Price Comparison Calculator
Which option is cheaper per unit?
Compare two options' cost per unit to identify the cheaper buy at different package sizes or prices. Enter option a price and see the result instantly.
What this tool does
Enter two options' prices and unit quantities. The tool shows cost per unit for each and the winner.
Enter Values
Formula Used
Spotted something off?
Calculations, display, or translation — let us know.
Disclaimer
Results are estimates for educational purposes only. They do not constitute financial advice. Consult a qualified professional before making financial decisions.
4.50 for 500g vs 7.20 for 900g: 0.009/g vs 0.008/g — bigger pack is 11% cheaper per gram. Reveals hidden pricing tricks. Common example: some 'bulk' sizes are actually per-unit more expensive than standard size.
Quick example
With option a price of 4.5 and option a quantity of 500 (plus option b price of 7.2 and option b quantity of 900), the result is Option B. Change any figure and watch the output shift — it's often more useful to see the pattern than to memorise the formula.
Which inputs matter most
You enter Option A Price, Option A Quantity, Option B Price, and Option B Quantity. Two inputs usually tip the answer one way or the other. Identify which ones matter most by flipping each value past a round threshold and watching whether the winning option changes.
What's happening under the hood
Price divided by quantity for each option. The formula is listed in full below. If the number looks off, you can retrace the calculation by hand — that's the point of showing the working.
What the bill doesn't show
Standing charges, discounts, and usage tiers all blur the effective rate. The calculation here backs out the total so you're comparing apples to apples across providers, regardless of how each one packages the price.
What this doesn't capture
Usage varies month-to-month; tariffs change; discounts come and go. The figure here is a clean baseline — your actual annual bill will fluctuate around it. Use the calculation to benchmark providers, not as a prediction of a specific bill.
Where to go next
This calculation rarely sits alone in a planning exercise. If you're running these numbers, you'll probably also want the bulk buy savings calculator, the break even price calculator, and the price per unit calculator — each one answers a different question in the same territory. Treating them as a set rather than in isolation usually produces a more honest picture.
Price comparison produces a winner based on the inputs provided.
Inputs
This example uses typical values for illustration. Adjust the inputs above to match a specific situation and see how the result changes.
Sources & Methodology
Methodology
Price divided by quantity for each option.
References
Frequently Asked Questions
Is cheaper always better?
Why do shops not show unit prices?
Bulk vs single — rule of thumb?
Same units required?
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