Gutter calculator
Estimate outputs: Linear length, Whole pieces, Downspouts. Adjust Eave length, Number of gutter runs, Stock piece length to match your project.
Estimate outputs: Linear length, Whole pieces, Downspouts. Adjust Eave length, Number of gutter runs, Stock piece length to match your project.
Inputs and units
Use the units shown beside each field. Replace the sample values with your measurements and the figures on the selected product packaging.
| Parameter | Example input |
|---|---|
| Eave length | 10 m |
| Number of gutter runs | 2 |
| Stock piece length | 3 m |
| Maximum run per downspout | 12 m |
| Waste allowance | 5 % |
Formula and assumptions
Linear lengthEave length × Number of gutter runs × (1 + Waste allowance / 100)
Whole piecesceil(Linear length / Stock piece length)
DownspoutsNumber of gutter runs × ceil(Eave length / Maximum run per downspout)
ceil = round up; floor = round down; max = the greater value. Trigonometric angles are converted from degrees to radians.
Allowance is applied before rounding to whole packages. Whole units are rounded up; displayed decimals are rounded only for readability.
Roof calculations assume a simple rectangular surface or equal pitch slopes. Include overhangs in the entered plan dimensions; check overlaps and effective coverage.
Worked example
Sample values are examples, not product specifications. Run the calculation again with your own measurements.
| Result | Calculation |
|---|---|
| Linear length | 21 m |
| Whole pieces | 7 |
| Downspouts | 2 |
Related calculators
Related tools use separate measurements. Check their inputs before transferring quantities.
These are quantity estimates. Confirm product coverage, site conditions and required dimensions before ordering.