Pizza Size Comparison
Pizza scales with area, not diameter — that is, with the square of the diameter. One 45 cm pizza beats two 30 cm ones: 1.5× the diameter is 2.25× the area.
Your numbers
Result
1.125×
Area
1,590.4cm²
Difference
1,413.7cm²
What it means
One 45 cm pizza is 12.5% more pizza than 2 × 30 cm.
Formula
Area = π × (Pizza A diameter ÷ 2)² vs How many B × π × (Pizza B diameter ÷ 2)²
This assumes equal crust thickness. Thin and deep-dish bases differ in volume.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Pizza A diameter (cm)The diameter of the first pizza. | 45 | 1 and up |
| Pizza B diameter (cm)The diameter of the second pizza. | 30 | 1 and up |
| How many BHow many of the smaller ones you order. | 2 | 1 ~ 20 |
Step by step
Quick reference table
Results when only Pizza A diameter (cm) changes and everything else stays put.
| Pizza A diameter (cm) | Result (×) | Area (cm²) | Difference (cm²) |
|---|---|---|---|
| 22.5 | 0.281 | 397.6 | 1,413.7 |
| 33.8 | 0.635 | 897.3 | 1,413.7 |
| 45 | 1.125 | 1,590.4 | 1,413.7 |
| 67.5 | 2.531 | 3,578.5 | 1,413.7 |
| 90 | 4.5 | 6,361.7 | 1,413.7 |
What each result means
| Result | At default values |
|---|---|
| Result (×)What the formula gives back — the answer this page is for. | 1.125 |
| Area (cm²)The space a shape covers — length squared. | 1,590.4 |
| Difference (cm²)The gap between two values — a quantity, not a rate. | 1,413.7 |
Common mistakes
This assumes equal crust thickness. Thin and deep-dish bases differ in volume.
Glossary
- Pizza A diameter
- The diameter of the first pizza.
- Pizza B diameter
- The diameter of the second pizza.
- How many B
- How many of the smaller ones you order.
- Result
- What the formula gives back — the answer this page is for.
- Area
- The space a shape covers — length squared.
- Difference
- The gap between two values — a quantity, not a rate.
Frequently asked questions
Q. How is Pizza Size Comparison calculated?
Area = π × (Pizza A diameter ÷ 2)² vs How many B × π × (Pizza B diameter ÷ 2)² — Pizza scales with area, not diameter — that is, with the square of the diameter. One 45 cm pizza beats two 30 cm ones: 1.5× the diameter is 2.25× the area.
Q. Can you walk through an example?
With Pizza A diameter 45cm, Pizza B diameter 30cm, How many B 2, the answer is Result 1.125×.
Q. What do I need to enter?
Enter Pizza A diameter, Pizza B diameter, How many B. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Pizza A diameter (cm) moves the answer to Pizza A diameter (cm) 22.5 → Result (×) 0.281 and Pizza A diameter (cm) 90 → Result (×) 4.5. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
This assumes equal crust thickness. Thin and deep-dish bases differ in volume.
Related calculators
Keep your length units consistent across inputs — mixing centimetres and metres throws results far off.