One thing most people ask when getting a scope is how to measure sight height. After all, a wrongfully mounted scope affects your comfort when shooting a gun.
Before you go out and regret not getting it correct, keep reading to learn how to measure sight height, and use the calculator below to help you find the right settings.
For more on scopes see our write up on the best muzzleloader scope money can buy.
- The correct sight height measurement will help you remain comfortable as you shoot.
- Sight height or height over bore is the distance between the center of the bore and the center of the scope.
- The right height scope is between 1.5 to 1.8″.
Formula for Measuring Scope Sight Height
Here’s a simple formula for calculating sight height:
Sight Height or Height Over Bore Calculator
Here is a simple sight height calculator you can use:
How to Measure Sight Height
Now that you’ve got the calculator, I’ll walk you through the steps on how to measure sight height.
Step 1: Find the center of the bore
You’ll first need to measure your barrel’s diameter and then divide it by two. Keep in mind that the barrel diameter you take is directly beneath the objective bell. To ensure you get an accurate figure, remove the stock.
Let’s assume you measure, and the barrel diameter is 0.814. Then your center of bore will be 0.407. Here is a good example:
Barrel diameter / 2 = center of bore
0.814″/ 2 = 0.407″
Step 2: Find the center of the scope
Next, you’ll need to measure the objective bell diameter and divide it by two. The objective lens is the front part of your scope. Let’s assume you measure and get 1.972″. Then the center of the scope will be 0.986″. Here is the simple formula:
Objective bell diameter / 2 = center of scope
1.972″ / 2 = 0.986″
Step 3: Measure the gap between the scope and barrel
Now measure the gap between the bottom of your scope and the top of the barrel. This should be the same spot you took for the barrel diameter in our first step to ensure we get an accurate number. In this instance, let’s say we get a figure like 0.400″, hold on to that figure.
Step 4: Add it all up
Now that we have all these figures, the last step is adding everything up to get sight height. So, this is what it will be:
Center of bore + center of scope + gap between = sight height
0.407″ + 0.986″ + 0.400″ = 1.793″
Here’s a video that gives you a visual guide on how to measure a scope height:
What Is the Right Scope Height?
The right scope height is between 1.5 to 1.8″. That said, it can be difficult to say what is the right scope height if we don’t have a specific scope in mind.
But let’s say we have a 30mm scope tube which is the most common size used for bigger rifles. In this case, we need taller scope rings than someone using a 1-inch scope tube.
The lower the scope height, the better because you’ll get a consistent image for your shot. Ensure that your scope doesn’t touch the barrel or other parts of the weapon to have an easier time shooting.
One thing that most people forget when determining the right scope height is a firearm’s power. A powerful rifle produces more recoil, which can damage your scope. As such, we suggest you mount the scope higher.
Does Scope Height Affect Ballistics?
Scope height doesn’t have any effects on your ballistics, but it will definitely affect your scope adjustments. If you’re an average shooter, having a high or mounted scope doesn’t have much advantage. All that matters is that you’re comfortable.
However, when shooting long distances, scope height matters. When you mount your scope high, you are at an advantage in that you can make more adjustments out of your scope.
What Is Height Over Bore or Sight Height?
Height over bore or sight height is the distance between the center of the bore and the center of the scope.
You will need to input this figure into ballistic calculators to get the ‘DOPE’ for your particular rifle. Dope is the ballistic data that helps you when shooting targets at different distances.
If you have this, you’ll definitely find an accuracy improvement, no question.
For more reading check out our guide to the most common scope tube sizes.
Frequently Asked Questions
What is the average sight height?
The average sight height is between 1.5 to 1.8 inches. This will give you a comfortable shooting position for most rifle scope combinations.
How is sight height calculated?
Sight height is calculated by adding the center of the bore, the center of the scope, and the distance between the bottom of the scope and the top of the barrel.
Dakota Potts is a gunsmith, armorer, and gun rights advocate with nearly 10 years of experience. He is well respected in the industry and his work has appeared on various industry leading firearm publications. He enjoys learning about firearm history and technology. You can follow Dakota Potts on Youtube or see his Facebook.