Quick calculations for module, teeth and outer diameter, sprocket pitch circle, timing pulley diameter and gear ratio. Enter your measurements and use the result in the quote form.
Enter two of them and we work out the third. On a spur gear the outer diameter = module × (teeth + 2).
Enter at least two values to see a result.
Pick the chain number and the number of teeth; the pitch circle and approximate outer diameter are calculated.
The number of teeth must be at least 6.
Pick the belt profile and the number of teeth; the pulley pitch diameter is calculated.
Enter the number of teeth.
Enter the teeth of the driving and driven gear; the ratio, output speed and torque gain are calculated.
Enter the number of teeth of both gears.
To have a gear made again you need two numbers: the module and the number of teeth. You can count the teeth; the module usually has to be measured. Measure the outer diameter with a caliper, count the teeth, and the first calculator gives you the module.
If the result is an odd number like 1.97, do not worry: a few tenths of a millimetre of measuring error is normal and the nearest standard module (2 here) is the right one. On a worn gear the outer diameter shrinks slightly, so measuring the mating gear is more reliable.
On a sprocket the pitch circle is where the chain rollers sit; it follows from the chain pitch and the number of teeth. On a timing pulley the pitch diameter is the belt pitch times the number of teeth divided by pi, and belt length and centre distance are chosen from that diameter.
The gear ratio is the ratio between the numbers of teeth. The larger it is, the lower the speed and the higher the torque. When designing a drive, the centre distance matters as much as the ratio.
If measuring is difficult, send us a photo of the part and our technical team works out the dimensions for you.
Measure the outer diameter with a caliper, count the teeth and divide the diameter by (teeth + 2). Round the result to the nearest standard module.
Wear reduces the outer diameter, so the result comes out slightly low. Measuring the mating gear, or an undamaged part of the teeth, is more accurate.
Inch gears use diametral pitch instead of module: module = 25.4 / DP. Send us your measurements and we will work out which system it is.
They are enough for a quote. Before production our technical team checks them against your sample, photo or drawing.
Quotes are free. We reply with price and lead time within 48 hours.
Cookies. We use cookies that are necessary for the site to work. With your permission we also use additional cookies to measure visits (analytics) and see the effect of our ads (marketing). Cookie policy