take your 1/8 mile ET and divide it by .65....it'll give you a very close approximation to your 1/4 mile ET; ie. your 1/8 mile was 8.0179/.65 = 12.33 1/4. It usually is within a .1 of a second unless you hit a deer at the 1,000 ft mark (that takes off about 3. of a second). Keep up the good work and have fun doing it, Mark