Gutter lengths Calculator: measuring notes and method
Measure each gutter run
Record the lengths at the actual gutter position, then list the available stock lengths. Do not use the roof perimeter unless every edge has guttering.
Check continuous lengths
The result pools reusable offcuts. A long uninterrupted gutter run or a specified lap joint may require more stock than simple total-length division suggests.
Formula
Required length = length per run × runs × (1 + waste ÷ 100). Stock count = required length ÷ stock length, rounded up.
Worked examples in metric and imperial units
Illustrative values match Reset example and stay fixed when you edit the calculator. Both columns describe the same calculation; converted inputs are rounded.
Metric worked example
- Required length per run
- 6 m
- Quantity
- 1
- Stock length
- 3 m
- Waste allowance
- 10 %
Stock lengths to buy: 3
Imperial worked example
- Required length per run
- 19.685 ft
- Quantity
- 1
- Stock length
- 9.8425 ft
- Waste allowance
- 10 %
Stock lengths to buy: 3
Follow the calculation
Lengths in this working are in metres.
- Net required length = 6 × 1 = 6 m.
- Stock count = 6 × 1.1 ÷ 3, rounded up. This assumes usable offcuts.
Reviewed 19 October 2026. How calculations are checked · Report a correction
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