Diameters
in- Pitch diameterDp
- 3.196
- Outside diameter (turned)De
- 3.457
- Standard OD min / max
- 3.344 – 3.509
- Bottom diameterDf
- 2.884
- Tooth angle
- 18.00°
Design & calculation
Roller chain sprocket calculator
Pick the chain standard, the pitch and the number of teeth: get every dimension you need to make or check the sprocket.
- Standard formulasANSI B29.1 and ISO 606 / DIN 8187
- Inch and mmSimplex, duplex and triplex
- Built for the shopInspection, hub, stock size and DXF
Chain parameters
Pick the chain and the number of teeth to calculate the sprocket.
1 Chain standardANSI (A series) is the American chain. ISO/DIN B series is the European chain. Same pitch, different roller and width.
Strands
Units
Sprocket preview
- Chain
- ANSI 40
- Pitch
- 0.500 in
- Roller Ø
- 0.312 in
- Inner width
- 0.309 in
ISO 606 tooth form with true arcs, in mm, ready for plasma, laser, waterjet or CAD. Includes a 15 mm bore.
Sprocket 1/2" x 5/16" · N20
ANSI B29.1 · ANSI 40 (08A)
Inspection
in- Caliper diameter (even N = bottom dia.)Mc
- 2.884
- Measurement over pins Ø 0.312MR
- 3.508
Even N: measure root to root across opposite teeth.
Tooth width
in- Tooth width (per strand)bf1
- 0.287
- Tooth side chamferba
- 0.065
- Tooth side radiusrx
- 0.500
Tooth form (ISO 606)
in- Roller seating radiusri
- 0.157 – 0.163
- Tooth flank radiusre
- 0.823 – 1.447
- Roller seating angleα
- 115.50° – 135.50°
Hub
in- Max hub diameterDg máx
- 2.633
Stock material (steel)
- Cut Ø (bar or plate)
- 3.575 in
- Cut length / thickness
- 1.299 in
- Stock weight
- 1.68 kg
- Approx. finished weight
- 0.81 kg
Density 7.85 kg/dm³. Finished weight is approximate (useful for freight or heat-treat quotes).
Dimensions calculated with the ISO 606 and ANSI B29.1 formulas. Check against the actual chain before manufacturing; manufacturers may use their own tolerances.
How many links does the chain need?Get the chain length, the exact center distance, the ratio and the RPM of your drive.
Chain length calculator →From the shop floor
Real parts made in a machine shop
Custom sprockets, shafts and gears: from the calculation to the lathe and the machining center.
Frequently asked questions
What is the difference between ANSI and ISO (European) roller chain?
For the same pitch, the roller and the inner width change. At 1/2" pitch, ANSI 40 has a 0.312" (7.92 mm) roller while the European 08B has 0.335" (8.51 mm). That is why the bottom diameter and tooth width differ: a sprocket cut for one does not always run well with the other.
How is the sprocket pitch diameter calculated?
PD = pitch ÷ sin(180° ÷ N). It is the circle on which the chain roller centers sit.
How do I measure a sprocket with an odd number of teeth?
With an odd tooth count no two teeth are opposite, so a caliper does not read the bottom diameter directly. The calculator gives the corrected caliper diameter: PD · cos(90° ÷ N) − roller Ø.
Does it work for plate wheels without a hub?
Yes: untick “Sprocket with hub” and the calculator uses the tooth width for stock size and weight.