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Unit price: which one costs less

The big jar or the small one. The store brand in ounces or the name brand in pounds. Two for five dollars, or one for $2.79. Shelf prices are hard to compare when the sizes are different. This page takes the price and the size of each choice and shows what each one costs for the same amount: per ounce, per pound, per 100 grams, per quart, or for each one. There is no account and no price, and it works with one hand in a store aisle.

Private by design. Nothing you type is sent anywhere. What you add is kept in this browser on this device from the first time you press Add, so a list is still there if the page reloads, and one button erases it. This page runs no analytics or tracking. How we handle privacy.

This tool needs JavaScript. You can do the same count with any calculator: divide the price by the size. A 16 oz jar at $3.99 is 3.99 divided by 16, about 24.9 cents an ounce. A 2 lb jar at $6.99 is 32 oz, and 6.99 divided by 32 is about 21.8 cents an ounce.

Good to know

How it works

What I am comparing: one line for each choice, with its price, the size of one, and what the size is measured in. The name is optional.
How many for that price stays at 1 for one package. For a tag that says 2 for $5, type 5 as the price and 2 as how many. For a pack of 6 cans of 12 fl oz each, type 6 as how many and 12 as the size.
Which costs less lists the choices with the lowest price per unit first, and says what each of the others would cost at that lowest price.
The choices do not have to use the same measure. Ounces, pounds, grams and kilograms are compared with each other. So are fluid ounces, pints, quarts, gallons, milliliters and liters.
Count is for anything sold by the number: eggs, diapers, sheets on a roll, loads of detergent, tablets. Use it only when each choice counts the same thing.
Print, Copy as text and Download (.txt) give the comparison to keep or send.

How the page counts

Amount: how many, times the size of one.
Price per unit: the price divided by the amount. That is all of it.
To compare ounces with pounds or grams, the page first turns every weight into grams: 1 pound is 453.59237 grams, and 1 ounce is a sixteenth of a pound, 28.349523125 grams.
It turns every liquid measure into milliliters: 1 U.S. gallon is 3,785.411784 milliliters. A quart is a quarter of a gallon, a pint is an eighth, and a fluid ounce is 1/128 of a gallon, about 29.57 milliliters.
The National Institute of Standards and Technology (NIST) prints the same factors, rounded to seven figures, in its Guide to the SI, Appendix B.9: 0.4535924 kilograms to the pound, 28.34952 grams to the ounce, 3.785412 liters to the U.S. gallon, and 29.57353 milliliters to the U.S. fluid ounce.
These are U.S. measures. The same NIST table lists the U.K. (Imperial) gallon at 4.54609 liters, which is larger, so a U.K. pint, quart or gallon should not be typed here as a U.S. one.
Prices per unit are rounded for showing. The order is worked out before rounding.

We read the NIST page on October 10, 2026 (NIST dates its last update August 18, 2025). The numbers are NIST’s; the counting is ours.

What a price per unit does not tell you

It does not know if you will use it all. A large size that spoils, or that there is nowhere to keep, costs more than its tag says.
It does not know what you can pay today. The lowest price per unit often comes with the highest price at the register. When that happens here, the page says so.
It cannot compare a weight with a volume, or either one with a count. An ounce of weight is not a fluid ounce. Those go in separate lists.
It does not know what is inside. Two brands can differ in strength, in how much water is in the can, or in how many you need. A “load” or a “serving” is whatever each maker says it is.
It counts tax, a bottle deposit, a coupon or a card price only if they are in the price you type.
It does not know any store’s prices, and it does not tell you what to buy.
It holds one list of up to 12 choices, and the list does not move to another phone or computer by itself.

If there is not enough for food

Comparing prices stretches money. It does not make money that is not there.
On this site: Food help and Help with money.
Calling 211 reaches a local helpline in most of the U.S. that knows what help is near you.

Tools that go with this

Shopping list: the total of the list before the register, and the cart added up as you go.
Money plan: one month of money on one page.
Bills: one real month, each bill with its due date, ticked off when paid.
Debt payoff planner: how long a pile of debts takes, and what the interest adds up to.
All the free tools, and how to save them on your phone.

Arithmetic, not advice. This tool divides the numbers you type. It does not know your kitchen, your week or your budget. If things are so tight that you are thinking about ending your life, call or text 988 (in the U.S.), or open Get help now. In an emergency, call 911.

The tool and the wording around it were written with AI (Claude) for Scarlet Beast (our AI policy); the prices and the names are yours. There is no AI inside this tool: it only multiplies and divides. It has been checked by a program, not yet used by people in a store. What it keeps is listed on My data on this device. Also in Spanish: Precio por unidad; both pages keep the same list on this device. Found a mistake? Email [email protected].