Chain Length & Center Distance Calculator
Compute roller chain length in links, exact center distance, sprocket pitch diameters, wrap angles, chain speed, and sag recommendations for any ANSI/ISO chain drive.
ANSI & ISO chain sizes
2-mode calculation
Wrap angle check
Sag & tension
Free to use
Calculation Mode
Chain & Sprocket
Selects pitch automatically
Override or enter custom pitch
Multi-strand for higher load
Small / driving sprocket
Large / output sprocket
Input shaft speed
Shaft center-to-center distance
Recommended: 1.5–3% of center distance
Primary Results
Chain Links
—
Press Calculate
Center Distance
—
—
Velocity Ratio
—
—
Chain Speed
—
—
Live Drive Diagram
Drive Analysis
Chain Length
—
mm total
Output Speed
—
rpm driven shaft
Sag Allowance
—
mm recommended
Span — Tight Side
—
mm tangent length
Span — Slack Side
—
mm tangent length
C/p Ratio
—
Recommended 30–50
Wrap Angle & Engagement
Driver Sprocket (N₁) Wrap
—
Min recommended: 120°
Driven Sprocket (N₂) Wrap
—
Larger sprocket always higher
Sprocket Geometry
Driver PD (d₁)
—
—
Driven PD (d₂)
—
—
Driver OD
—
—
Driven OD
—
—
ANSI Chain Size Reference
| ANSI # | Pitch (mm) | Pitch (in) | Roller ø (mm) | Plate Ht (mm) | Min Break (kN) Simplex | Weight (kg/m) | Speed Limit (m/s) | Notes |
|---|
Formula Reference
L = 2C/p + (N₁+N₂)/2 + K²·p/CChain length in links
K = (N₂−N₁) / (2π)Tooth count correction factor
C = p/8 × [L−(N₂+N₁)/2 + √D]Center distance from links
D = [L−(N₂+N₁)/2]² − 8K²Discriminant for C formula
PD = p / sin(180°/N)Sprocket pitch diameter
v = p×N₁×n / 60000Chain speed (m/s), n in RPM
θ1 = 180°−2×arcsin((d₂−d₁)/(2C))Small sprocket wrap angle
Sag = 2–3% × CRecommended slack span sag
Common Questions
How do you calculate roller chain length?
Chain length in links: L = 2C/p + (N₁+N₂)/2 + ((N₂−N₁)/(2π))² × (p/C), where C is center distance, p is chain pitch, N₁ and N₂ are the small and large sprocket tooth counts. Always round up to the nearest even number of links to allow a standard connecting link. An odd number of links requires an offset link, which reduces chain fatigue life.
What is the recommended center distance for a chain drive?
The recommended center distance is 30 to 50 times the chain pitch (30p to 50p). The minimum must clear both sprocket outside diameters. The maximum should keep the wrap angle on the small sprocket above 120° and ideally above 150°. A starting value of 40p is typical for most industrial drives. Very long center distances require chain take-up provisions to compensate for wear elongation.
Why should chain length be an even number of links?
An even link count allows a standard connecting link (master link) to join the ends. An odd link count requires an offset link, which introduces asymmetry in the side plates and reduces the chain’s fatigue strength by approximately 20%. For high-load or high-cycle applications, always design the center distance so an even number of links fits without requiring an offset link.
What is chain sag and why does it matter?
Chain sag is the natural droop in the slack (loose) span. A sag of 1.5–3% of center distance is optimal. Too little sag means the chain is overtensioned — this overloads bearings and increases wear. Too much sag causes vibration, noise, and risk of chain jumping off the sprocket. Vertical drives should have near-zero sag, while horizontal drives benefit from a small sag to absorb shock loads.
What does wrap angle affect in a chain drive?
Wrap angle determines how many teeth are engaged with the chain at any moment. A small sprocket wrap below 120° means fewer than 7 teeth engaged, increasing the load per tooth and risk of skipping. Below 90° the drive is unreliable. For high-torque drives, maintain wrap ≥ 150° on the small sprocket. Increasing center distance or using a larger small sprocket both improve wrap angle.