Unit Price Calculator
Compare two grocery packs by price per pound or kilo to find the deal.
What it does
Unit price divides each pack price by its weight so different sizes compare fairly. A big bag almost always looks dearer at the register while running cheaper per pound, and the shelf tag math proves it line by line.
The tool above compares two packs in imperial or metric. Imperial enters ounces and reports dollars per pound, metric enters grams and reports per kilo, with the winner and the saving percent in the note.
The default sets Pack A at $4.50 for 16 oz against Pack B at $8 for 32 oz: $4.50/lb versus $4.00/lb, so B wins by 11.1%. The metric mirror of 453.6 g and 907.2 g reads $9.92/kg against $8.82/kg with the same gap.
FTC consumer guides and NIST weights and measures offices both teach the same division: price divided by quantity in a common unit. Store tags already print it small; this page redoes it when tags use mismatched units.
How to use
- Pick imperial for ounces and pounds or metric for grams and kilos.
- Enter Pack A price with its size in that system.
- Enter Pack B price with its size in that system.
- Read both unit prices first for the fair comparison.
- Buy the winner only when brand, recipe, and use by dates match.
Formula
- oz / 16
- Pack weight converted to pounds.
- grams / 1000
- Pack weight converted to kilos.
- gap / higher
- Saving share against the dearer unit price.
Zero prices are allowed for freebies and return zero unit prices with a tie or a clear winner. Equal unit prices report a tie instead of forcing a false gap.
Worked example
Example: $4.50 for 16 oz vs $8 for 32 oz
Imperial defaults: A 4.50/16 oz, B 8/32 oz.
- Pack A weight: 16 / 16 = 1 lb. Unit: 4.50 / 1 = $4.50 /lb.
- Pack B weight: 32 / 16 = 2 lb. Unit: 8 / 2 = $4.00 /lb.
- Winner: $4.00 beats $4.50, so Pack B wins.
- Gap: (4.50 - 4.00) / 4.50 = 11.1%.
- Tool shows $4.50 /lb, $4.00 /lb, Pack B wins.
Reference table
| Pack | Imperial | Metric |
|---|---|---|
| A: $4.50 | $4.50 /lb (16 oz) | $9.92 /kg (453.6 g) |
| B: $8.00 | $4.00 /lb (32 oz) | $8.82 /kg (907.2 g) |
| Winner | Pack B by 11.1% | Pack B by 11.1% |
Limits
- Same recipe only. Quality, waste, and storage change value.
- Weight basis here. Counts and volume packs need their own units.
- Coupons and loyalty prices need entering as the paid price.
- Perishables can waste the saving if the big pack spoils.
Common mistakes
- Comparing per pack prices instead of per unit.
- Mixing ounces with fluid ounces on drinks.
- Ignoring drained weight on canned goods.
- Trusting mismatched tag units across brands.
- Buying big perishables that spoil before use.
Try it yourself
Quick checks. Answers sit tucked under each question.
$3 for 12 oz vs $5 for 24 oz?
$4.00/lb against $3.33/lb. Second wins by 16.7%.
$4.50 for 453.6 g in per kg?
4.50 / 0.4536 = $9.92 /kg.
Tie case: $5 for 16 oz vs $10 for 32 oz?
Both $5.00/lb. Tie.
Questions
How do you find unit price?
Price divided by weight in a common unit: $8 for 32 oz is 8 / 2 = $4.00/lb.
Ounces or pounds?
Enter ounces here; the page reports per pound. Metric enters grams and reports per kilo.
Bigger pack always cheaper?
Often but never always. This page catches the cases where it is not.
What about fluid ounces?
Use weight ounces for solids. Fluids need price per liter or gallon instead.
Drained weight?
Divide by the drained grams on the label for canned fish and veg, not the full can.
Why did B win by 11.1%?
Gap 0.50 over higher 4.50 is 11.1%. Same ratio in metric: 1.10 over 9.92.