Understanding the Inputs

Here's a plain-English explanation of every field in the generator.

Arrow Speed (fps)

The speed of your arrow in feet per second, measured at the muzzle (just past the arrow rest). This is the most important input. Even a 5 fps error here can push your 60-yard mark off by several inches. Always use a chronograph if you can.

Sight Radius (inches)

The distance from the centre of your peep hole to the centre of your front pin housing. This tells us how much your pin physically moves per yard of range change. A longer sight radius means finer adjustments are possible.

Draw Length (inches)

Your actual measured draw length, typically from the nock groove to the pivot point of the grip, plus 1¾ inches. Used to adjust the IBO speed estimate to real-world fps if you don't have a chronograph.

Arrow Weight (grains)

The total mass of your finished arrow (shaft + tip + insert + nock + vanes). IBO speed is measured at 350 grains. If your arrow is heavier, your real-world fps will be lower — roughly 3 fps per 10 grains over 350 gr.

Max Range (yards)

The furthest distance you want marks on your tape. The generator creates tick marks from 20 yards up to this value. Most bowhunters choose 60 or 80 yards. Ranges above 80 yards require a one-time unlock.

Elevation (feet) — Altitude Correction

Your shooting altitude above sea level. Thinner air at higher elevations reduces aerodynamic drag, making your arrow shoot slightly flatter than at sea level. This matters most at distances over 50 yards and at elevations above ~5,000 ft. Enter 0 to disable the correction.