Accurate gutter takeoffs prevent mid-job supply runs and wasted material. This calculator accounts for gutter sections, downspouts, hangers, elbows, sealant, corners, and end caps — everything you need for a complete installation.
K-Style vs. Half-Round Gutters
K-style gutters — most common residential profile, flat back mounts flush to fascia, holds more water per inch, available in 5" and 6" widths
Half-round gutters — traditional U-shaped profile, common on historic homes, requires special brackets, less capacity than K-style at same width
K-style handles ~20% more water volume than half-round at the same width
Sizing for Rainfall
5" K-style — handles up to 5,520 sq ft of roof per downspout in moderate rainfall areas
6" K-style — handles up to 7,960 sq ft, required for steep roofs or high-rainfall regions
Use 6" gutters for roof areas over 1,500 sq ft or regions with 4+ inches/hour rain intensity
When in doubt, upsize — oversized gutters cost only 10–15% more but handle extreme storms
Downspout Placement Rules
Place one downspout every 30–40 linear feet of gutter. Each downspout needs 3 elbows: 2 at the top (to offset from the soffit to the wall) and 1 at the bottom (to direct water away from the foundation). Extend downspouts at least 4 feet from the foundation.
Seamless vs. Sectional
Sectional gutters — sold in 10 ft pieces, seams every 10 ft need sealant, DIY-friendly
Seamless gutters — formed on-site to exact length, no seams = fewer leaks, requires professional equipment
Seamless gutters cost 30–50% more installed but last longer with less maintenance
Gutter quantities locked in?
Build your gutter installation quote in BuildQuotes or jump straight to invoicing.