How to Check the Slope of an Existing Gutter
A step-by-step method for measuring the real pitch of a gutter already on your house — and deciding whether it needs adjusting.
Suspect your gutters are draining poorly? Before you re-hang anything, measure what you actually have. It takes five minutes and a level.
What you need
- A long spirit level or a laser level
- A tape measure
- A helper (optional but handy)
Step 1 — Measure the run
Measure horizontally from the high end of the gutter to the centerline of the downspout outlet. Record it in feet.
Step 2 — Measure the drop
Hold the level against the gutter and read how far the downspout end dips below level over that run. Alternatively, compare the height of both ends against a level reference line on the fascia. Record the drop in inches.
Step 3 — Compute the pitch
The realized pitch is just:
Pitch = Drop (in) ÷ Run (ft)
Feed both numbers into Check mode in our calculator and it returns the pitch in inches per foot, the grade as a percentage, and the millimeters-per-meter equivalent — then flags whether the slope falls inside the typical range.
Reading the result
- Within range (1/4″/10 ft to 1/16″/ft): you are good.
- Too shallow: water will pond. Consider re-hanging with more fall.
- Steep: hydraulically fine, occasionally just a cosmetic concern.
If the slope is borderline and the gutter drains cleanly after rain, it is usually fine to leave it. Persistent standing water is the signal to adjust.