Buying calcium: elemental mg, not mg of salt
Futures Nutrition Editorial Team · 13 August 2026
Buying calcium: elemental mg, not mg of salt
The short answer: four lines decide the purchase — how much elemental calcium is in the daily serving, how many tablets that daily serving consists of, which compound is behind it, and what 1,000 mg of calcium costs in that particular pack. The big number on the front is not one of them: "1,250 mg calcium carbonate" is 500 mg of calcium, and only the second figure appears in the nutrition table on the back.
With calcium there is one further question that does not arise with most other minerals: whether a pack is needed at all. Calcium is the one mineral where a single meal — two slices of hard cheese — already covers half the daily requirement. Which is why buying advice here does not begin at the shelf, but at the fridge.
Work out the gap first, then choose the pack
The German Nutrition Society (DGE) gives 1,000 mg of calcium a day for adults. In the German National Nutrition Survey II the median was 1,052 mg for men and 964 mg for women — roughly at the level of the recommendation, while just under half of men and a good half of women did not reach it. So the gap is usually small, and differently sized for everyone; anyone eating cheese or yoghurt daily, or drinking a calcium-rich mineral water, often has no gap at all.
How small it tends to be is shown by the same survey in those who actually did supplement: a median of 146 mg (men) and 200 mg (women) a day. That is the order of magnitude the purchase is about — not the whole daily amount.
The German Federal Institute for Risk Assessment (BfR) therefore proposes a maximum of 500 mg of calcium per daily serving for food supplements, and recommends that from 250 mg per daily intake the pack carry a note advising against further calcium-containing products. A product with an 800 or 1,000 mg daily serving is therefore not a "stronger" product in Germany, but one that sits above what the authority envisaged for freely available supplementation. How large your own gap is depends on what is already on the plate.
The number that counts: elemental calcium per daily serving
What has to appear on the pack is regulated. Under § 4 of the German Food Supplements Ordinance, the amount of the nutrient in relation to the recommended daily intake and the percentage of the nutrient reference value must be stated. The reference value for calcium is set out in Annex XIII of Regulation (EU) No 1169/2011 and is 800 mg. From this follows a conversion you can do in your head in the shop:
| Figure on the pack | Calcium per daily serving |
|---|---|
| 15 % NRV | 120 mg |
| 25 % NRV | 200 mg |
| 50 % NRV | 400 mg |
| 62.5 % NRV | 500 mg |
| 100 % NRV | 800 mg |
The first row has a secondary meaning that helps with comparisons. 15 % of the reference value is the threshold above which a product counts as a source of calcium at all — and only then may the authorised statement be used: Calcium is needed for the maintenance of normal bones and teeth. If that sentence appears on a pack, the daily serving therefore contains at least 120 mg. Conversely, the sentence says nothing about quality: it is permitted from 120 mg and remains the same at 500 mg.
The amount of the salt, by contrast, is not a mandatory item in the nutrition section — when it appears on the front, it is advertising. 1,250 mg of calcium carbonate is 500 mg of calcium; 1,000 mg of calcium citrate is around 210 mg of calcium. Anyone comparing those two packs by the front number takes the weaker one for the stronger.
How many tablets make up the daily serving?
The second line is the one most often overlooked, yet it determines how long the pack lasts and what it costs. "120 tablets" means four months at one tablet a day and forty days at three.
It also determines tablet size, and with calcium that is no side issue. For 500 mg of calcium you need at least 1.25 g of calcium carbonate — plus pressing aids, coating and whatever else is in the product. Tablets like that are large. With the low-percentage salts it quickly becomes impossible: 500 mg of calcium from gluconate would be over 5 g of salt, which no tablet can hold any more. Manufacturers solve this in three ways — they split the daily serving across several tablets, they move to effervescent or chewable tablets, or they lower the serving. Anyone who swallows tablets badly should look specifically for a score line or an effervescent form; whether and how the daily amount can be divided is set out in Taking calcium: dose per serving and spacing.
Price: first per day, then per 1,000 mg
Two figures answer two different questions, and both are useful. The price per day says what the habit costs. The price per 1,000 mg of calcium says what the mineral costs — and is what makes packs with different serving sizes comparable in the first place. A worked example with three invented but realistic packs:
| Pack | Serving | Price | Lasts | Price per day | Price per 1,000 mg Ca |
|---|---|---|---|---|---|
| A: 60 tablets, 2 a day | 500 mg | €9.90 | 30 days | €0.33 | €0.66 |
| B: 120 tablets, 1 a day | 200 mg | €14.90 | 120 days | €0.12 | €0.62 |
| C: 100 tablets, 1 a day | 400 mg | €12.00 | 100 days | €0.12 | €0.30 |
Packs A and B cost almost the same per 1,000 mg, but in everyday use the factor is nearly three — because A delivers three times the amount. C is by far the cheapest per milligram. Whether C is therefore the right choice depends solely on whether your own gap really is 400 mg. A product that delivers more than needed is not cheaper, only larger.
The compound: a buying decision in only two cases
Which calcium compounds may be used at all is listed exhaustively in Annex II of Directive 2002/46/EC; the list is closed. Within that list, the choice is secondary for most buyers: taken with food, carbonate and citrate are absorbed practically equally well, as Heaney and colleagues measured twice, in 1999 and 2001.
Two cases remain in which the compound really does count:
- Little or no stomach acid — for instance while taking acid-suppressing medicines or after stomach surgery. Carbonate needs acid to dissolve; citrate does not.
- Taking it on an empty stomach. Anyone taking the tablet in the morning without breakfast is on safer ground with citrate.
For everyone else: carbonate with food, and that is that. The figures are set out in Calcium forms: carbonate, citrate, gluconate.
What comes along in a combination product
Calcium rarely stands alone. Vitamin D3 in the same product has a factual reason — Vitamin D contributes to normal absorption and utilisation of calcium. Vitamin K2 is often added alongside; what is authorised there and what is not is set out in Vitamin K2 and calcium.
With a combination product a second calculation is worth doing: anyone already taking a D3 product is adding two labels together. And anyone supplementing magnesium is better off buying the combination separately — then one amount can be changed without changing the other.
Our Calcium + Vitamin D3 4,000 IU provides 200 mg of calcium per tablet — 25 % of the nutrient reference value — and 100 µg of vitamin D3, at one tablet a day. That is deliberately the small serving: it stays below the 250 mg notice threshold, leaves room for whatever is on the plate anyway, and keeps the tablet swallowable. At €14.90 the tub lasts 120 days, so around 12 cents a day.
How calcium sits alongside magnesium, zinc and iron is shown by the overview in the Minerals category; all calcium products are in the Calcium category.
The shelf comparison in five steps
- Estimate your own gap — what does your diet deliver on a normal day?
- Read the calcium per daily serving in the nutrition table, not the amount of salt on the front.
- Check the tablets per daily serving — that tells you how long the pack lasts.
- Form the price per day and per 1,000 mg of calcium, and only then compare.
- Check the compound — but only with acid blockers, fasting intake or difficulty swallowing.
Frequently asked questions
Is a more expensive calcium product better? Not as such. With calcium, the price follows above all the serving size, the dosage form and the additives. A rarer salt on the pack justifies no premium: in 2001 Heaney and colleagues concluded, in a study expressly designed as a cost-benefit comparison, that with equal absorption the cheaper carbonate is the more economical choice.
Do I need vitamin D in the same product? Only if there is not already a D3 product in the cupboard. Vitamin D contributes to normal absorption and utilisation of calcium — so the reason for the combination is real. Two products containing vitamin D side by side are nevertheless a doubling that nobody planned.
What should I make of calcium from Sango sea coral, oyster shells or eggshells? Chemically that is, as a rule, calcium carbonate, with the same properties: around 40 % calcium, acid-dependent dissolution. The statement of origin on the pack changes nothing about that and justifies no higher price per milligram. What counts remains the declared amount of calcium.
Is the large pack worth it? Usually yes, but not because of the unit price alone. Check first whether the daily serving matches your own gap, and then the best-before date: a year's pack of which half is left after eight months was not cheaper. How much may add up in total depends on the upper limit for calcium as a whole, not on this one pack.
Food supplements are not a substitute for a balanced and varied diet and a healthy lifestyle.
Sources: Regulation (EU) No 1169/2011, Annex XIII (nutrient reference value for calcium 800 mg; significant amount = 15 %) · Regulation (EU) No 432/2012 in conjunction with Regulation (EC) No 1924/2006, Annex (authorised claim for calcium; condition "source of") · Directive 2002/46/EC, Annex II (permitted mineral sources) and Article 8 (declaration per recommended daily serving) · German Food Supplements Ordinance (NemV) § 4 · German Federal Institute for Risk Assessment, proposed maximum levels for calcium in foods including food supplements, 2021 · German Nutrition Society, reference values for calcium intake · Max Rubner Institute, German National Nutrition Survey II, results report part 2 (2008) (medians 1,052 and 964 mg/day; supplementation median 146 and 200 mg/day) · Heaney RP, Dowell MS, Barger-Lux MJ, "Absorption of calcium as the carbonate and citrate salts", Osteoporos Int 1999;9(1):19–23 (PMID 10367025) · Heaney RP et al., "Absorbability and cost effectiveness in calcium supplementation", J Am Coll Nutr 2001;20(3):239–246 (PMID 11444420) · Elemental proportions calculated from the molar masses of the respective compounds; price examples are worked examples.
