Fluorescent lighting is economical to run and uses long-lasting tubes to provide bright and effective general lighting. T4 fluorescent tubes are ideal for home and commercial use for kitchen worktops, in cabinets, under stairs, as a pelmet lamp, or to create a well-lit workstation for DIY, craft, or commercial use. T5 bulbs are great for large space such as schools, supermarkets, offices, and underground railways. T8 bulbs can be used in schools, garages, offices, conference rooms, retail stores, and most other environments.
There can be a lot of variance in fluorescent bulb sizes, particularly with T4's, so be sure to check the length of the bulb you are replacing, don't just go by the information that is on the tube.
Follow the guide below to find the perfect replacement.
How To Measure A Bulb
What you need to know:
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Bulb Diameter
The "T" in lamp terminology represents the shape of the lamp tubular. The number following the "T" usually represents the diameter of the lamp in eighths of an inch (1 inch equals 2.5 centimetres).
Tube Type | T4 | T5 | T8 |
Diameter (mm) | 12 | 15 | 25 |
Diameter (inches) | 1/2 | 5/8 | 1 |
Bulb Lengths
Use the tables below to find the correct bulb. When you select the correct size you will be able to choose various colour temperatures if available.
Length Including Pins
6W | 220mm | 222mm | 230mm | 232mm |
---|---|---|---|---|
8W | 347mm | |||
10W | 353mm | 370mm | ||
16W | 457mm | 468mm | 480mm | |
20W | 567mm | 568mm | 580mm | |
25W | 655mm | |||
30W | 766mm | 767mm |
Length Excluding Pins
6W | 208mm | 205mm | 220mm | 219mm |
---|---|---|---|---|
8W | 330mm | |||
10W | 341mm | 356mm | ||
16W | 440mm | 454mm | 468mm | |
20W | 550mm | 554mm | 567mm | |
25W | 639mm | |||
30W | 752mm | 750mm |
Length Including Pins
4W | 150mm | ||
---|---|---|---|
6W | 225mm | ||
8W | 300mm | 302mm | |
13W | 530mm | ||
14W | 561mm | 563mm | |
18W | 591mm | ||
21W | 855mm | 861mm | 862mm |
28W | 1161mm | 1163mm | |
32W | 1201mm | ||
35W | 1461mm | 1463mm |
Length Excluding Pins
4W | 134mm | ||
---|---|---|---|
6W | 212mm | ||
8W | 288mm | 282mm | |
13W | 517mm | ||
14W | 549mm | 549mm | |
18W | 585mm | ||
21W | 849mm | 849mm | 848mm |
28W | 1149mm | 1147mm | |
32W | 1195mm | ||
35W | 1449mm | 1449mm |
Length Including Pins
15W | 451mm | |
---|---|---|
18W | 600mm | |
30W | 905mm | |
36W | 1213mm | |
58W | 1500mm | 1510mm |
70W | 1775mm |
Length Excluding Pins
15W | 438mm | |
---|---|---|
18W | 580mm | |
30W | 859mm | |
36W | 1200mm | |
58W | 1449mm | 1500mm |
70W | 1763mm |
More Information
We hope you have been able to find the bulb you require using the above information but if you need any more information a lot of customers have found the following guides useful: