Chain Drive Length & Links
Roller chain length in pitches and links for two sprockets at a centre distance, rounded to whole links, the centre distance that chain gives, and speed.
Length in pitches, the link count (even by default, with an offset-link note otherwise), the adjusted centre distance, sprocket pitch and outside diameters, wrap on the small sprocket and chain speed.
Example: 12.7 mm pitch, 17 and 45 teeth at 500 mm: 110.24 pitches → 112 links (1,422 mm), which sets the centres at 511.2 mm; ratio 2.65, pitch diameters 69.1 and 182.1 mm, 4.3 m/s at 1,200 rpm.
Whole links,
and the centres they set.
The chain length formula, the rounding to links, and why the centre distance moves.
Length
A chain wrapping two sprockets is two straight runs plus two half-wraps, corrected for the different sprocket sizes: L = 2C/p + (N₁ + N₂)/2 + (N₂ − N₁)²·p/(4π²C) in pitches. The last term is small unless the sprockets differ a lot at a short centre distance.
Links and centres
A chain comes in whole links — an even count avoids an offset (cranked) link — so the length is rounded up and the centre distance recomputed from that count with the inverse formula. The difference is what a tensioner, slotted mount or idler must absorb, along with wear. Pitch diameter is p ÷ sin(180°/N); the outside diameter shown is the usual approximation D + p(1 − 1.6/N).
Not included
Which chain (pitch, strands) suits a power and speed, service factors, lubrication and the wrap needed for tooth loading come from the chain maker’s selection tables — none is embedded. Chain speed = pitch × driver teeth × rpm. Nothing leaves the browser; the same four anonymous usage counts as the rest of the site apply.
SOURCES
- L = 2C/p + (N₁+N₂)/2 + (N₂−N₁)²·p/(4π²C); C from the rounded link count by the inverse formula; pitch diameter p ÷ sin(180°/N); outside ≈ D + p(1 − 1.6/N) — selection tables are the maker’s
Last reviewed 21 September 2026. How results are checked: How we verify.