# Contact Ratio Calculation For Spur Gears With Calculators

Contact ratio is a very important parameter for spur gear designs. When all the parameters are calculated for mating spur gears, you need to be also sure about the contact ratio of mating spur gears is inside the acceptable range.

The minimum acceptable contact ratio recommended by spur gear manufacturers is 1.2. In general applications, contact ratios of spur gear systems are around 1.5.

You can use the calculator below to see the contact ratio of your spur gear mates.

## How To Use Contact Ratio Calculator For Spur Gears?

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As you see above, the use of a contact ratio calculator is very simple. You need to have some information about your spur gear mate system;

• Np is the number of teeth at your pinion gear.
• Ng is the number of teeth at your bigger gear.
• Pd is the diametral pitch value of your gear. If you gave the metric module, the value you can convert this metric module into diametral pitch value.
• θ is the pressure angle value of your gear tooth. In most applications, this value is 20 degrees. But you need to take a look at the catalogs of gear manufacturers.

Enter the required data above at the contact ratio calculator, then click on the ‘Calculate!’ button to see the contact ratio.

Also, you can use the MB-Unit Converter tool to convert your units into other unit sets.

If you want to do another calculation, click on the ‘Reset’ button then re-enter the values again.

## Conclusion For Contact Ratio Calculator For Spur Gear Mates

This calculator can be a very good companion for you to use in the phase of spur gear system design.

All the responsibilities of calculations that do with these calculators are on the users.

Do not forget to take a look at the other engineering calculators available in Mechanicalland!

Do not forget to leave your comments and questions about the contact ratio calculator for spur gear mates below.

Your precious feedbacks are very important for us.

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1. Ted says:

The contact ratio didn’t work correctly for a pinion with 16 teeth, gear of 44 teeth, diametral pitch of 6 teeth/in, and 20-degree pressure angle, it should be 1.615. A student of mine used your website and submitted the incorrect answer.

1. MB-Editor says:

Hi Ted. We are very thankful for your feedback. Feedbacks like yours are very important for us. Actually, contact ratio formulations changes according to different types of gear meshes. This calculator is made for the standard spur gear meshes. Your spur gear type is rack and pinion. Could you please check the formulations stated in this topic, for different types of spur gear meshes?

2. Harry says:

Yeh I’m pretty sure this calculator is incorrect. Use the equation on SDP/SI website… completely different result.

1. If you tell us exactly where you got the error, we will fix it. It would be wrong to say that this is wrong.