Arrow Cut Length Calculator by Rest Type

Cutting arrows is the one step in a build you cannot undo, and the offsets that make it safe come from a piece of geometry most guides skip: at full draw, your nock sits draw length minus 1.75 inches from the rest. This calculator applies that, adds the right allowance for your rest type, and warns you if the result leaves too little shaft forward of the rest.

The geometry nobody explains

Every compound is specified in AMO draw length, which is the distance from the nock groove at full draw to the pivot point of the grip, plus 1.75 inches. The pivot point is the deepest part of the grip throat, and on essentially every riser the berger hole where your rest mounts sits directly above it.

So the actual physical distance from your nock to your rest at full draw is draw length minus 1.75 inches. For a 28 inch draw archer that is 26.25 inches. An arrow cut to 27.5 inches therefore has 1.25 inches of bare shaft sitting forward of the rest before the insert and point are counted at all, and adding a field point puts the tip more than two inches clear.

That single fact explains why arrows can legitimately be cut shorter than draw length, why the common advice to "cut to your draw length" is safe but conservative, and why the same draw length produces different correct answers for different rests.

Cut length by rest type

Two of these deserve a note. Full containment rests go longer rather than shorter because the failure mode is different: if the point drifts back into the bristles at full draw, the shot is unpredictable and the rest can be damaged. Traditional setups go longest of all because a finger release allows creep at full draw, and an arrow that slips back off a shelf is genuinely dangerous. Trad archers also want the extra length for spine reasons, so the two motives point the same way.

The safety line

Never cut an arrow short enough that the point can come back behind the rest at full draw. If it does, the arrow can derail on release and drive back toward your bow hand. This is the one arrow building mistake that causes injuries rather than bad groups. Have a partner watch from the side at full draw before you cut a full dozen, and if there is any doubt, leave it longer.

The calculator flags this automatically. It requires at least half an inch of bare shaft forward of the rest at full draw, before the point is counted, which leaves a real margin for creep, draw length drift as the string stretches, and the fact that you will not always come to exactly the same anchor.

Cut long, shoot, then trim

The professional sequence is to build one arrow, not twelve. Cut a single shaft half an inch to an inch longer than the calculator suggests, fletch it, and shoot it alongside a bare shaft. If the bare shaft indicates the arrow is weak, cut a quarter inch and repeat. Each quarter inch you take off stiffens the arrow by roughly the equivalent of a pound and a quarter of bow weight, so the adjustment is fine grained enough to dial in.

Only once that single arrow tunes do you cut the rest of the dozen to match. This is slower and it is unambiguously cheaper: a dozen good shafts costs more than an arrow saw, and there is no recovering from a dozen cut half an inch too short. Confirm the spine you are aiming at with the arrow spine calculator before you start, since length and spine are the same conversation.

Cutting long and trimming down only works if you can actually shoot each iteration, ideally with both a bare shaft and the broadhead you intend to use. A target that stops bare shafts without burying them and is rated for broadheads lets you run the whole sequence in the backyard rather than booking range time for every quarter inch.

What changes when you cut

Length is the most powerful single variable in arrow building, and trimming an inch moves three numbers at once:

• Spine stiffens by roughly the equivalent of five pounds of bow weight per inch removed. This is the standard correction for an arrow that bare shafts weak.
• Total weight drops by one GPI per inch. On a 9 GPI hunting shaft that is nine grains, which matters if you are near the 5 grains per pound safety floor. Recheck with the total arrow weight calculator.
• Front of centre rises, because you removed mass from the rear and shortened the lever arm at the same time. Cutting is the only FOC adjustment that does not cost you arrow speed, which makes it the cheapest one available. Confirm the new figure with the FOC calculator.

Cutting technique

Carbon shafts must be cut with a high speed abrasive wheel arrow saw. A hacksaw, tubing cutter or rotary tool crushes the fibres and leaves a shaft that can splinter under load. Spin the shaft against the wheel rather than pushing it straight through, square the end afterwards so the insert seats flat, and clean the inside before gluing. Wear eye protection and keep carbon dust away from your face and hands.

Aluminium shafts cut more forgivingly but still need to be squared, and the burr on the inside edge must be removed or the insert will sit crooked. Either way, measure twice from the nock throat with the nock actually installed, because nock depth varies between brands by enough to matter.

Related tools

• Draw length calculator: the input this entire page depends on
• Arrow spine calculator: length and spine are the same decision
• Total arrow weight calculator: recheck the 5 gr/lb floor after cutting
• Best archery rangefinders: once the arrow is right, distance is the last variable