How to Measure Arrow Length and Draw Length for Custom Arrows

Draw length is how far you pull the string at anchor. It is not the same as arrow length. TitleX cut length is the finished shaft; that cut starts from a true AMO draw length, then adds rest and broadhead clearance. A wrong draw length puts you on the wrong spine row and the wrong cut in the 3D custom arrow builder.

What AMO draw length actually is

AMO (now ATA) draw length is the distance from the nock throat to a vertical line through the grip’s pivot point, plus 1.75 inches, at full draw. On most compounds the Berger hole sits on that pivot line, which is why shops mark the arrow there and add 1.75 inches.

The number on the cam is the bow’s setting. It should match you. If you outgrew a 28-inch module and still order 28-inch arrows, the shaft is short for the new draw and the spine chart is lying to you.

What you need

• Your hunting compound, or a similar bow you can draw to a real anchor
• A draw-check arrow or a long extra shaft — not a short hunting arrow that can come off the rest
• A tape measure and a helper

Measure it on the bow

1. Draw to the anchor you hunt with. Peep, kisser, and release the way you shoot in the woods. A stretched-out shop pose adds length you will not hold on an animal.
2. Mark the shaft at the Berger hole. Helper marks even with the rest / plunger hole at full draw. Let down. Do not guess from a photo.
3. Measure nock throat to the mark, then add 1.75 inches. Nock throat is the bottom of the groove, not the nock ears. That sum is AMO draw length.
4. Read the cam and compare. If the bow says 27.5 and you measured 29, the module is short or the anchor was sloppy. Fix the bow fit before you cut carbon.

Wingspan is only a check

Fingertip-to-fingertip wingspan in inches, divided by 2.5, is a starting guess. It is often within about a half inch. It is not a substitute for a full-draw mark on your hunting bow. Long arms, a high peep, or a short-draw hunting form will disagree with the formula. Use wingspan to see if a used bow is in the neighborhood, then measure on the string.

How to measure arrow length (cut length)

1. Install the nock you hunt with.
2. Measure from the nock throat to the end of the carbon. Do not include the insert collar past the shaft or the point.
3. Start at AMO draw length plus the extra you need so the broadhead clears the rest at full draw. Many compound hunters land about an inch past AMO. Drop-aways, overdraws, and mechanicals change that.
4. Set that cut in the builder so FOC updates, then pick spine on the TitleX spine chart.

Extra length adds mass and weakens dynamic spine. Cutting shorter stiffens the reaction. Draw weight on a compound is rated at a listed draw length. If you shoot shorter than the spec, you are not holding the limb-stamp pounds.

If the numbers fight each other

• Cam says 28, wingspan says 29, full-draw mark says 28.25 — trust the mark on your bow at anchor
• String slap on the arm or peep that will not settle — draw is often long
• Cramped bow arm and a floating anchor — draw is often short

Recurve, longbow, and traditional anchors do not use a cam module. Measure those on the traditional draw-length page.

Related resources: draw length calculator, measure traditional draw length, arrow spine chart, 3D custom arrow builder, arrow wrap installation.