Roller Chain Calculator
This roller chain calculator finds the chain length in links for two sprockets at a set center distance, then the exact center distance for that chain. Pick the ANSI chain size, enter the sprocket teeth and center distance, and the roller chain calculator returns the links, the chain length in inches and feet, the speed ratio, the sprocket pitch diameters, and the chain speed.
Results
The Roller Chain Calculator is part of our Machinery collection. Browse more machinery to size, convert, and check your work alongside this tool.
What the roller chain calculator does
A roller chain is sold by the link, and it should have an even number of links so the two ends join without an offset link. The roller chain calculator works out the length in pitches from the sprocket sizes and center distance, rounds up to the next even number, and then solves for the center distance that chain gives. Set the sprockets there, or plan an idler or adjustment for tension.
Chain length formula
With p the pitch, C the center distance, and N1, N2 the teeth:
The result is rounded up to an even number of links, and the center distance is solved back from that length.
Roller chain calculator example
#40 chain (1/2 in pitch), 15 and 30 tooth sprockets, 20 in centers, driver at 1,200 RPM:
The chain is 52 in long, the ratio 2:1, the output speed 600 RPM, and the chain speed 750 ft/min. Pitch diameters are 2.405 and 4.783 in.
How to use the roller chain calculator
Choose the ANSI chain number; the pitch in inches is the chain number divided by 80, so #40 is 1/2 in. Enter the teeth on the driver and driven sprockets and the center distance in inches. Add the driver speed to see the output speed and chain speed. Press Calculate and order the chain by the number of links shown.
Reading the chain length calculator result
Order the chain by size and link count, such as #40 × 104 links. The adjusted center distance is where the shafts should sit for that chain with normal sag; leave adjustment of about one pitch for wear. Chain speed affects lubrication: drives under a few hundred ft/min can be oiled by hand, while faster drives need drip, bath, or pump lubrication. Small driver sprockets wear chain faster, so 17 teeth or more is a common minimum for smooth running.
When to use a chain and sprocket calculator
- Replacing a chain on a conveyor or machine
- Designing a new sprocket drive
- Changing a drive ratio with new sprockets
- Checking chain speed for lubrication
- Planning go-kart and equipment drives
Common roller chain calculator mistakes
- Using an odd number of links. Round up to an even count.
- Using outside sprocket diameter. The formula uses pitch.
- No adjustment for wear. Chain stretches with use.
- Too small a driver sprocket. Small sprockets wear chain fast.
Tips for roller chain sizes and fit
- Keep the slack side on the bottom where possible.
- Align sprockets with a straight edge.
- Replace sprockets and chain together when both are worn.
Chain center distance calculator and slack
Chain drives run best with a little slack on the return side, roughly 2% of the span for horizontal drives. Too tight and the chain and bearings wear quickly; too loose and the chain whips or jumps teeth. Because chain comes in whole pitches, an exact center distance is rare, so designs include an adjustable motor base, a slotted bearing mount, or an idler sprocket on the slack side. A center distance of 30 to 50 pitches is a common design target. Shaft loads from the chain pull feed the bearing choice, which the bearing life calculator checks.
Roller chain sizes and chain speed
Larger chain carries more power at low speed, while smaller chain on more teeth runs smoother and quieter at high speed. Chain speed in ft/min equals pitch × teeth × RPM ÷ 12, so 750 ft/min in the example. Multi strand chain multiplies capacity without a larger pitch. For a quieter drive with no lubrication, compare a toothed belt with the timing belt calculator.
Sprocket pitch diameter chart for #40 chain
Pitch diameter = 0.5 ÷ sin(180° ÷ N) for 1/2 in pitch chain:
| Teeth | Pitch diameter (in) |
|---|---|
| 12 | 1.932 |
| 15 | 2.405 |
| 18 | 2.879 |
| 20 | 3.196 |
| 24 | 3.831 |
| 30 | 4.783 |
| 36 | 5.737 |
Roller Chain Calculator FAQ
How do you calculate roller chain length?
Use L = 2C/p + (N1 + N2)/2 + (N2 − N1)² ÷ (4π² C/p), with C the center distance and p the pitch, then round up to an even number of links.
Why an even number of links?
Roller chain alternates inner and outer links, so an even count joins with a standard connecting link. An odd count needs an offset link, which is weaker.
What pitch is #40 chain?
ANSI chain pitch in inches is the chain number divided by 80: #40 is 1/2 in, #50 is 5/8 in, and #60 is 3/4 in.
How do I find the sprocket ratio?
Divide the driven teeth by the driver teeth. 30 over 15 is 2:1, so the output turns at half the input speed.