Calcium
Of 19,820 on-market calcium products in the January 2026 DSLD dump, the median declared dose is 110 elemental mg, and 68.7% list unspecified/undisclosed form as the primary form.
Form share
Of 16,196 products with an identifiable primary form, here is the share held by each form of Calcium on the market today.
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| Form | Quality tier | n | Share |
|---|---|---|---|
| unspecified/undisclosed form | Unrated | 11,134 | 68.7% |
| Calcium Carbonate | Tier 2 | 2,391 | 14.8% |
| Dicalcium Phosphate | Unrated | 1,226 | 7.6% |
| Calcium Citrate | Tier 1 | 1,027 | 6.3% |
| Calcium Ascorbate | Unrated | 418 | 2.6% |
Form share over time
Entry-year breakdown of the top forms, 2012–2025.
Dose distribution
Deciles of declared dose per serving (elemental mg), among 18,617 products with a disclosed amount, against the RDA of 1000 and UL of 2500.
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- 42.8% of products fall below the fairy-dust threshold (100 mg, 20% of the studied low dose).
- 0.6% of products don't disclose an amount because Calcium is declared inside a proprietary blend.
Where does your dose rank?
Enter a per-serving dose (elemental mg) to see exactly how it compares to the 18,473 on-market calcium products with a disclosed amount. The chart above groups doses into deciles; this looks up the exact percentile for one number.
By dosage form
By target group
Top brands
| Brand | Products |
|---|---|
| Source Naturals | 384 |
| Douglas Laboratories | 326 |
| DC | 299 |
| Wonder Laboratories | 288 |
| Planetary Herbals | 226 |
| NutraBio | 216 |
| The Vitamin Shoppe | 213 |
| Cellucor | 193 |
| Syntrax | 190 |
| BulkSupplements.com | 186 |
| 21st Century | 182 |
| Bluebonnet | 177 |
| Nature Made | 163 |
| GNC AMP Advanced Muscle Performance | 159 |
| NOW | 157 |
| Centrum | 140 |
| Life Extension | 139 |
| Gaspari Nutrition | 132 |
| Puritan's Pride | 128 |
| Solgar | 127 |
| Country Life | 124 |
| GNC Pro Performance | 123 |
| Nature's Way | 120 |
| Core Nutritionals | 119 |
| Sunwarrior | 118 |
Search interest over time
How often people search for calcium on Google, US only, the last 5 years. This is public interest, not DSLD label data — a spike here doesn't necessarily line up with anything on this page, and Google's own index (100 = that term's peak popularity in the chosen window) is relative, not an absolute search-volume count.
Or see this search directly on trends.google.com.
Forms explained
Label discloses only "Calcium" with no salt form (largest single bucket, ~13,956 rows).
Elemental fraction: 40.0% (CaCO3, anhydrous (no commercial hydrate exists))
Absorption from calcium citrate was 20-27% higher than from carbonate in a meta-analysis (15 studies, 184 subjects; Sakhaee 1999), i.e. carbonate absorbed roughly 17-21% less; carbonate absorption is better with meals/gastric acid (general pharmacology, not from the abstract).
Source: Sakhaee K et al. 1999, Am J Ther 6(6):313-321, PMID 11329115
Elemental fraction: 21.1% (Ca3(C6H5O7)2 x 4H2O, tetrahydrate (USP-standard commercial form))
Meta-analysis of 15 studies (184 subjects): absorption significantly higher than carbonate by ~20-27% (27.2% fasting, 21.6% with meals). Citrate absorption is generally considered less dependent on gastric acid (general pharmacology, not from the abstract).
Source: Sakhaee K et al. 1999, PMID 11329115
Elemental fraction: 23.3% (CaHPO4 x 2H2O, dihydrate (label cross-check of 23% Ca/g matches dihydrate rather than anhydrous 29.5% -- spot-check against specific labels))
No specific human comparative bioavailability study vs carbonate/citrate was verified.
Source: none located (no human comparative absorption study of dicalcium phosphate vs carbonate/citrate found)
Elemental fraction: 9.4% (Ca(C6H7O6)2 x 2H2O, dihydrate (standard commercial form))
Used primarily as a buffered vitamin C source; no calcium-specific bioavailability study was found.
Source: none located (no calcium-specific bioavailability study found)
Reference values
- RDA (adult): 1000 elemental mg — 1000mg (men 19-70, women 19-50); 1200mg (women 51+, men 71+)
- Tolerable Upper Intake Level (adult): 2500 elemental mg — 2500mg (ages 19-50); 2000mg (ages 51+)
- Studied clinical dose range: 500–1000 mg
- Low end: Dawson-Hughes B et al. 1990, NEJM 323(13):878-883, PMID 2203964 -- 500mg/day elemental Ca (citrate malate vs carbonate) in postmenopausal women; citrate malate more effectively prevented bone loss in women with low baseline calcium intake. High end: Jackson RD et al. 2006 (WHI CaD trial), NEJM 354(7):669-683, PMID 16481635 -- 1000mg/day calcium carbonate + 400 IU D3 in 36,282 postmenopausal women; no significant ITT fracture reduction, adherent subgroup showed reduced hip fractures, increased kidney-stone risk.