What this tool answers
You need a first-pass telescoping ladder length before buying. Enter the height to the top support or landing in feet. The calculator names the smallest class — 13, 17, or 20.5 ft — that clears support height plus 3 ft, or returns NO_MATCH. It is not an A-frame standing-height chart, structural check, or fall-protection plan.
Why add 3 feet
When a ladder is used to access a landing, common guidance expects the side rails to extend about 3 feet above that landing so you can step off safely. This site uses that as a transparent shopping rule for straight-extension mode and states its limits.
Class ladder on this site
Classes use published VEVOR US telescoping A-frame max lengths checked 2026-09-10: 13 ft, 17 ft, and 20.5 ft. Matching rule: smallest class where class.maxLen ≥ support_height_ft + 3.
When the answer is NO_MATCH
If needed length exceeds 20.5 ft, this site returns NO_MATCH. Typical next steps: re-measure support height, use a longer extension ladder, or choose another access method. Do not force a 20.5 ft consumer unit past this screen.
Load, angle, and top steps
Confirm the live load rating (often 330 lb). Set a safe angle on firm level ground. Keep three points of contact. Never stand on the top steps or overload the ladder.
Sources
VEVOR US telescoping ladder product pages for max length claims dated in products.json (checked 2026-09-10). Shopping heuristic: support height + 3 ft for straight extension. Safety framing: load, angle, three points of contact, no top-step standing.