Try This, some one else posted it I just copied.


This chart works out pretty darn close. The only thing is you have to beable to shoot pretty good groups. The tighter your groups the better you can measure. Plus, you have to be dead nuts on sighted in to begin with. Anyway,,.... it does work. Use the bottom chart(the red one)where I've realigned them for easier reading. Shoot at a target from 20 yards away with your 20 yard pin. Have your spot near the top of the target because you have to allow room for the next group to fall low. Make sure you're on. Back up to 30 yards and shoot the same spot with your 20 yard pin AGAINMeasure the distance between the center of the two groups. Read from the chart to see your speed. For example: If you get a drop of 13 inches your speed is 258. The 60/30 foot chart(20 years/10 yards) chart is for really slow bows, like trad stuff.

DISTANCE= 90ft and 60ft (30yrds and 20yrds)

INCHES= 8 9 10 11 12 13 14 15 16 17 18 19
FPS=322 310 294 280 268 258 248 240 232 225 219 213

DISTANCE=60ft and 30ft (20yrds and10yrds)

INCHES= 5 6 7 8 9 10 11 12 13 14 15 16
FPS= 322 294 272 255 240 228 217 208 200 192 186 180


Drop in trajectory between 60 and 90 feet (20-30 yards)

Speed Drop


322 8
310 9
294 10
280 11
268 12
258 13
248 14
240 15
232 16
225 17