Pizza Size Calculator
Compare two pizzas by size and price; work out edible area, cost per cm², and crust ratio to find the better value.
Input Data
Results
At a glance:Compare two pizzas by size and price; work out edible area, cost per cm², and crust ratio to find the better value.
Formula
Edible area = π × (diameter ÷ 2 − crust width)².
Cost / cm² = price ÷ edible area.
$$A = \pi \left( \frac{d}{2} - e \cdot n \right)^2$$$$c = \frac{p}{A}$$$$\Delta = \left(\frac{c_B}{c_A} - 1\right) \times 100\%$$How to Use
- Enter each pizza's diameter and price.
- Enter the crust width and whether you eat the crust.
- The calculator returns edible area, topping area, and cost per cm² for both, plus the difference.
FAQ
Why does doubling the diameter make the area four times larger?
Circle area = πr², which scales with the square of the radius. Doubling the diameter doubles the radius, so the area becomes 2² = 4 times larger.
How is 'cost per cm²' different from 'cost per inch'?
Cost per inch only compares diameters and ignores the squared growth of circle area, which is misleading. Cost per cm² directly reflects how much pizza you get for your money and is the more accurate metric.
Does eating the crust or not affect the result much?
It matters a lot. The crust is excluded from edible area; if you skip the crust, a small pizza has a higher crust proportion, so its edible area is discounted more, which can make the large pizza better value.
What does the edible-edge factor mean?
The edible-edge factor is the share of the crust ring you eat: eat all = 0, half = 0.5, none = 1. A larger number deducts more crust area.
Why look at the sign of the cost difference?
Cost difference = (B cost/cm² ÷ A cost/cm² − 1) × 100%. Positive means B is pricier, negative means B is better value; a larger magnitude means a clearer difference.
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References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.