Unit Price Comparison

Overview

A shopping comparison calculator that converts two products into price per unit — per gram, kilogram, millilitre, litre, piece, or metre — and tells you which one is cheaper per unit and by what percentage. It turns package-size arithmetic at the shelf into a single comparable number.

How It Works

For each product, enter its price, its quantity, and its unit from a dropdown covering g, kg, ml, l, pcs, and m. The tool divides price by quantity for both and displays the unit price of each, highlighting the cheaper one in green with a line stating how much better value it is in percentage terms. If both cost the same per unit, it says so instead of arbitrarily picking a winner.

Step-by-Step Usage Guide

1. Enter product A's price and package quantity, and pick its unit.
2. Do the same for product B, using the same unit.
3. Read both unit prices and the highlighted cheaper option.
4. Use the percentage figure to judge whether the saving justifies a bigger package.

Technical Specifications & Standards

Unit price is price divided by quantity, with the quantity guarded by a tiny epsilon so a zero entry cannot divide by zero. The percentage advantage is computed as the absolute difference between the two unit prices divided by the higher one, so '12.5% better value' means the winner costs 12.5 percent less per unit than the loser. One limitation to respect: the tool compares the two unit prices numerically without converting units. If you enter product A in grams and product B in kilograms, the comparison is meaningless — 4.50 per g versus 8.90 per kg are different scales — and the cheaper badge would be wrong. Use the same unit for both products (the defaults are both in grams for this reason), or convert one yourself first: 1 kg equals 1,000 g and 1 litre equals 1,000 ml. Also note the tool assumes the products are genuinely comparable goods; a larger package is only better value if you will actually use all of it before it spoils, which no arithmetic can decide for you.

Targeted Use Cases

• Comparing a 500 g pack with a 1 kg pack at different prices.
• Deciding between a 330 ml bottle multipack and a 1.5 litre bottle.
• Checking whether the 'family size' really costs less per piece.
• Comparing fabric or cable priced per metre in different roll lengths.

Notes & Gotchas

• Always select the same unit for both products, or convert before comparing.
• Compare like with like — same product category and quality, different sizes.
• Factor in wastage and shelf life; the cheapest per gram is not cheapest if half spoils.
• Watch promotional rounding: enter the actual ticket price, not the rounded tag.

Frequently Asked Questions