What Size Scope Ring do I Need?

by Ryan Cleckner

February 13, 2023



If you’re mounting a scope to rifle, you’re going to need a set of scope rings.

After you’ve determined which style of scope rings you need, you’re going to have to ensure that you get the right size scope rings for your particular scope AND rifle.

So, what size scope rings do you need?

You need scope rings that are the right size for the diameter of your scope tube and also the right height so that your scope fits properly into your rifle.

Scope RIng Size: Diameter

Scope rings are… well… a ring. This circular design is intended to wrap around the main body of the scope (the scope tube) and clamp in place. (for a breakdown of a scopes parts, check out How to Adjust Your Scope)

Scope RIng Sizes
Scope Ring Diameters

Therefore, scope rings must be the right diameter for your scope.

Finding the right size diameter rings is fairly simple once you know which rifle scope you are using: you simply look up the specifications for the scope tube and ensure that you only select rings for that diameter.

For example, if you are using a Vortex Razor Gen II 3-18x scope on your precision rifle (great choice by the way), your scope has a 34mm tube diameter so you need 34mm rings.

Scope RIng Size: Height

Finding the proper height for scope rings isn’t as easy as the diameter.

In order to know the correct scope ring height, you must also have information about the rifle. This is because the scope rings must be tall enough so that the objective lens (the front lens) doesn’t make contact with the barrel and also so that the ocular lens (the lens closest to your eye) doesn’t make contact with the bolt of the rifle.

There are a few ways to find the correct height scope rings:

  1. Ask other shooters/gun store employee
  2. Search on the internet
  3. Use a manufacturer’s chart
  4. Use the GunUniversity Scope Ring Finder.

If you ask other shooters or a gun store employee – be careful! After all, they were likely in your position when selecting the right rings and may have made a poor choice that is going to get passed along to you. Also, this may get you rings that are technically the right size to fit your rifle setup but they may not be the best fit, nor the best rings, nor the best price.

Searching the internet for example of rings that will fit introduces the same problems as above.

Using a manufacturers chart with likely get you close enough but you’re stuck with one style/manufacturer of rings (which may not be what you want) and you still won’t know the best place to find them.

This is why we made the free scope ring calculator.

GU Scope Ring Finder
Scope Ring Finder

Using our free tool allows you to find the correct diameter ring, the correct height ring for your scope and rifle combination, AND it provides a list of ALL rings that will work so that you can choose the correct height for your preferences, the style of ring you’re looking for, AND you can see the best prices and availability online (live)!


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About Ryan Cleckner

Ryan is a former special operations sniper (1/75 Ranger) and current firearms attorney, firearms industry executive, university lecturer, and bestselling author of the Long Range Shooting Handbook.

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