Roller Chain Wear & Elongation Calculator

General industrial practice (per ANSI B29.1-aligned maker guidance): 1.5% elongation for typical drives, 1.0% where sprockets exceed ~68 teeth or centres are fixed (no tensioner travel), and as low as 0.5% for precision timing applications. Beyond ~2% the chain damages sprockets and skipping risk rises sharply. Measure under light tension — slack chain measurement understates wear.

As many as practical — measurement error divides by the span: over 24 pitches of 19.05 mm chain, 1% elongation is 4.6 mm (easily read on a vernier), while over 6 pitches it's barely a millimetre. Industry tools standardise on 12–48 pitch spans. Measure pin-centre to pin-centre, same side of both pins (or inside-inside plus one pin diameter), chain tensioned and on a flat or wrapped on the sprocket.

Dramatically — elongation IS the wear of pin-bushing joints that lubrication protects: properly lubricated drives commonly achieve 5–10× the life of run-dry chain, and the difference is visible in this calculator within months. The right method ranks: continuous (drip/bath/spray) beats periodic brushing beats nothing; apply to the slack span's link plate gaps where centrifugal force carries oil into the joints, not onto the rollers' outside.

Uneven elongation usually means uneven lubrication or a damaged section: joints that ran dry (outer chain on a vertical loop, sections missed by a clogged drip), a kinked/bound link working harder, or corrosion pitting on one stretch. Measure 3–4 sections around the loop and use the worst; a single bad section in an otherwise healthy chain can sometimes be replaced (with a matching-wear used section, not new) but full replacement is the defensible call near the limit.