What you need
- A 25-foot tape measure
- Paper and a pen — or your phone's camera and notes app
- About 30 minutes and a dry day
The five steps
- 1
Sketch the roofline from the ground
Walk the outside of the house and draw a rough overhead outline — it does not need to be to scale. Mark every edge where a roof plane ends in a horizontal line, because that is where gutter goes. Sloped edges (the diagonal edge of a gable) do not take gutter.
Give each straight run a letter. You will measure and record them one at a time, and the letters stop you double-counting a corner.
- 2
Measure each run at ground level
Run a tape along the ground directly under each roof edge, from corner to corner, and round up to the next whole foot. Gutter is cut to length on site, so a few inches either way costs nothing — a missed run costs a return trip.
You do not need to be on a ladder for any of this, and you should not be. Measuring from the ground is accurate enough for planning and it is the reason this guide exists.
- 3
Count the corners
Note every inside corner (where two runs meet pointing into the house, like around a bay) and every outside corner (where they wrap around a projection). These become mitres, they are priced separately from straight footage, and they are the single most common thing homeowners leave off.
- 4
Count and measure the downspouts
Note where each existing downspout drops, and measure the height from the gutter to the ground at that point — eave height, roughly, which you can estimate from a storey count if you cannot reach: about 10 feet for a single storey, about 20 for two.
If you are planning new ones, our gutter size calculator works out the minimum number your roof needs for the rainfall where you live.
- 5
Note the roof pitch and the obstacles
Pitch changes the size of gutter you need. You can estimate it from the ground: a roof you could comfortably walk on is shallow (3-in-12 to 5-in-12), one that clearly could not be walked is steep (8-in-12 and up).
Then note anything that will affect the work: two-storey sections, roof valleys that dump into one spot, a porch roof draining onto a lower roof, overhanging trees, and any fascia board that already looks soft or stained. Every one of those changes the quote, and every one is better known before the crew arrives.
Six mistakes that blow the numbers
| The mistake | What to do instead |
|---|---|
| Measuring the sloped edge of a gable | Only horizontal roof edges take gutter. A gable's diagonal edge takes none. |
| Measuring the walls instead of the roof | The roof overhangs the wall. Measure under the drip edge, not along the siding. |
| Forgetting the garage, porch or dormers | Every separate roof plane with a horizontal edge needs its own run. |
| Leaving out corners and mitres | Corners are priced separately. Count inside and outside corners as you go. |
| Guessing the downspout drop height | A two-storey drop is roughly double the material and a different install. Estimate by storey if you can't measure. |
| Getting on the roof to check | Nothing in this list requires a ladder. Falls from height are the real risk in gutter work — that is our job, not yours. |
Measurement worksheet
Print this and fill it in as you walk the house.
| Run | Where on the house | Length (ft) | Corners | Downspouts |
|---|---|---|---|---|
| A | ||||
| B | ||||
| C | ||||
| D | ||||
| E | ||||
| F | ||||
| G | ||||
| H |
- Total feet of gutter
- Total inside + outside corners
- Total downspouts
- Approx. eave height (single / two storey)
- Roof pitch (walkable, or steep)
- Trees overhanging the roof? (Y / N)
- Any soft or stained fascia? (where)
- Anything else we should know