If you are new to owning a weapon, then you probably get confused when you hear the term co-witness in relation to a red dot sight or holographic sight. There are really only two different types of co-witnessing you can choose from: absolute co-witness or 1/3 co-witness. There are pros & cons to each sight setup. In this post, we’ll help make your decision between absolute vs 1/3 cowitness easy! Read on to see which is right for you.

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Absolute vs 1/3 Cowitness Red Dot Sights

There are many benefits to using a red dot sight or holographic sight. However, you have to set up your co-witness settings correctly to get the most out of your optic. Co-witness refers to the relationship between the optic and iron sights. Some people don’t even know that you can use your red dot and iron sights together! The height of your optic is critical to get right. Here are the two main co-witness strategies.

Absolute Co-Witness – When the iron sights align directly in the center of an optic. The iron sight aiming point aligns with the red dot.
Lower 1/3 Co-Witness – When the iron sight lines up with the bottom 1/3 part of the optic. The iron sight aiming point is below the red dot.

So which co-witness sights are best? It really depends on personal preference. In the sections to come, we’ll break down the pros and cons to each co-witness setup.

What Is Absolute Co-Witness?

Absolute co-witness is when your iron sights align perfectly with the center of your optic. In other words, the red dot has a shorter optical sight mount.

Because the iron sights and red dot line up perfectly, it makes it very easy to zero your optic. The smaller sight height is better for a low cheek weld or specific weapons like an AK-47 or shotgun.

However, many shooters believe it is redundant to have the iron sights and red dot align perfectly. They do not want to shoot with both iron sights and red dot sights! Also, some shooters avoid absolute co-witness sight because the iron sights obstruct the sight picture.

What Is 1/3 Co-Witness?

Co-witness sights are typically used in the lower 1/3 of the optic, which means that the iron sights align with the bottom 1/3 of the sight picture. This can be helpful for getting on target quickly and accurately, but it can also have its drawbacks.

For one thing, it can cause confusion with some shooters when trying to make a quick decision and fire. It takes the brain a second to pick between the iron sights or red dot sight. And if your optic is turned off or goes dead, you may not be able to use the iron sights as well.

Most shooters prefer lower 1/3 co-witness sights. There are a few main reasons for this.

More comfortable & allows for natural body positioning
Room for large headgear
Minimizes any rail attachment obstruction

Absolute vs Lower 1/3 Cowitness Sight Tips

How do you know if you should use lower 1/3 co-witness or absolute co-witness sights? Well, it depends on your iron sight setup.

Flip-up iron sights – Most people who have flip-up iron sights on their weapons should be using the absolute co-witness most of the time. The iron sights are usually flipped down most of the time anyway,
Fixed sights – If you’re running fixed iron sights, then you should be using the lower 1/3 co-witness. That way, you’ll have a better view of your red dot, and you won’t have to worry about aligning your sights perfectly.
No iron sights – If you don’t have iron sights at all, then there is no co-witness. Although it is still probably best to go with the absolute co-witness sights setup.

Night Vision Optics

Night vision optics do not co-witness with iron sights. Regular iron sights do not project any light and are not highly visible under night vision. Night vision sight mount height is only made so that it alights better with NV goggles of the shooter.

Where To Buy

If you’re sold on either absolute or lower 1 3 co witness, then its time to get your own sight. Check out our comparison of the EOTech EXPS vs XPS, Aimpoint Comp M5 or T2, or Holosun 407k vs 507k! EOTech, Aimpoint, and Holosun are 3 of the top optic manufacturers in the business. Take a look and see which sight fits your needs best!

FAQs: Co-witness

What is absolute Cowitness height?

With absolute co-witness setup, the optic is aligned directly with the iron sights. The optic is usually mounted about 2.6″ above the weapon bore.

What is the height of a lower 1/3 Mount?

The height of a lower 1/3 mount depends on the specific red dot sight you use. For most sights, a 39mm mount is the correct height.

What does it mean for a red dot to co-witness?

When the red dot co-witnesses with the iron sight, it means that they are lined up perfectly. This setup is usually used by people with flip up iron sights.

What height mount for red dot?

There are three standard mount heights for red dot sights – .75 inch, .83 inch, and 1 inch. Normally, you can make slight adjustments to the optical sight mount to get your desired sight picture.

What height are AR15 sights?

AR15 sights are typically 2-1/2 inches high. This measurement is important to know because it determines how high or low the rifle will be when aimed at a target.

The Bottom Line

Now you know the difference between lower 1/3 co-witness and absolute co-witness sights. There is no best setup, it is just a matter of choosing your desired sight picture. Both have their own unique set of pros and cons. If you get to chance, shoot a few rounds downrange and see which is your preferred sight picture.