Cost per Unit Calculator

Cost per unit calculator for comparing product sizes and deals

When you are shopping, the sticker price is rarely the full story. Two products can look similar, but one can be significantly more expensive once you account for pack size, weight, volume, or the number of items inside. A cost per unit calculator fixes that by converting any total price into a comparable price per one unit, so you can pick the better value quickly and consistently.

This calculator is built for one dominant decision: choosing the better value between different pack sizes of the same type of product. That includes common cases like 750 g vs 1 kg, 500 ml vs 1 L, 12-pack vs 18-pack, or 2 kg bulk bag vs smaller bag. You enter the total price and the quantity for Option A, and the calculator returns the cost per unit. If you also enter Option B, it compares the two and tells you which one is cheaper and by roughly how much.

To use it well, treat the quantity as the total usable quantity you are actually getting. For example, if you are comparing liquid sizes, use milliliters for both. If you are comparing weight, use grams for both. If you are comparing counts, use the number of items in the box. The optional unit name is just for readability in the results, so you can label the output as per g, per ml, or per item.

Assumptions and how to use this calculator

• Prices are assumed to be in the same currency for both options. The calculator does not convert currencies.
• Quantities must be measured in the same unit when comparing two options (for example, both in grams, both in milliliters, or both as item counts).
• Quantity is assumed to be the total usable amount. If one option has more waste, leakage, or unusable content, adjust the quantity to match usable quantity.
• Taxes, delivery fees, and discounts are not automatically included. If they apply, include them in the total price you enter.
• Results are rounded to two decimals for readability. For tiny unit costs, use the included per 100 and per 1,000 unit figures to see the differences more clearly.

Common questions

What does “cost per unit” actually mean?

It is the total price divided by the total quantity. If you pay 49.99 for 750 g, the cost per unit is the price per 1 g. The same idea applies to ml, liters, items, or any other consistent unit.

Why do I see “per 100 units” and “per 1,000 units”?

Some products have very small per-unit costs, especially when the unit is 1 g or 1 ml. Rounding to two decimals can hide meaningful differences. Scaling up to 100 or 1,000 units makes the comparison easier to read without changing the underlying math.

Do I need to fill in Option B?

No. Option B is optional. If you only want the cost per unit for a single item, enter Option A only. If you enter any value for Option B, you should enter both the price and quantity so the comparison is valid.

What if one product uses a different unit, like kg vs g?

Convert them to the same unit before comparing. For example, 1 kg is 1,000 g, and 1 L is 1,000 ml. If you do not convert, the calculator will still compute each per-unit number, but the comparison between A and B will not be meaningful.

When should I NOT rely on cost per unit?

Cost per unit only answers value-for-money based on quantity. If quality, durability, performance, or brand matters, the cheaper unit price might not be the better choice. Also, if one option is likely to spoil before you use it, bulk may not be the real bargain.