Chain Length Calculator

Enter chain specification, sprocket teeth, and center distance to calculate roller chain link count and total length. Per GB1243-1997.

Core Formula: Lp = 2a₀p + (z₁+z₂)/2 + [(z₂−z₁)/(2π)]² / a₀p
mm
teeth
Recommended z₁ ≥ 17
teeth
mm
Recommended: 30P ≤ a ≤ 50P

Results

Center Distance in Pitches a₀p
- pitches
Calculated Link Count Lp
- links
Selected Link Count Lp₀ (even integer)
- links
Total Chain Length L = Lp₀ × P
- mm

Auxiliary

Gear Ratio i = z₂/z₁
-
Recommended Center Distance Range
- mm
Small Sprocket Pitch Dia. d₁
- mm
Large Sprocket Pitch Dia. d₂
- mm

Notes

Link Count Formula

Lp = 2a₀p + (z₁+z₂)/2 + c²/a₀p

where c = (z₂−z₁)/(2π), a₀p = a₀/P

Select nearest even integer ≥ Lp to avoid offset links.

Design Guidelines

  • Use even link counts to avoid transition links
  • Center distance: 30P–50P recommended
  • Max speed ratio generally ≤ 8
  • Min small sprocket teeth ≥ 17 for high speed