Unit Price Calculator

Compare two pack sizes on the same measurement basis. Enter each offer’s full price and the amount in every inner pack; the calculator handles compatible unit conversions.

CurrencyUse one currency for all amounts. This changes labels only; it does not convert money or change local rules.

Compare cost perChoose a unit of the same dimension as both offers: weight, volume or item count.

Option A — total offer priceUSDPrice for all packs in this offer together, not the price of one inner pack.

Option A — amount per inner packgUse net contents, not gross shipping weight.

Option A — amount unitChanging to a compatible unit converts the amount. Changing dimension requires entering the new amount yourself.

Option A — inner packs in offerpacksFor a single container, enter 1.

Option B — total offer priceUSDUse the same currency and consistent treatment of shipping, tax and discounts as Option A.

Option B — amount per inner packkg

Option B — amount unit

Option B — inner packs in offerpacksExample: a six-pack contains 6 inner packs, with each pack’s volume entered above.

Calculation results

Lower unit-price offer

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How to use this calculator

Enter full offer prices

The price belongs to the entire offer. If a pack of six bottles costs 12, enter 12 as price, 6 as pack count and one bottle’s volume as amount.

Use comparable net contents

Compare weight with weight, volume with volume or count with count. Fluid ounces measure volume; ordinary ounces measure weight.

Pick a shared basis

Cost per kilogram, liter or item makes differently sized offers comparable. The tool converts compatible units before dividing.

Interpret the saving

The percentage is the lower unit price’s saving relative to the higher unit price for equal quantities. It does not claim that buying whole packages gives the same cash saving.

Formula and worked example

Offer quantity = amount per inner pack × inner-pack count
Convert both quantities to one compatible comparison unit
Unit price = total offer price ÷ total quantity in comparison units
Unit-price difference = higher unit price − lower unit price
Saving relative to higher price = difference ÷ higher unit price × 100

Option A costs 5 for 500 g, so its unit price is 10 per kg. Option B costs 8 for 1 kg, so its unit price is 8 per kg. Option B is cheaper by 2 per kg, or 20% relative to Option A’s unit price. This is an equal-quantity comparison; Option B still costs 8 at checkout while Option A costs 5.

Multipack price and quantity must cover the same offer

Illustrative offers in one currency. This example uses volume units throughout and includes no extra shipping or tax.
Offer	Total contents	Price per liter
6 × 500 mL for 12	3 L	4.00
4 × 1 L for 14	4 L	3.50
1 × 2 L for 8	2 L	4.00

Frequently asked questions

Is the cheaper package always the better unit price?

No. A smaller package can cost less at checkout but more for each kilogram, liter or item. This tool compares equal quantities rather than headline package prices.

Can I compare grams with milliliters?

Not directly. Mass and volume are different dimensions, and conversion would require the product’s density. This calculator deliberately rejects that comparison instead of assuming every product has the density of water.

Are ounces and fluid ounces the same?

No. An ounce here is an avoirdupois weight unit. A US fluid ounce is a volume unit. Choose the form actually stated on the product, and do not use these US volume choices for Imperial quantities.

How do I enter a buy-one-get-one offer?

Enter the total price paid and the total number of included inner packs. For two identical 500-g packs costing 5 together, enter price 5, amount 500 g and pack count 2.

What if one offer is free or both prices are equal?

A zero-price offer is allowed. If only one is free, its unit-price saving is 100%. If both unit prices are equal, the result reports a tie and zero saving. Product quality, minimum spend and promotional restrictions are not evaluated.

Methodology and sources

Compares two fixed offers using net quantity and one shared currency. It does not compare product quality, edible yield, dilution strength, expiry risk or the whole-package cost of meeting a particular shopping list. Prices should include any comparable charges you want considered. US liquid volume and avoirdupois weight units are used; Imperial volume is not inferred.

NIST — uniform unit pricing — Why comparison on a consistent quantity basis is useful.
NIST Handbook 44 — measurement tables — Mass and US liquid-volume definitions used for conversions.

Sources checked September 1, 2026. Referenced organizations do not endorse Efficienco. Offers are compared before display rounding. Unit prices use up to four decimal places; very small values use scientific notation.