can take as directed, at a sensible cost per day. A higher dose doesn't automatically mean a better product.
"We want customers to understand what they're taking rather than simply choosing the highest numbers on the label," says Andy. If you're unsure what you need at all, read our guide to what supplements you actually need, or go back to all vitamins and supplements.
We sell the products on this page. That's our commercial interest, and it's why we show the evidence alongside them. This page is general information for adults, not personalised medical advice. Food supplements should not replace a varied, balanced diet.
Written by Andy Arshad, SupplementHQ. Last reviewed 11 October 2026.