What’s a bow square, aka, T-square?

Every archer needs a bow square. It’s just one of those tools that archers should have on hand to help out with a number of tasks.

Also called a T-square because of its shape, a bow square is a measuring device that can be clipped to the bow string. There will be measurement lines on both the vertical and horizontal bars of the square. On some squares the long ruler is rounded, on others it’s flat. Compound archers tend to prefer the rounded squares, while recurve archers opt for the flat ones.


Setting the nocking point.

Recurve archers are going to use a square in multiple ways. They will use it to set their nocking points. They will clamp the square to the string, set the ruler on the bow’s arrow rest or shelf and then refer to the vertical ruler that’s against the string to set their nocking points. There will be a mark letting the archer know where dead center or “zero” is located, and then lines measured in sixteenth inches above and below that zero.

Recurve archers shooting ILF or Formula bows also will use a square to check tiller measurements for their top and bottom limbs. The tiller measurement is taken from the belly of the limb, just above or below the riser – depending on whether you’re measuring top or bottom limb – to the string on a level plane.


Measuring tiller of the top limb on a recurve bow.

The tiller measurement affects how the bow sits in your hand. If the tiller is not set correctly – to your shooting style and preferences – then the bow might lean forward or backwards. Tiller also makes sure both limbs work in unison. Some archers will want the tiller measurements to be the same between the limbs and the string, while others might like one to be longer than the other. Tiller adjustments are made by turning limb bolts in or out.

Arguably the most frequent use of a bow square for a recurve archer will be to measure brace height. Brace height is the distance from the deepest part – throat – of the grip and the bow string. For consistent shooting, that distance must always be the same, yet it has the potential to change almost every day.


Measuring brace height on a recurve bow.

Every time you string and unstring your bow, you should measure the brace height. As you shoot a bow repeatedly, you also should periodically measure brace height.

If you measure it and it’s a bit longer than normal, unstring the bow and take a few twists out of the string. If it’s below normal, add some twists to the string.

Compound archers will want a bow square primarily during initial setup to help position their nocking point. As mentioned, compound archers often prefer the rounded square because the cylindrical, long ruler imitates an arrow shaft. The “shaft” sits on the arrow rest, and the other end is clipped to the string. There are lines on the vertical ruler indicating where nocking points – usually D-loop material on compound bows– should be placed to surround the arrow.


Setting the D-loop position on a compound bow.

Some archers like to nock their arrows a bit above dead center, and so they can use a bow square to set their nocking points at a specific measurement above the center.

What is brace height?

Brace height. It’s something every archer should know about, regardless of the bow they shoot, because it affects us all.

But what is brace height? And why should we care about it?

Brace height is the distance between the string and the deepest part of the bow grip.

measure brace height

For modern compound bows, the brace height is going to be set by the manufacturer, and you’ll want to stick to those settings to get peak performance out of your bow.

Manufacturers of recurves and longbows will recommend ideal brace heights for individual models, and it’s then up to the archer to twist or untwist the bowstring to achieve the ideal brace height. You add twists to the string to increase the brace height, and untwist the string to shorten it.

If you aren’t able to find the recommended brace height for your recurve, below is a chart of brace height measurements generally accepted within the industry for bows of the specified lengths.


Brace height is critical in two areas – arrow speed and bow forgiveness.

Generally speaking, a shorter brace height helps a bow generate more arrow speed. Let’s say you took two bows set at 70 pounds, with a 29-inch draw length, and one has a 6-inch brace height and the other 7 inches. If you shot the same arrow from both bows, the bow with the 6-inch brace height should shoot the arrow faster than the other.

brace height bows

Notice the left bow’s short brace height as compared to the one on the right.

The bow with the shorter brace height pushes the arrow longer than the other.

A bow’s forgiveness relates to accuracy. A forgiving bow minimizes an archer’s mistakes, while an unforgiving bow magnifies them.

Bows with shorter brace heights tend to be less forgiving than those with longer brace heights, because the string is in contact with the arrow for a longer period. An archer therefore has to maintain perfect form for a longer stretch, until the arrow is in the air.

Compound target bows intended primarily for precision, bull’s-eye target shooting, for example, rarely have brace heights under 7 inches. Eight-inch and 9-inch brace heights are not uncommon.

brace height long

Conversely, compound bows made for hunting and 3-D target shooting, where arrow speed is more important, typically have brace heights of 5-7 inches.

brace height short

Target bows are slower, but more forgiving, while hunting and 3-D bows are faster, but less forgiving.

And it’s all because of brace height.