🎯 Sight Pin Gap Calculator

Enter two distances and their sight pin settings (from your sight's scale) to estimate the setting for another target distance by linear interpolation.

Distance 1 (yd)

Pin setting at distance 1

Distance 2 (yd)

Pin setting at distance 2

Target distance to estimate (yd)

Straight-line interpolation between two marks

The page takes two sight settings you have already verified and assumes the scale moves evenly between them:

gap per yard = (setting2 − setting1) ÷ (distance2 − distance1)
estimate     = setting1 + gap per yard × (target − distance1)

With the defaults — 1.00 at 20 yd, 1.60 at 30 yd — the gap per yard is 0.6 ÷ 10 = 0.0600, so 25 yd estimates as 1.00 + 0.06 × 5 = 1.30. The settings are whatever your own sight scale reads; the tool never touches yardage marks printed on a tape.

Where the straight line stops being true

Interpolate, do not extrapolate. Arrow drop grows faster than distance, so the same 0.06 per yard taken out to 40 yd predicts 2.20. If your shot-in 40 yd mark is nearer 2.40, that difference is the curve the straight line ignores.
Same bow, same everything. The two known settings must come from one sight scale with the same peep, anchor, arrow and draw weight. Change arrows and every mark moves.
This is not barebow gap shooting. Despite the name it interpolates a sight scale, not the gap between arrow point and target.

Shoot the estimate into a target face before it counts. Note also that entering the same figure for both distances divides by zero and prints NaN rather than an error.

Frequently asked questions

How do I find a sight setting for a distance I cannot shoot?

Take two marks you have already sighted in either side of it and let the tool split the difference — 20 and 30 yd give you 25 yd. Confirm it on a target at the first opportunity; an interpolated mark is a starting point.

Why is my long-range mark further out than the estimate?

Because arrow drop is not linear: flight time grows with distance and drop with the square of it, so a per-yard gap measured at 20-30 yd under-predicts what 50 or 60 yd needs. Re-measure the gap from marks close to the distance you care about.

What does gap per yard mean?

It is how much your sight scale moves for one yard of distance, shown to four decimals. The default pair works out at 0.0600 per yard, so ten yards is 0.60 of scale movement.