Tool · Free
How much water
your gutters move.
Sioux Falls averages 27 inches of rain a year — and your roof is the biggest catchment surface on your property. Slide the controls below to see annual volume, peak-storm flow rate, and the downspout sizing that matches.
Your roof
Not sure? A 2,000 sqft ranch is about 2,200 sqft of roof. A two-story 2,000 sqft home is about 1,300 sqft of roof.
What your gutters move
Annual
30,202gal
Peak storm
1,902gal/hr
Bathtubs filled / yr
604
Downspouts you need
- 3" × 4" (our default)2 drops
- 2" × 3" (box-store standard)3 drops
A 3×4 downspout moves 2× the water of a 2×3 — that’s why we default to 3×4 on every install. Fewer holes in the gutter trough, fewer clogs.
The why
Why this matters.
Undersized downspouts overflow
A 2×3 downspout handles ~600 sqft of roof in a Sioux Falls storm. Stick a 2×3 on a 1,500 sqft roof and you'll get overflow at every elbow.
Foundation matters
27 inches × 2,000 sqft of roof = ~30,000 gallons routed away from your foundation every year. Skip gutters and that's water at the basement.
We default to 3×4
Most contractors install 2×3 because it's cheaper and matches what's on neighbors' homes. 3×4 is right size for this market. We've been called on enough overflow jobs to know.