Vitamin Cost Per Day Calculator: Daily Cost From a Bottle Price
Work out the per-day cost of a vitamin or supplement from the bottle price and how long it lasts — the right way to compare brands and pack sizes, since bottle price alone hides differences in serving count and dose.
Adjust the inputs and select Calculate for a full breakdown.
Compare Common Scenarios
How the numbers shift across typical situations for this calculator:
| Scenario | Cost per day |
|---|---|
| $18 · 60 days ($0.30) | $0.30 |
| $30 · 30 days (two/day dose) | $1.00 |
| $25 · 90 days (bulk) | $0.28 |
| $45 · 60 days (premium) | $0.75 |
How This Calculator Works
Enter the bottle price and the number of days it lasts at the labeled daily dose. The calculator divides one by the other for the cost per day. Watch the serving size — a bottle with 60 capsules at two-per-day lasts only 30 days, doubling its cost per day versus a one-per-day product.
The Formula
Cost per Unit
Total Amount is the full cost or price, Quantity is the number of units it covers
Worked Example
An $18 bottle lasting 60 days is $0.30 a day. That sounds trivial, but supplements stack: a daily routine of several supplements at $0.30–$1.00 each can run $30–$100+ a month, or hundreds to over a thousand dollars a year. Comparing cost per day — not bottle price — is essential, because a 'cheaper' bottle may contain fewer servings or require a higher daily dose, making it more expensive per day.
Key Insight
Cost per day is the honest unit for supplements because bottle prices are deliberately hard to compare: serving counts, doses-per-day, and concentrations vary widely, so the cheapest bottle is often not the cheapest per day. Two practical points. First, check the serving size on the label — a bottle of '60 capsules' at two capsules per day is a 30-day supply, so its real cost per day is double what the bottle price suggests. Second, the bigger question this calculator can't answer is whether you need the supplement at all: many supplements have limited evidence of benefit for people without a deficiency, and the supplement industry is lightly regulated for efficacy. The most cost-effective move is often to confirm an actual need (ideally via a doctor or bloodwork) before spending, then use cost per day to choose the cheapest quality product for the supplements you genuinely benefit from. Bulk and subscribe-and-save usually lower the per-day cost, and store/generic versions of the same dose are frequently far cheaper than branded equivalents.
Frequently Asked Questions
How is vitamin cost per day calculated?
Divide the bottle price by the number of days it lasts at the labeled daily dose. An $18 bottle lasting 60 days is $0.30 a day. Always base 'days it lasts' on the actual dose, not just the capsule count.
Why does serving size matter?
Because it changes how long the bottle lasts. A bottle of 60 capsules at two per day is only a 30-day supply, so its cost per day is double a one-per-day product. Check the label's serving size before comparing — capsule count alone is misleading.
How can I lower my supplement cost per day?
Buy in bulk or via subscribe-and-save (usually cheapest per day), choose store/generic versions of the same dose (often far cheaper than branded), and avoid paying for proprietary blends or high doses you don't need. Cost per day makes these comparisons clear across brands and sizes.
Are expensive supplements better?
Not necessarily. For most common vitamins, a quality generic at the same dose performs the same as a premium brand at a fraction of the cost per day. Pay for third-party testing/quality where it matters, but a higher price doesn't reliably mean better efficacy.
Should I be taking the supplement at all?
That's the bigger question this calculator can't answer. Many supplements show limited benefit for people without a deficiency, and the industry is lightly regulated for efficacy. Confirm an actual need (ideally via a doctor or bloodwork) before spending — the cheapest supplement is the one you don't need to buy.
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Methodology & Review
The cost per day is the bottle price divided by the number of days it lasts (servings at the labeled dose). It counts the supplement only and does not judge efficacy, quality, or whether the supplement is needed.
Written by Ugo Candido · Last updated May 22, 2026.