Supplement Cost Calculator

Four example supplements (multivitamin, fish oil, vitamin D3, probiotic) cost $41.55 a month and $498.60 a year

A bottle's price tells you little until you divide it by how long the bottle lasts. A 100-tablet multivitamin at $14.99 costs about $0.15 a day at one tablet. A 30-capsule probiotic at $24.99 costs $0.83 a day at one capsule. The two bottles are only $10 apart on the shelf, yet the probiotic runs $25.34 a month against $4.56 for the multivitamin. Add up all four examples in the calculator above and you get $1.36 a day, $41.55 a month and $498.60 a year.

The calculator answers two questions. My supplements takes everything you currently take and shows the monthly and yearly cost, each product's share, and when you will need a new bottle over the next 12 months. Compare products lines up candidates for the same ingredient and ranks them. Enter the amount per capsule (or tablet) and the ranking is no longer about which bottle costs less per month, but which one gives you the same amount of the ingredient for less money.

Why work it out as a monthly cost

• The bottle price hides what you actually spend. Bottles hold different amounts and are used at different rates, so an expensive bottle can last for months while a cheap one is gone in a few weeks. In the examples, the probiotic bottle costs $10 more than the multivitamin but costs more than five times as much per month.
• Several bottles mean several restock dates. A 30-day probiotic, a 60-day fish oil, a 100-day multivitamin and a 180-day vitamin D3 run out at different times, so purchases bunch up in some months. The new-bottle calendar lays each bottle end to end and shows how many you buy in 12 months and what they cost.
• You may be buying the same ingredient twice. The NIH Office of Dietary Supplements puts it this way: "Taking more than you need costs more and might also raise your risk of side effects." It also notes that "Manufacturers may add vitamins, minerals, and other supplement ingredients to foods you eat, especially breakfast cereals and beverages. As a result, you may get more of these ingredients than you think, and more might not be better." Seeing your whole list next to its cost is a practical first step toward spotting overlap.
• Value is a price per amount. If one capsule holds more of the ingredient, the product with the lowest monthly cost may simply contain less. Compare products mode ranks them by price per 1,000 mg (or per 1,000 IU, 100 mcg, 10 billion CFU) to expose that difference.

How to use it

1. Pick a view. Choose "My supplements" to see what your current routine costs, or "Compare products" if you are choosing what to buy.
2. Enter the price and the amount in the container on each card. Use what you actually paid; if you include coupons or shipping, do it the same way for every product. The amount in the container is the total number of tablets, capsules, packets, pieces, mL or g. For a 3-bottle pack, enter the pack price and the combined count.
3. Enter how you take it. Read the serving size on the Supplement Facts panel: "Take 2 capsules once a day" means a serving of 2 and 1 time a day. If you skip weekends, choose "5 days/wk"; if you take it every other day, choose "Alt. days".
4. In My supplements mode, check the day you open a new bottle. It starts as today. If you are partway through a bottle, change it to the day you opened it so the next-bottle dates come out right.
5. In Compare products mode, enter the amount per capsule (or tablet). For fish oil, use the EPA and DHA amounts added together, not the weight of the whole softgel. Use the same unit for every product so they can be ranked by price per amount.
6. Keep the result. "Copy results" gives plain text, "Save as Excel" gives a table with one row per product, and "Copy link" gives an address that reopens the current list. Turn on "Save in this browser" and your list is still there next time.

How the numbers are calculated

Everything starts from the amount you take per day. If you do not take it daily, the calculator averages the week by dividing the weekly amount by 7. A month is one twelfth of a 365-day year, about 30.4 days, so twelve months always add up to the yearly cost.

Amounts on screen are rounded to the cent. A price per unit under $1, such as the $0.167 above, is shown to the third decimal. The total adds up the rounded amount for each product, so the product amounts always sum to the total exactly. When the days per bottle is not a whole number (100 tablets at 3 a day is 33.3 days), the leftover carries into the next bottle, and the new-bottle day is the first day you cannot cover a full day's amount.

The reference amount depends on the unit: 1,000 mg for mg, 100 mcg for mcg, 1,000 IU for IU, 10 g for g, and 10 billion CFU for probiotics. If two labels list the same ingredient in IU and in mcg, convert one before comparing.

Four examples: monthly cost, yearly cost and new-bottle dates

These are the same values the calculator shows on first load, with the first bottle opened on October 18, 2026. The prices are examples meant to show how the calculation works, so replace them with what you actually paid.

The probiotic takes the biggest share of the monthly cost, 61%, and it is also the first to run out: you need its second bottle on November 17, 2026. Over the 12 months you open 27 bottles, counting the one opened on day one, and the bottle prices add up to $551.73. That is $53.13 more than the averaged yearly cost of $498.60, because the last bottle of each product is opened before the 12 months end and is still partly full. Use the bottle total when you plan what to buy, and the average yearly cost when you compare one year with another.

Compare value by price per amount

Two fish oils can have very different amounts of EPA and DHA in each capsule. The three products below appear when you choose "Compare products" and press Example. Each is taken as directed on the label.

On monthly cost alone, A is cheapest at $5.40, but it delivers only 600 mg a day. Per 1,000 mg, C is cheapest at $0.278; A ($0.296) costs 6% more than C and B ($0.463) costs 67% more. If you wanted at least 1,000 mg a day from A, you would take two capsules (1,200 mg), and the monthly cost would rise to $10.81, more than C at $8.45. Without lining up the amounts, the "cheap" product can simply be the one with less in it.

Price per amount only means something between products with the same ingredient. A dollar figure per 1,000 mg of magnesium and one per 1,000 mg of vitamin C cannot be ranked against each other. The figure also ignores differences in absorption, the form of the ingredient, and everything else on the label.

How the schedule changes the cost

This table uses one product, 60 capsules for $18.00 ($0.30 a capsule), and changes only how it is taken. The same bottle is gone in 20 days at three a day and lasts four months when taken every other day.

Five days a week, every other day and three days a week are averaged over a seven-day week. Depending on which days you actually take it, the real new-bottle date can differ by a day or two.

Where to look first to spend less

1. Check for overlap. If your multivitamin already lists an ingredient you also buy on its own, such as vitamin D, you pay twice and take more than you may have planned. Compare the Supplement Facts panels side by side.
2. Look at price per unit and days per bottle together. A large bottle may have a lower price per unit, but if you will not finish it before the expiration date, the leftover is wasted money. Compare the "supply" figure on each card with the date printed on the bottle.
3. Choose between candidates by price per amount. Check whether the product with the lowest monthly cost also contains less per day, then decide.
4. Enter discounts, subscriptions and bundles the same way for every product. If one product is entered at a coupon price and another at full price, the ranking can flip.

Common entry mistakes

• Entering the number of bottles as the amount: the amount in the container is the count of tablets or capsules in the whole package. Typing 2 for a two-bottle set makes one capsule look like it costs several dollars.
• Turning "2 capsules, twice a day" into 2 capsules, once a day: the daily amount is halved, so the monthly cost drops by half and the new-bottle date doubles.
• Mixing units for liquids and powders: if the amount in the container is in mL, the serving must be in mL too. When the serving is larger than the container, the calculator asks you to check the units.
• Different amount units across products: if one product lists IU and another lists mcg, the calculator cannot rank them per amount and falls back to monthly cost. If the label shows both, pick the same one for every product.
• Forgetting the days you skip: if you take a supplement on weekdays only but leave it on "Daily", the monthly cost comes out 7 ÷ 5 = 1.4 times too high.

Limits and cautions

• This calculator turns prices and servings into money. It does not tell you which supplements you need or how much is safe to take. The FDA recommends that people "talk to their doctor, pharmacist, or other healthcare professional before deciding to purchase or use a dietary supplement." If you are pregnant, have a medical condition or take medication, ask before you buy.
• Price per amount trusts the amount printed on the label as given. It does not account for absorption, the form of the ingredient, other ingredients or quality.
• Weekly schedules are averaged, so the real new-bottle date can be a day or two off. The new-bottle calendar also assumes you open every product on the same day.
• Prices are used exactly as you enter them. Discounts, rewards, shipping and price changes count only to the extent you put them in.
• Your list stays in this browser only when "Save in this browser" is on, and it is never sent to a server. A copied link carries your supplement names and values after the # in the address, so keep that in mind before sharing it.

As of: the source content was checked against the original pages on October 18, 2026. Every dollar amount in this article and in the calculator is an example.

Sources

• 01NIH Office of Dietary Supplements: Dietary Supplements: What You Need to KnowTaking more than you need costs more and might raise the risk of side effects; fortified foods can add up to more than you think (updated January 4, 2023)
• 02FDA: Information for Consumers on Using Dietary SupplementsTalk to a doctor, pharmacist or other healthcare professional before deciding to purchase or use a dietary supplement (content current as of October 21, 2022)

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