# How I compare unit prices when pack sizes differ

A beginner-friendly guide to comparing products by price per gram, millilitre, item, or other unit.

- Date: 2026-09-27
- URL: https://ilham.dev/posts/how-to-compare-unit-prices-when-pack-sizes-differ/
- Markdown: https://ilham.dev/posts/how-to-compare-unit-prices-when-pack-sizes-differ/index.md
- Tags: shopping, unit-price, math, tools
- Reading time: 2 min


A larger package is not always cheaper. Unit price comparison puts products on the same scale.

The [Unit Price Comparator](/tools/unit-price-comparator/) tool handles the repetitive part so I can focus on checking whether the result makes sense.

## The simple idea

A larger package is not always cheaper. Unit price comparison puts products on the same scale.

I still treat the output as something to review, especially when it affects money, dates, privacy, or production data.

## Step 1: Enter each product price

Enter each product price.

## Step 2: Enter the quantity or size

Enter the quantity or size.

## Step 3: Choose the same unit for every item

Choose the same unit for every item.

## Step 4: Compare price per unit

Compare price per unit.

## Step 5: Watch for different units like grams and kilograms

Watch for different units like grams and kilograms.

## Step 6: Include shipping or fees when they matter

Include shipping or fees when they matter.

## Step 7: Use the result as a guide, then consider quality and waste

Use the result as a guide, then consider quality and waste.

## My checklist

Before I trust the result, I check:

- Enter each product price.
- Enter the quantity or size.
- Choose the same unit for every item.
- Compare price per unit.
- Watch for different units like grams and kilograms.
- Include shipping or fees when they matter.
- Use the result as a guide, then consider quality and waste.

A small tool is most useful when it makes the work visible and easy to verify.