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The price must cover the complete package or bundle.
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Examples: 16 oz, 500 g, 1.5 L, or 24 count.
Multiplies the printed size for a multipack or case.
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Use the full price for the option being compared.
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Weight compares with weight, volume with volume, and count with count.
Multiplies the printed size for a bundle or case.
packs
Match Package A follows its shelf unit; explicit targets keep every artifact on one basis.
Optional short label used in results and exports.
Optional short label used in results and exports.
The neutral default is 0%.
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The neutral default is zero; omit mixed-cart fees.
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The neutral default is 100% usable.
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Examples: $, EUR, GBP, RM, or SGD.
Choose 2 through 6 display decimals.
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PackageEffective priceUsable sizeUnit priceFindingCopy
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The chart renderer is unavailable. The same comparison remains available in Unit Price Ledger.

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The chart renderer is unavailable. The same break-even values remain available in Shelf Price Limits.

Break-Even Calculator Calculate break-even and target-profit unit sales, then test price and cost changes against planned profit and margin of safety.
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Profit Margin Calculator Calculate profit margin and markup from revenue and direct cost, then test target pricing plus optional expenses and percentage fees.

A larger package is not automatically the better buy. Unit price removes package size from the comparison by expressing each option on the same basis, such as price per ounce, per kilogram, per 100 millilitres, or per item. That common denominator makes a small jar and a family pack comparable even when their shelf prices and printed sizes look unrelated.

The comparison is only meaningful when the quantities describe the same kind of measure. Weight can be converted between grams, kilograms, ounces, and pounds; volume can be converted between millilitres, litres, U.S. fluid ounces, and U.S. gallons. A count cannot be converted honestly into weight or volume without product-specific information.

  • Multiply the printed size by the pack count for cases and multipacks.
  • Include only fees and discounts that apply equally to each option in the comparison.
  • Reduce the usable percentage when trimming, spoilage, breakage, or other expected waste differs from the labelled amount.
  • Compare quality, shelf life, storage space, cash outlay, and the amount you can realistically use alongside the unit price.

A lower price per unit answers a narrow cost question. It does not make a bulk purchase economical when the excess will expire, nor does it establish that two products have equal quality or performance. The useful decision combines normalized price with the quantity that will actually be consumed.

How to Use This Tool:

Enter each complete package as sold, then choose one comparison basis that both quantities can share.

  1. Enter the price, printed size, unit, and pack count for Package A and Package B. A 6-pack of 500 ml bottles is 500 ml with a pack count of 6, not 3,000 ml with a pack count of 6.
  2. Choose Compare as. The automatic option follows Package A's shelf unit; an explicit target such as per 100 g or per litre keeps every result on that basis.
  3. Add a shared discount or checkout fee only when the same adjustment applies independently to either choice. Set Usable amount below 100% when part of each package will not be used.
  4. Check the buying signal and shelf-price limit. If the units belong to different families, correct the weight, volume, or count selection before comparing prices.

Interpreting Results:

Compare the two Unit price values on the same target basis. The spread is the difference between the higher and lower unit prices; its percentage is measured against the higher value. A tie is reported when the difference is no more than a very small numeric tolerance.

The 8% material-spread signal is a planning cue defined for this comparison, not a legal or retail threshold. The break-even shelf price shows how much a package of a given size could cost while matching the currently cheaper usable-unit rate. A negative or zero practical limit can occur when the shared checkout fee consumes the entire allowance.

Technical Details:

Each package quantity is converted to a base quantity within its family: grams for weight, millilitres for volume, or individual units for count. The same usable fraction is then applied to both packages. Shelf-price adjustments are applied separately to each option before division, so the comparison remains symmetric.

Formula Core:

The effective price combines the common discount and fee, while usable quantity combines printed size, pack count, conversion factor, and usable fraction.

Peff=P×(1−d)+f
Qusable=q×n×c×u
Punit= PeffQusable÷b
Plimit= r×Qgross×u−f 1−d
FamilyBase quantitySelected exact conversions
Weightgram1 kg = 1,000 g; 1 oz = 28.349523125 g; 1 lb = 453.59237 g
Volumemillilitre1 L = 1,000 ml; 1 U.S. fl oz = 29.5735295625 ml; 1 U.S. gal = 3,785.411784 ml
Countindividual unitCount, serving, sheet, and piece each convert one-for-one

Here d is the discount percentage divided by 100, f is the fee, u is the usable percentage divided by 100, b is the base amount represented by the chosen target, and r is the lower effective price per usable base quantity. Full precision is retained for comparison and break-even arithmetic; the selected two to six decimals affect display only.

Worked Examples:

Two jars labelled in ounces

A 16 oz jar at $4.79 costs about $0.2994 per ounce. A 28 oz jar at $7.99 costs about $0.2854 per ounce, making the larger jar cheaper by roughly $0.0140 per ounce even though its shelf price is higher.

Usable quantity changes the answer

If both packages lose 20% to trimming, each usable quantity becomes 80% of its label amount and both unit prices rise by the same proportion. If waste differs between products, run separate comparisons or calculate product-specific usable amounts before treating the result as decisive.

References: