Gutter Slope Per Foot

The Gutter Slope Per Foot Calculator exists because the per-foot drop is the most practical unit for marking out a gutter on site. Rather than working back from a total fall once and hoping the string line is right, an installer can step a chalk line foot by foot along the fascia using a constant drop-per-foot figure — making slope visible as a simple progression of marks. This tool converts any slope specification into its per-foot equivalent, then generates the cumulative drop at every foot of the run so you can transfer it directly to the wall without further arithmetic.

The per-foot slope is derived from the core fall relationship:

Drop (in) = Run (ft) × Slope per foot (in/ft)

To find slope per foot from a total drop and run:

Slope per foot = Drop ÷ Run

To convert from a per-10-ft figure (the common US convention) to per-foot, simply divide by 10. For example, the standard minimum of 1/4 in per 10 ft ÷ 10 = 0.025 in/ft. The cumulative drop at any point along the run is just the per-foot slope multiplied by the distance from the high end: at 15 ft with a 0.0625 in/ft slope, the mark is 15 × 0.0625 = 0.9375 in below the high-end level line.

Gutter slope per foot is the vertical drop built in for every single foot of horizontal run. It is the most practical way to mark out a gutter, because you can read the drop at any point along a chalk or string line. The default here, 1/16 in per ft (0.0625 in/ft), is a popular residential slope; the minimum, 1/4 in per 10 ft, works out to just 0.025 in/ft.