21st Century Calcium Citrate Plus D3 Maximum
- Calcium
- Tablet
- Calcium
- 400
- Better rated than 63%
- More reviewed than 77%
A straightforward calcium citrate plus D3 tablet built as a direct alternative to Citracal +D3, with a 400-count bottle for long-term use.
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How it ranks among the 107 calcium we track
4.7★ across 5,700 Amazon ratings, Bayesian-smoothed toward the category average.
5,700 Amazon ratings, weighted on a log scale so huge counts don't drown everything.
2,000+ bought on Amazon last month.
Brand identity, imagery, description and spec coverage.
The ProductDome score is separate from the Amazon rating shown above: it combines the Bayesian-smoothed Amazon rating with evidence volume, tracked demand, and data quality across the 107 calcium we track - how the scorecard works · full calcium data report. Confidence: high - strong rating volume and complete data.Last refreshed Aug 4, 2026. Data-computed, not a hands-on test. Compiled by the ProductDome Research Team.
Overview
21st Century's Calcium Citrate Plus D3 Maximum delivers 630 mg of calcium per serving in citrate form, positioned as a gluten free, non-GMO alternative to Citracal +D3. Each bottle holds 400 tablets, a supply built for daily long-term use.
Calcium citrate is the form the label leans on, and the product is marketed explicitly as a swap for a well known brand name rather than a novel formula. With 400 tablets in one bottle, the count matters as much as the dose for anyone comparing cost per serving.
- 630 mg calcium per serving
- Calcium citrate form
- 400 tablets per bottle
- Gluten free, non-GMO
Who it's for
Suits shoppers already taking a calcium plus D3 tablet who want a gluten free, non-GMO version at a lower price than the brand it's compared against. Not aimed at anyone needing a liquid, gummy, or once-a-day mega-dose format.
Strengths and trade-offs
Drawn from this product's published specifications.
- 630 mg calcium citrate per serving
- 400-tablet bottle for extended use
- Gluten free and non-GMO
- Tablet form only, no gummy or liquid option
- Flavor and dosing schedule not detailed
Performance notes
Calcium citrate is the form used here rather than calcium carbonate, which the brand frames as easily absorbable. The 630 mg per serving figure and the tablet form are the two facts the label leads with; the rest of the dosing schedule is not specified in the listing.
Specifications
| Brand | 21st |
|---|---|
| Model | 27495 |
| Form | Tablet |
| Supplement Type | Calcium |
| Count | 400 |
| Benefits | Bone Strength |
| Flavor | Unflavored |
| Diet | Gluten Free |
| Allergens | Gluten Free |
Other 21st calcium
How it compares
This product against the closest alternatives we track in calcium.
| Product | Amazon rating | Ratings | ProductDome score |
|---|---|---|---|
| 21st Century Calcium Citrate Plus D3 MaximumThis product | 4.7 / 5 | 5,700 | 4.6 / 5 |
| Nature Made Calcium Magnesium Zinc with Vitamin D3NATURE | 4.8 / 5 | 19,900 | 4.7 / 5 |
| Nature's Bounty Calcium Magnesium & Zinc CapletsNature's | 4.7 / 5 | 23,000 | 4.6 / 5 |
| Caltrate 600 Plus D3 Calcium and Vitamin D Supplement TabletsCaltrate | 4.7 / 5 | 16,400 | 4.6 / 5 |
| Citracal Slow Release- Calcium 1200 mg with Vitamin D3Citracal | 4.7 / 5 | 11,909 | 4.6 / 5 |
Similar calcium from other brands
Questions about the 21st 27495
Common buyer questions answered straight from the product spec data - no fluff, no "it depends".
What form of calcium is in 21st Century Calcium Citrate Plus D3 Maximum?
It uses calcium citrate, delivering 630 mg of calcium per serving alongside vitamin D3, in tablet form.
How many tablets come in the bottle?
The bottle contains 400 tablets.
Is this product gluten free?
Yes, it's labeled gluten free and non-GMO.