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The Daily Insight

What is the standard size of a fluorescent light

Author

Isabella Wilson

Published Mar 25, 2026

While there are multiple types of LED and fluorescent tube lights, the three most common are T12, T8 and T5. The terminology comes from “T” for “tubular” and the diameter of the bulb in eighths of an inch, so “T8” represents a tube of 8/8ths of an inch, or 1 inch.

What is standard diameter of tube light?

Typical diameters are T12 or T38 (11⁄2 in or 38 mm) for residential lamps with magnetic ballasts, T8 or T26 (1 in or 25 mm) for commercial energy-saving lamps with electronic ballasts, and T5 or T16 ( 5⁄8 in or 16 mm) for very small lamps, which may even operate from a battery-powered device.

How long is the average fluorescent light?

While, a 48-inch fluorescent lamp will, on average, burn for 20,000 to 34,000 hours, the quality of light output gradually decreases over time. The “economic life” of a fluorescent lamp is only about 60 percent that of its actual burn time.

Are all fluorescent lights the same size?

Fluorescent tubes come in a range of sizes. … Fluorescent tubes are measured in eighths of an inch. A T8 has a one inch (8/8 inch) diameter, a T5 has a 5/8 inch diameter, and a T12 is a 12/8 inch (1.5 inch) in diameter.

What is the diameter of a T8 fluorescent tube?

A T8 lamp (on the right in the figure below) is eight-eighths of an inch, or one inch (2.54 cm), in diameter.

How do I measure a fluorescent tube?

Fluorescent tubes are measured in eighths of an inch, with the measurement being drawn from pin to pin at the end of the tube. The wattage level is dependent on the length of the fluorescent tube. The sizes of fluorescent tubing range from T2 to T17.

Will a T8 fit a T12?

T8 tubes are simply 1 inch in diameter versus the 1.5 inch diameter of T12 tubes. In an effort to make LED tube lights compatible with the internal dimensions of most fixtures, you will find that most LED tube lights feature a T8 or 1 inch diameter. They can indeed be used in T12 fixtures.

What is the difference between T8 and T12 fluorescent bulbs?

The main difference between T8 and T12 tubes is the tube’s diameter. T12 tubes are 1.5″ in diameter while T8s are just one inch. All other things—socket sizes, lengths, distance between pins—are the same. T8 LED tubes won’t fall out if you try to install them in a T12 fixture—they’ll fit just fine.

How do I know if I have T8 or T12?

If no markings are available, the size in diameter of the tube is the easiest way to determine the type you have installed. T8 tubes are 1-inch in diameter and T12 tubes are 1 1/2 -inch.

Can I replace fluorescent tubes with LED?

Yes, you can replace fluorescent tubes with LED tubes or LED-integrated fixtures. If you just want to replace the bulbs, you can use plug-and-play, direct-wire, or hybrid LED tubes.

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What is T5 fluorescent tubes?

A T5 is a type of fluorescent tube. It differs from a T12 and a T8 in its diameter. All T5s are 5/8ths of an inch (T8s are exactly 1inch thick and T12s are 12/8ths or 1.5 inches thick). T5s are 16mm in diameter making them the thinnest fluorescent tube out of the three.

What is the difference between a T5 and a T8 fluorescent bulb?

The major physical difference between T5 and T8 light bulbs is the length and diameter of the tube itself. The T5 tends to be slightly shorter than the T8 tube, and is significantly smaller in diameter. This factor is important to consider when looking at your fixture, because the two tubes are not interchangeable.

Which is brighter T12 or T8?

The Standard T12 lamp produces 2,650 initial lumens per lamp. The standard T8 produces 2,800 initial lumens per lamp, 6% brighter. But the standard T12 lamp produces 2,300 design lumens and the T8 produces 2,660 design lumens. … Design Lumens are the average lumen output of the lamp after 40% of its rated life.

Are fluorescent tubes being phased out?

The sale of halogen lightbulbs will be banned in the UK from September as part of ministerial efforts to cut carbon emissions. A ban on fluorescent lighting, which is mostly used in offices, will follow in September 2023.

Can I replace a T12 with a T8 tube?

The easiest and lowest price option to replace a T12 is a T8 linear fluorescent. They have become the go-to option for pre-existing T12s. If you still have magnetic ballasts, switching to a T8 will require a ballast swap.

Can I replace T8 with LED?

Type A – LED tube has an Integrated Driver for use on Existing Fluorescent Ballast. Type A LED tubes need an existing T8 electronic ballast to operate. … All you need to do is remove the existing T8 fluorescent lamp and install a new T8 LED Type A lamp.

What is the difference between T5 T8 and T12?

So a T5 is 5/8ths of an inch, a T8 is exactly one inch thick (i.e. 8/8ths) and a T12 is 12/8ths or one and a half inches thick.

How do I choose a fluorescent light bulb?

First, you will need the diameter or how wide it is around. This is expressed as a number such as T8 or T12. The “T” stands for tubular, and the number is a measurement of the diameter in 1/8″ increments. So a bulb with a 1″ diameter would be a T8—eight 1/8″ increments.

How do I identify a T8 bulb?

If the label is missing or illegible, you can measure the diameter to determine the size. The letter “T” will stand for tubular shape and the number will tell you the bulb diameter in eighths of an inch. T8 will have one-inch diameter, the T5 will have a 5/8 diameter, and a T12 will have 12/8 inch or 1.5 inch diameter.

What's better T5 or T8?

T5 lamps are smaller and more efficient than T8 bulbs. T5 lights are the winner between the two, they do cost about 2x more than T8 options. While T8s are cheaper upfront, T5s are a more affordable option long-term and are great for most growing needs.

Is an F40 a T12?

A T12 is 12/8ths of an inch, or 1.5″ in diameter. A T5 is 5/8″ in diameter. All F32 and F40 lamps are essentially 4 foot long lamps (47″ if you don’t count the pins). The FR71T12 is actually a 71″ long x 1.5″ diameter lamp that can handle from 80-120w and is typically run at 100w.

Are T12 bulbs being discontinued?

In effect since July 2012, the legislation eliminates nearly all 4-foot T12 lamps, some 4-foot T8 lamps, most 8-foot T12 lamps, and almost all standard halogen PAR38, PAR30 and PAR20 lamps from the market. T12 technology is over 80 years old. Since that time, lamps and bulbs have been developed that just work better.

What wattage are fluorescent tubes?

TechnologyBallast FactorOperational Wattage34 Watt T12 Fluorescent Tubes0.8843 Watts16 Watt T8 Equivalent LED Tube116 Watts

How many lumens is a fluorescent tube?

Well, fluorescent tubes can only produce about 50-100 lumens per watt (lm/w).

Do LED fluorescent bulbs need a ballast?

No LED bulbs require a ballast, although some are engineered to work with an existing ballast. You will find ballast-compatible or “plug-and-play” LEDs that are designed to replace linear fluorescents, compact fluorescents, or HIDs.

Can LED bulbs go in any fixture?

As long as the mounting base (socket) is the same size and type, you can use an LED bulb in an existing fixture. … LED bulbs have much lower wattage than incandescent bulbs, so it’s important to know the light output (in lumens) for the bulb you’re replacing.

Which is better LED or T5?

LEDs also offer increased light efficiency when dimmed as opposed to T5 fixtures and usually produce more lumens per watt in general, which decreases energy usage and thus, energy costs. A lower wattage of LED luminaire will usually be just as efficient, sometimes more, as a higher wattage T5 lamp.

Can you replace T5 with T8?

T5 lamps cannot replace T12 or T8 lamps because of differences in physical and electrical characteristics. T5 lamps come in different lengths than T8 and T12 lamps. A nominal 4-foot T5 lamp is actually shorter than an equivalent T8 lamp [1149 millimeters (45.23 inches) in total].

What is the difference between a T5 and T10 bulb?

“Five-sided lighting” , Bulbs uses five-sided lighting in order to increase brightness and wider angle of brightness area. In fact, the history of T5 is same as late evolution of T10. We got to solve the problem that the illuminate breadth is not enough, resulting in multi-faceted illumination.

How do I know if my bulb is a T5?

The “T” in T5 indicates the bulb is tubular shaped, while the “5” denotes that it is five eighths of an inch in diameter. The other common lamps are the larger T8 (eight eighths inch = 1″) and T12 (twelve eights inch = 1½” tubes).

What's the brightest fluorescent light?

Fluorescent T5s T5s are fluorescent tubes that are 5/8 of an inch in diameter. These are the newest development in the fluorescent family. Although they are the smallest, they are the most energy efficient and brightest.