Custom Aspect Ratio Calculator

Decimal to fraction

Write the decimal as a fraction over a power of ten, then divide by the GCD. 1.85 is 185/100; GCD 5 yields 37:20. 2.39 is 239/100 already coprime.

Cinema 1.85:1 and 2.39:1 are why those two fixtures exist. They are not 16:9 and not 21:9.

Resize with a custom ratio

After 1.85 becomes 37:20, H′ = W × 20/37. The home Resize tab Custom chip does the same math.

Common mistakes

Typing 1,85 with a comma in an en locale. Use a period in v1.

Expecting 2.39 to become 21:9. It will not; the relative error is larger than a 1% default.

Cinema decimals on the Custom Aspect Ratio Calculator

1.85 becomes 37:20 because 185/100 reduces by 5. 2.39 becomes 239:100 because those integers are already coprime. 2.5 becomes 5:2. After the fraction appears you can lock a width and resize with the same H′ = W × rh/rw rule as the home Resize tab.

The 21:9 chip is 2.333…, not 2.39. If a producer says “scope,” type 2.39 here instead of picking ultrawide marketing.

A custom aspect ratio is any shape that is not already a chip. Type the decimal from the brief, read the simplified fraction, then set one side. The other side follows. Use 1.85 or 2.39 for cinema, and the exact pixel pair when a panel is sold under a nickname such as 21:9.

Cinema decimals that are not chips

1.85:1 becomes 37:20. 2.39:1 becomes 239:100. 2.5:1 becomes 5:2. None of those are 16:9 or 21:9. Type the decimal, read the fraction, then resize a width. The home Resize Custom chip runs the same decimalToFraction helper.

Comma decimals such as 1,85 are not parsed in v1 English UI. Use a period. If a panel is 19.5:9, type 19.5 or the exact pixels; do not round it to 2:1 and call it done.

Frequently asked questions