🗑️ Garbage Bag Size Calculator
Enter your trash can’s diameter and height to find the flat bag width and length that will actually fit it, with an approximate gallon size.
What this calculator does
The Garbage Bag Size Calculator translates the dimensions of your trash can into the flat bag width and length you should look for on packaging, so you stop guessing between “tall kitchen,” “13 gallon,” or “contractor” bags.
How the formula works
A bag laid flat is half of the can’s circumference wide, so Flat Width = π × Diameter ÷ 2. The bag also needs enough length to cover the bottom of the can (roughly half the diameter) plus the full height, plus a bit of extra overhang so you can gather and tie it: Bag Length = Height + Diameter ÷ 2 + Overhang. The calculator also estimates the can’s approximate volume in gallons, which is the unit most bag packaging is labeled with.
Bag manufacturers vary slightly in how they size and label bags, and bags are typically made a bit larger than the bare minimum to allow for stretch and a comfortable tie — so treat these numbers as a solid starting point rather than an exact spec.