Bin Bag Size Calculator
Measure your bin and find the minimum flat width and length your liner needs. Works for round, square and rectangular bins.
How to measure your bin for a liner
Use the internal measurements of the bin, not the external casing. Measure at the widest point so the liner can pass over the rim without stretching.
Measure the opening
For a round bin, measure the diameter. For a rectangular bin, measure both width and depth.
Measure the height
Measure vertically from the inside base to the top edge of the bin.
Allow for the base and rim
The calculator adds material to cover the bin base plus your selected fold-over allowance.
Methodology and formulas
How the bin bag calculation works
Bin bags are normally sold by their flat width and total length. The correct size depends on the shape of the opening and the material needed to cover the bottom—not only the bin's litre capacity.
Round bin width
Diameter × 3.14 ÷ 2Rectangular bin width
Inside width + inside depthRound bag length
Bin height + half the diameter + overhangRectangular bag length
Bin height + half the base diagonal + overhangResults are rounded up to the next whole centimetre or inch. Because seams, gussets and manufacturer tolerances vary, check the stated product dimensions before ordering.
Methodology last reviewed: .
Worked example
A round kitchen bin measuring 40 cm across and 60 cm high, with 10 cm of overhang:
- Flat width
- 40 × 3.14 ÷ 2 = 63 cm
- Bag length
- 60 + 20 + 10 = 90 cm
- Minimum liner
- 63 × 90 cm
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Cleaning companies, facilities teams, bin suppliers and waste-management guides can embed this tool free of charge. Help readers calculate the minimum flat liner width and length from real bin measurements without leaving your page. The attribution beneath it is appreciated and can be removed if editorial policy requires it.
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Bin bag size questions
How do I know what size bin bag I need?
Measure the inside of the bin at its widest points. For a round bin, measure the diameter and height. For a square or rectangular bin, measure the width, depth and height. The calculator converts those measurements into the minimum flat bag width and length.
Is the litre size enough to choose a bin liner?
No. Litre capacity is useful for comparison, but bins with the same capacity can have different shapes. Match the calculated flat width and bag length first, then use litres as a secondary guide.
How much overhang should a bin liner have?
A 10 cm overhang is a practical starting point for folding the liner over the rim. Increase it if you need additional material for tying, or reduce it when the bin has a liner retaining ring.
What size bin bag fits a 50 litre bin?
There is no single answer based on litres alone because tall, round and rectangular 50 litre bins have different openings. Measure the bin dimensions and choose a liner whose flat width and length meet or exceed the calculated minimums.
Should I choose a larger bag if my exact size is unavailable?
Yes. Choose the next available liner with both a flat width and length at least as large as the calculated result. A smaller liner may split, slip into the bin or fail to cover the base.
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