International Distance Triathlon - Distance may vary from ½ mile to 1.5k

Olympic Distance Triathlon - 1.5k or 1700 yards

Half Iron Distance Triathlon - 1.2 miles or 2000 yards

Iron Distance Triathlon - 2.4 miles or 4000 yards

25 YARD POOL
1 length = 25 yards (from wall to wall)
2 lengths = 50 yards
4 lengths = 100 yds
¼ mile = 500 yards = 20 lengths
½ mile = 800 yards = 32 lengths
1 mile = 1700 yards = 68 lengths
1.2 miles = 2000 yards = 80 lengths
2.4 miles = 4000 yards = 160 lengths

50 METER POOL
1 length = 50 meters
2 lengths = 100 meters
¼ mile = 400 meters = 8 lengths
½ mile = 800 meters = 16 lengths
1 mile = 1500 meters = 30 lenghts
1.2 miles = 2000 meters = 40 lengths
2.4 miles = 4000 meters = 80 length