Chain Center-to-Center

Roller-chain center distance — solve for distance from links, or links from a target distance.

C = (P/8)·[(2L − N₁ − N₂) + √((2L − N₁ − N₂)² − (8/π²)(N₂ − N₁)²)]

Solve for

Chain

Sprocket 1 teeth (N₁)

Sprocket 2 teeth (N₂)

Chain length (links)

7.368 in / 187.15 mm

Notes

25# pitch is 0.250 in, 35# is 0.375 in. Result is shown in both inches and mm.
Chain length is in pitches (links). Solving for length rounds up to the next even number of links — roller chain needs an even count to close without an offset link.
Assumes a two-sprocket drive on a common plane, no idlers.