Estimate FPS from your bow setup
IBO speed is measured at 70 lbs draw weight, 30" draw length, and 350 grain arrow with no accessories. Deductions: ~10 fps per inch under 30" draw length, ~15-20 fps per 10 lbs under 70 lbs, ~1 fps per 3 grains over 350, ~3 fps for peep sight, and ~1 fps per 5 grains of string accessories. Real-world speed is typically 15-25 fps below IBO.