Gutter and downpipe calculator: how many downpipes do I need?
Enter your roof size and pitch to check how many downpipes your gutter needs, then get a full parts list.
Roof pitch
Gutter profile
Where do the outlets go?
Effective roof area
60.0 m²
Rain to carry
1.25 l/s
Each outlet takes
37 m²
Downpipes needed
2
Shopping list
3 x Half Round Gutter 112mm x 4m
2 x Gutter Union Bracket
2 x Gutter Bracket (pack 10)
2 x Gutter Stop End
2 x Gutter Running Outlet
4 x Downpipe 68mm x 2.5m
8 x Downpipe Clip 68mm
2 x Downpipe Shoe 68mm
Sized to Approved Document H (75mm/h rain, level gutter): this profile is treated as a 100mm gutter with a 63mm outlet. Brackets about every 0.9m, downpipe clips about every 1.8m. Check the manufacturer's own flow table for valley gutters, bends or long runs.
How it works
1Measure the eaves length and the roof depth on plan.
2Pick the roof pitch and gutter profile.
3Choose whether outlets sit at the ends or along the run.
Take your quantities across to Price Planter and compare them across UK builders' merchants — including whether splitting the order across two merchants works out cheaper.