CompareForgecalculate tool
Unit Price Calculator
Enter price and quantity for two options to compare cost per unit — per ounce, gram, ml, GB or any unit — and see which pack is the better deal.
How This Tool Works
Unit price divides each option’s price by its quantity, putting both offers on a common per-unit scale. The tool then compares the two unit prices, identifies the better deal, and expresses the gap as a percentage of the higher unit price.
That normalization is what makes differently sized packs comparable. A bigger package often has a lower unit price, but not always — bundle pricing, promo sizes and import premiums break the assumption often enough that checking is worth ten seconds.
How to Use It
Type a unit name first (oz, ml, g, GB, metres, servings — anything consistent), then enter price and quantity for both options. Quantities must be in the same unit for the comparison to mean anything.
For groceries use weight or volume; for storage use gigabytes; for cable use metres; for subscriptions use months of service. If the two options use different units, convert them first.
Understanding the Results
The two unit prices are the core numbers — lower is cheaper per unit. The savings percentage is measured against the higher unit price, telling you how much of a premium the worse deal carries.
For everyday shopping, most regions require unit pricing on shelf labels; this tool lets you redo that math at home for online offers, bulk orders, or multi-packs where the label is missing.
Example
A 500 ml bottle costs $4.50; a 1,000 ml bottle costs $8.00. Entered as 500 and 1,000 ml, the tool returns $0.009 versus $0.008 per millilitre — the larger bottle is 11.1% cheaper per millilitre even though its sticker price is higher. Set the unit to “100 ml” and enter 5 and 10 instead, and you get $0.90 versus $0.80 per 100 ml: the percentage gap is identical either way, only the scale changes.
Storage edition: 100 GB at $5.00/month versus 500 GB at $15.00/month. Per GB that is $0.05 versus $0.03 — the bigger tier is 40% cheaper per GB, but only worth it if you actually use the space. Unit price measures the deal, not your needs.
Important Considerations
A better unit price only matters if you will consume the quantity. Buying double the size to ‘save’ 10% is a loss if half expires or goes unused — pair this with the Cost Per Use Calculator for usage-based value.
Watch for hidden differences: concentrated formulas, different concentrations, membership-only prices, or included features. Unit price normalizes quantity, not quality.
The tool does not fetch live store prices. Enter the numbers you actually see at checkout.
Methodology & Data
- Unit price = price ÷ quantity, computed separately for both options.
- Savings % = (higher unit price − lower unit price) ÷ higher unit price × 100.
- Quantities must be greater than zero and expressed in the same unit.
- All math is client-side; no prices or inputs are stored or transmitted.
Related Tools
Related Guides
- Unit Pricing: How to Compare Prices Fairly
How to normalize prices across sizes, periods and packages - unit price, per ounce, per seat, per month - so discounts compare fairly.
- How to Compare Subscription Plans Properly
A repeatable method for comparing subscription tiers - normalize billing periods, weight the features you use, and catch pricing traps.
- How Much Phone Storage Do You Need?
A practical method: what actually consumes storage, how to project your usage over the years you keep the phone, and the real price of each storage step from our recorded variant prices.
Common Questions
What is a unit price?
Unit price is the cost for one standard unit of measure — per ounce, per 100 ml, per gigabyte, per metre. It is calculated as price divided by quantity.
How do I compare two different pack sizes?
Enter each pack’s price and quantity in the same unit. The tool returns both unit prices and tells you which pack is cheaper per unit and by how much.
Is the bigger size always the better deal?
No. Unit price often falls as size grows, but promos, small-pack discounts and premium products break the pattern. The calculator shows the real numbers rather than assuming.
Can I use this for subscriptions?
Yes — treat months of service as the quantity. For comparing monthly versus annual billing specifically, the Monthly vs Annual Savings Calculator gives a fuller picture including cash flow.
Does this work for currencies other than dollars?
Yes. The math is currency-agnostic as long as both prices are in the same currency. The $ sign is only a label.