Price Comparison Calculator — Find the Cheapest Price per Unit
Compare prices per gram, ounce, liter, or square foot across products — or by the hour, month, or year for subscriptions and rentals
See which option is...
When Should You Use This Calculator?
- Checking whether a bigger or "family size" pack is really cheaper per unit
- Comparing brands, stores, or a sale price against the regular size
- Confirming that bulk and warehouse-club multipacks actually save per unit
- Comparing anything sold by size — storage per GB, electricity per kWh, materials per metre
- Adjusting for discounts, tax, waste, or servings when they change which option wins
How to Use This Calculator
- Enter each product’s price and size — a worked example is filled in to start.
- Set the unit for each item; grams, kilograms, ounces, litres and more are converted automatically.
- Read the result: the lowest price per unit is highlighted as the best deal.
- Optional: switch to Discount & Tax or Real Cost mode to adjust for coupons, tax, waste, or servings.
- Copy or export the comparison for your shopping list.
Key Features:
- Compare multiple scenarios side-by-side
- Compare any number of products or package sizes and highlight the cheapest per unit
- Automatic unit conversion — mix grams, kilograms, ounces, litres, packs, even GB or kWh
- Optional Discount & Tax and Real Cost modes adjust for coupons, sales tax, waste, and servings
- Savings versus the next-best option, projected monthly and yearly
Formula
Unit Price = Adjusted Price ÷ Effective Quantity
- Discount & Tax mode applies discounts and sales tax to the price before ranking.
- Real Cost mode adjusts the usable quantity via yield percent and servings.
- A lower unit price means the better value.
Frequently Asked Questions
How do I know which item is cheaper?
Compare the price per unit, not the total price. Enter each product’s price and size and the calculator works out the cost per unit for each, then highlights the lowest one as the best deal. A cheaper sticker price often loses once you account for how much you actually get.
Is the bigger size always the better deal?
No. Larger and "family size" packs are usually — but not always — cheaper per unit. Some stores price the bigger size at a higher cost per unit, so the smaller pack wins. The only reliable way to tell is to compare the unit price, which is what this calculator does.
What is the unit price formula?
Unit price = total price ÷ quantity. For example, a 500 g pack at $3.00 has a unit price of $0.006 per gram. The calculator applies this to every item and normalises the units, so you can compare grams vs kilograms, ounces vs pounds, and so on.
Can I compare items sold in different sizes or units?
Yes. Choose a Category — Weight, Volume, Length, Area, Quantity, Data, Energy, or Time — and the unit for each item within it (grams vs kilograms, ounces vs pounds, US vs UK pints, square feet vs square yards, and so on). The calculator converts everything to a common unit before ranking, so the comparison is fair even when the sizes or units do not match.
Can I compare subscription, rental, or hourly rates?
Yes — select the Time category to compare anything priced per minute, hour, day, week, month, or year: a monthly vs. annual subscription, an hourly freelance or labor rate, or a daily vs. weekly rental. The calculator converts every price to the same time unit (e.g. dollars per month) before ranking, the same way it does for groceries.
What do the Discount & Tax and Real Cost modes do?
Simple mode compares the plain price per unit. Discount & Tax mode applies a coupon or sale and adds sales tax to each item before ranking, which can flip the winner. Real Cost mode goes further, adjusting for usable yield or serving count so you compare the true cost of what you actually use — useful for fresh food that gets trimmed or wasted.
How are the savings projections calculated?
When at least two valid items are entered, the calculator estimates the saving between the best and next-best option, then projects monthly and yearly savings using how often you say you buy per month.
Can I export my Unit Price Comparison calculations?
Yes. In guest mode you can export your calculations to JSON. Signing in adds PDF and CSV export. Click the export button to download your results — useful for record-keeping, sharing, or importing into other tools.
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