The iron rule

The count is the trigger

Updated October 2026

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The arithmetic At an 18 mg dose At a smaller dose the picture changes Which is correct and looks inconsistent The concentration test can rescue you, or not The powder exception is worth knowing Recompute on every size extension Work it out on paper before you choose the bottle References

Work it through once and the threshold turns out to be easy to cross.

The arithmetic

Elemental iron per unit, multiplied by the number of units in the package. That is the whole calculation, and it is why a bottle-size decision is a compliance decision.

At an 18 mg dose

Fourteen units is 252 mg, which is over. Thirty is 540 mg. Sixty is 1,080 mg. One hundred and eighty is 3,240 mg, nearly thirteen times the threshold. There is no ordinary count that stays under.

At a smaller dose the picture changes

A 5 mg supporting dose reaches 250 mg at fifty units, so a 30-count bottle is under and a 60-count is over. That is exactly the case where a range has two different answers in it.

Which is correct and looks inconsistent

One size requiring child-resistant packaging and another not is the rule working as written. Treating the range as a single regulatory object is the mistake, and the instinct to make it consistent is the wrong instinct.

The concentration test can rescue you, or not

Both tests have to be met. A product with a very low iron concentration by weight can carry a large package total and still fall outside, so run both rather than stopping at the first.

The powder exception is worth knowing

Powdered preparations at no more than 0.12 percent weight-to-weight elemental iron are excepted. A powder and a capsule of the same formula are therefore not in the same position, which can inform the format choice.

Recompute on every size extension

A new count is a new package total. It feels like a packaging change rather than a formula change, which is precisely why the calculation does not get run.

Work it out on paper before you choose the bottle

Five minutes with a calculator tells you whether any of your intended counts sits near the threshold, and that is the moment the bottle decision is still free. After tooling and a case quantity it is not.

References

16 CFR 1700.14(a)(13), Dietary supplements containing iron, requiring special packaging where a supplement contains the equivalent of 250 mg or more of elemental iron from any source in a single package at 0.025 percent or more weight-to-volume for liquids or 0.05 percent or more weight-to-weight for nonliquids, excepting iron present solely as a colorant and powdered preparations at no more than 0.12 percent weight-to-weight. law.cornell.edu

Written from federal regulation and from measured catalog data, not from a packaging line. Whether a product crosses the iron threshold is a calculation about your formula and your fill count, and the figures here are the test rather than the answer. Nothing on these pages certifies a package as child-resistant; 16 CFR 1700.15 tests the assembly, not the cap.