Free · Everyday planning calculators

Package Unit Cost Comparison

Compare two packages by mass, volume or item count using consistent quantity units.

  • Formula & worked example
  • Private in your browser
  • No signup
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

A ten-item package for $20 costs $2 per item; 25 items for $40 costs $1.60 per item.

Unit cost = price / total quantity

Worked example

Enter these known values and leave the other values blank.

Type
Items
Number of items
10
Cost
20 USD
Number of items
25
Cost
40 USD
Price per item
2 USD /item
Price per item
1.6 USD /item
You save
0.4 USD /item

Assumptions and limitations

  • Compare like products and consistent units. Item counts are whole numbers; each included mass or volume is a per-item amount in the multi-item modes. Prices use the captured currency conversions, not a live exchange-rate feed.

Common questions

What does this estimate assume?

Compare like products and consistent units. Item counts are whole numbers; each included mass or volume is a per-item amount in the multi-item modes. Prices use the captured currency conversions, not a live exchange-rate feed.

Can I find a missing input?

Clear the unknown field and enter compatible known values. The controls retain supported inverse calculations, while rounded counts and one-way outputs stay directional.

References

Unit-price denominators are positive, package counts are whole numbers, and prices are nonnegative. These arithmetic bounds apply to the selected quantity mode without changing price equations. Item-mode comparison notes now compare item unit prices rather than the unrelated volume outputs, including the equal-price branch. Integer membership is checked with isInteger, so ordinary, tiny and large fractional counts are rejected even when tolerant floor equality would pass.

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