Divide the bottle price by the number of labeled servings. Then check whether those servings are actually comparable.
The two calculations you need
First, divide the number of units in the bottle by the units in one labeled serving. That gives the number of labeled servings. Then divide the bottle price by that result to find cost per serving. Units can be capsules, tablets, gummies, or another consistent measure.
For a $24 bottle containing 120 capsules, a three-capsule serving gives 40 servings. $24 divided by 40 is $0.60 per serving. The same bottle costs $0.20 per capsule. These numbers answer different questions, so label them clearly.
Why the cheaper bottle may cost more per serving
Consider two hypothetical bottles: Bottle A costs $18 for 60 capsules with a two-capsule serving. Bottle B costs $24 for 120 capsules with a two-capsule serving. Bottle A contains 30 servings at $0.60 each; Bottle B contains 60 at $0.40 each.
That only makes Bottle B less expensive per labeled serving. It does not show that their ingredient amounts, formulations, testing, or suitability are equivalent. A cost comparison belongs alongside a label comparison, not in place of one.
Use the same price basis
Compare one-time purchases with one-time purchases. A subscription discount can change later, and the initial order may have a special promotion. Record whether you are using a regular price, a coupon, or a recurring offer.
Include delivery and tax when those costs are known. If a free-shipping threshold requires an extra purchase you do not need, the apparent saving can disappear. Use the actual checkout total in the calculator when you want a delivered-cost comparison.
Know what the calculation cannot tell you
A labeled serving is not automatically a daily dose, and a 30-serving bottle is not always a 30-day supply. Follow the exact directions and any advice from your clinician. Do not change the serving to chase a lower cost per milligram.
For powders or liquids, use the manufacturer’s stated servings per container when available. Scoop sizes, density, and measuring technique can make a simple unit-count calculation inappropriate. Our calculator lets you enter labeled servings directly for that reason.
Make it a repeatable shopping habit
Save the calculator in your browser bookmarks and use it when a price, bottle size, or subscription offer changes. Keep the exact formula and product version in view. If you compare products later, recheck the label instead of assuming the old numbers still apply.
A useful purchase decision balances suitability, transparent labeling, practical format, and cost. This tool does the arithmetic; it cannot decide whether a supplement is needed or choose a medically appropriate amount.
Sources & checks
Source pages checked October 4, 2026. General health information comes from the sources below. Product amounts and prices, where shown, come from manufacturer listings. See our methodology and correction policy.
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