Understanding your result
The headline is the number of hangers. The stats give the hangers per run, the fasteners and the boxes. The breakdown shows the spacing, the average run, the count per run with the end hanger and the totals.
The number to remember is the spacing: it is what keeps a gutter level under load, and it is the one number to give an installer. The gutter length comes from the gutter length calculator; the slope the hangers set comes from the gutter slope calculator; and guards from the gutter guard calculator.
How we calculate this
The plus one per run puts a hanger at both ends, which is where gutters sag first. The calculator divides the total length evenly between the runs; for runs of very different lengths, the total comes out within a hanger or two of counting each run separately.
The assumptions behind the numbers
| Assumption | Default | Where it comes from |
|---|---|---|
| Spacing without heavy snow | 30 in (24 to 36 in) | Gutter manufacturers’ installation guides |
| Spacing in snow and ice | 18 in (18 to 24 in) | Gutter manufacturers’ guides for snow regions |
| Hangers per box | 10 | Common packaging (10, 25, 50) |
| Fasteners | 1 per hidden hanger or spike, 2 per bracket or strap | Product instructions |
Assumptions last reviewed October 7, 2026.
The calculator does not count the extra hangers at outlets and corners beyond the ends, and it does not check the fascia’s condition. The downspout placement guide covers where the outlets go.
Two worked examples
A gable house without heavy snow
80 feet of gutter in two runs, 30-inch spacing, hidden hangers, boxes of 10.
- Per run: 480 ÷ 30 + 1 = 17
- Hangers: 34; screws: 34; boxes: 4
Four boxes, six hangers spare for the outlets.
A hip house in snow country with fascia brackets
140 feet of gutter in four runs, 18-inch spacing, fascia brackets, boxes of 25.
- Per run: 35 ft = 420 in ÷ 18 = 23.3, so 24 + 1 = 25
- Hangers: 100; screws: 200; boxes: 4
A hundred brackets: close spacing is what keeps an ice-filled gutter on the house.
Where to find your inputs
Gutter length and runs. From the gutter length calculator.
Climate. Whether the gutter carries snow and ice in winter.
Hanger type. From the product; hidden hangers are the common choice.
Common mistakes
- Wide spacing in snow. An ice-filled gutter is heavy; 18 to 24 inches.
- Fastening only into the fascia. Reach the rafter tails or sub-fascia.
- No end hangers. Ends sag first.
- Reusing spikes. They loosen again. Switch to screws.
- Hangers that block the slope. Set them along a chalk line at the planned slope.
- Forgetting the outlets. A hanger each side of every outlet.
Questions people ask
- How far apart should gutter hangers be?
- Every 24 to 36 inches in areas without heavy snow, and every 18 to 24 inches where snow and ice load the gutter. Most installers use 24 inches as a safe all-round figure. Add a hanger within about 6 inches of each end, corner and outlet.
- How many gutter hangers for 80 feet of gutter?
- At 30-inch spacing, 80 feet in two 40-foot runs takes 17 hangers per run (480 ÷ 30 + 1), 34 in all. At 18 inches for snow country it is 28 per run, 56 in all.
- What type of gutter hanger is best?
- Hidden hangers screwed through the gutter into the rafter tails or sub-fascia hold the most weight and do not show. Fascia brackets under the gutter are strong but visible; roof straps go under the shingles (best done when reroofing); spikes and ferrules are the old method and loosen with freeze-thaw.
- How long should gutter hanger screws be?
- Long enough to pass through the gutter, the fascia and 1½ to 2 inches into solid wood, usually a rafter tail or sub-fascia: hidden hangers come with 1½ to 2 inch screws. A screw only in a thin fascia board pulls out under load.
- Why are my gutters sagging?
- Hangers too far apart, spikes loosened by freeze-thaw, fasteners only in rotten fascia, or a gutter full of debris or ice. Re-hanging at closer spacing with hidden hangers into the rafter tails is the usual fix.
- Do gutter guards change the hanger spacing?
- Not usually, but guards that attach to the hangers or the front lip need a hanger at each guard joint, and guards add a little weight. Keep to the climate spacing.