T5 and T8 Fluorescent Tube Wattages and lengths

Fluorescent tubes for aquarium use come in two commonly used sizes, T5 and T8, which refers to the diameter of the tube. The number refers to how many eighths of an inch in the tubes diameter, so a T5 is 5/8ths of an inch and a T8 is 8/8ths of an inch - or just 1 inch!

A Tubes wattage depends on its length and diameter. The table below shows the wattage for different types and lengths.

Length (cm/inches) T5

54.9 / 22"       24 watt

84.9 / 34"       39 watt

114.9 / 46"     54 watt

144.9 / 60"     80 watt

Length (inches)      T8

15"  15 watt

18"  15 watt

24"  20 watt

30"  25 watt

36"  30 watt

42"  40 watt

48"  40 watt

60"  58 watt

To find the correct tube you only need to match the correct length or wattage, i.e. every 15" T8 lamp is interchangable regardless of wattage.

Note: There can be some variation in T8 wattages i.e. plus or minus 3 depending on the manufacturer.