Gutter Pitch Calculator

The Gutter Pitch Calculator exists to measure, verify, and design the slope of a rain gutter in the unit most familiar to US and Canadian installers: inches per foot. Gutter pitch is a gentle drainage gradient — a tiny fraction of an inch for every foot of run — that keeps water moving to the downspout instead of pooling in the channel. Without a way to quantify that slope quickly, installers either guess (risking flat spots) or over-slope (making gutters look visibly tilted). This tool solves pitch from a measured run and drop, designs the drop for a chosen pitch, finds the maximum run a given drop supports, and flags whether the result sits inside the practical drainage range.

Gutter pitch is calculated from the run and the vertical drop:

Pitch (in/ft) = Drop (in) ÷ Run (ft)

Reversing the formula gives the other two common modes:

Drop (in) = Run (ft) × Pitch (in/ft)  ·  Run (ft) = Drop (in) ÷ Pitch (in/ft)

For example, a gutter that falls 1 inch over a 20 ft run has a pitch of 1 ÷ 20 = 0.05 in/ft (½ in per 10 ft). To design a new 30 ft run at the 1/16 in/ft standard: 30 × 0.0625 = 1.875 in of total drop needed. Grade percentage and 1:X ratio are derived from the same pitch value: grade% = pitch × (100 ÷ 12), ratio = 1 : (12 ÷ pitch).

The gutter pitch calculator opens on Check pitch because the most common question is "what pitch does my gutter actually have?" Enter the run and the height drop and it returns the pitch as inches per foot, a grade percentage, a 1:X ratio and an angle, then tells you whether it falls inside the typical drainage band. Switch to Drop to design a new run from a chosen pitch, or Max run to see how far a pitch will carry a given drop.

Prefer to think in drop per foot rather than pitch? The gutter slope per foot tool focuses on that, and the slope angle tool converts any pitch to degrees.