Garbage Bag Size Calculator

Enter your trash can's dimensions — width, depth, and height — along with its shape (rectangular or cylindrical) and preferred overhang, and the Garbage Bag Size Calculator tells you exactly what bag width and bag height you need. No more guessing at the store or ending up with a bag that slips into the can or barely reaches the rim. Also try the calculate Estimated Cleaning Cost, Low Estimate & High Estimate — House Cleaning Cost.

Trash Can Shape *

Choose the shape that matches your bin.

Unit of Measurement *

Longest side of the bin opening (rectangular only).

Shorter side of the bin opening, or diameter for round bins.

Extra bag length to drape over the rim. Typically 3–6 in (7–15 cm).

Results

Recommended Bag Height

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Recommended Bag Width

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Approximate Bag Volume

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Dimensions Unit

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Frequently Asked Questions

How do I calculate what garbage bag size I need?

For a rectangular bin, the bag width equals the bin's length plus its width (Gw = Tl + Tw). The bag height equals the bin's height plus the overhang plus one quarter of the bag width (Gh = Th + Go + Gw/4). For a round bin, the bag width equals the diameter times π divided by 2. These formulas ensure the bag covers the bin floor, reaches the rim, and hangs over the edge securely. See also our Air Conditioner BTU Calculator.

What garbage bag size do I need for an 8" × 12" × 22" bin?

Using the rectangular formula: bag width = 8 + 12 = 20 inches. Bag height = 22 + 4 (overhang) + 20/4 = 31 inches. So you'd look for a bag approximately 20" W × 31" H. A standard 13-gallon kitchen bag (24" × 27") may work for smaller bins, but a 33-gallon bag would be a closer match for this size.

What are the largest sizes of garbage bags available?

Heavy-duty industrial or contractor bags can reach 60" × 68" and hold up to 95 gallons. These are designed for large drums, construction debris, or yard waste. For home use, the largest commonly stocked size is typically 55 gallons (36" × 58").

What sizes do garbage bags commonly come in?

Standard retail sizes include 4-gallon (small bathroom bins), 8-gallon, 13-gallon (kitchen), 20-gallon, 30-gallon, 33-gallon, 39-gallon, and 55-gallon (large outdoor or commercial bins). Industrial sizes extend to 65 and 95 gallons. Matching the gallon capacity of the bag to your bin's volume helps ensure a proper fit. You might also find our use the Balloon Arch Calculator useful.

How much overhang should a garbage bag have?

An overhang of 3 to 6 inches (7 to 15 cm) is generally recommended. Smaller bins like desk or bathroom cans do well with 3 inches of overhang, while large kitchen or outdoor bins benefit from 5–6 inches to stay securely in place and resist being pulled into the can when filled.

Does the shape of my trash can affect which bag I need?

Yes. Rectangular and square bins use a length-plus-width formula for bag width, while cylindrical bins require the diameter multiplied by π/2. Using the wrong shape formula can result in a bag that's too tight at the base or too loose at the rim. This calculator handles both shapes automatically.

Can I use a slightly larger bag than the recommended size?

Yes — going one size up is generally fine and gives you extra room to tie the bag off. However, an excessively oversized bag will bunch up at the bottom, which can trap liquids and create odors. Aim for a bag no more than 10–15% larger than the calculated dimensions.

How do I convert garbage bag dimensions to gallons?

Multiply the bag width (in inches) by itself, then by the bag height, and divide by 231 to get a rough gallon estimate for a rectangular bag. For cylindrical estimates, use the formula V = π × r² × h / 231. Keep in mind that bag manufacturers measure capacity based on filled volume, so the listed gallon rating may differ slightly from purely geometric calculations.