Rex says
Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.
Try a scenario
Click to load — tweak from there.Inputs
Result
Area ratio (new ÷ old)
1.83
Batter needed vs recipe
183%
Relative batter depth
55%
Recipe pan area
64.0
Your pan area
117.0
Psst — share this and help Rex grow
One click, a permanent link with your numbers baked in.
How to use this
- 1Enter recipe pan width/diameter (in).
- 2Enter recipe pan length (same as width if round) (in).
- 3Enter your pan width/diameter (in).
- 4Enter your pan length (in).
- 5Read your area ratio (new ÷ old) on the right — it updates as you type.
- 6Hit Share to keep the scenario or send it to someone.
About this calculator
Only have a 9×13 when the recipe wants two 8-inch rounds? Compare the surface area of what the recipe calls for against the pan you own, and see how much batter to use and whether the bake will run deeper or shallower.
Worked example
Using the values the calculator loads with:
Inputs
- Recipe pan width/diameter: 8 in
- Recipe pan length (same as width if round): 8 in
- Your pan width/diameter: 9 in
- Your pan length: 13 in
Results
- Area ratio (new ÷ old): 1.83
- Batter needed vs recipe: 183%
- Relative batter depth: 55%
- Recipe pan area: 64
- Your pan area: 117
What each field means
Inputs
- Recipe pan width/diameter (in)
- The recipe pan width/diameter used in the calculation, measured in in. Starts at 8 in so you have a working example on load.
- Recipe pan length (same as width if round) (in)
- The recipe pan length (same as width if round) used in the calculation, measured in in. Starts at 8 in so you have a working example on load.
- Your pan width/diameter (in)
- The your pan width/diameter used in the calculation, measured in in. Starts at 9 in so you have a working example on load.
- Your pan length (in)
- The your pan length used in the calculation, measured in in. Starts at 13 in so you have a working example on load.
Results
- Area ratio (new ÷ old)
- Returned as a decimal number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Batter needed vs recipe
- Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Relative batter depth
- Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Recipe pan area
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Your pan area
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
What if the ratio is close to 1?
Anything between about 0.9 and 1.1 bakes essentially the same. Keep the recipe as written.
How do I adjust bake time?
Shallower batter bakes faster. Start checking 5–10 minutes early when your depth number is below 100%.
Accuracy and limitations
- Estimates assume standard, average conditions — local rules, pricing, and materials vary.
- Results are rounded for readability; add a buffer before ordering, booking, or committing.
- Double-check anything with a real cost attached against a local quote.
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Baking Pan Size Conversion Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/baking-pan-conversion
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/baking-pan-conversion" target="_blank" rel="noopener">Baking Pan Size Conversion Calculator — RevenueLab</a> (2026).</p>
Source: [Baking Pan Size Conversion Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/baking-pan-conversion) (2026).