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Buying Fluorescent Tube Lights: T5s, T8s & T12s

Posted by Nick Majors on

Fluorescent tubes are used in a wide variety of different applications, from offices to washrooms to kitchens to everything in between. However, when it comes to linear fluorescent tubes, getting the right bulb can seem a little confusing. There are a lot of different options and it's easy to get lost in all of the different numbers and terminology that you may hear and read. 

The good news is that, despite sounding complex, it's actually quite easy. This buying guide is here to help.

Linear Fluorescent Tubes Buying Guide


The three main types of fluorescent tubes that you will likely encounter are T5s, T8s and T12s. The "T" designation is used to identify the diameter of the tube in eighths of an inch. For example, a T5 is 5/8" (or 15.9mm). A T8 is 8/8" in diameter (or 1 inch - 25.4mm) and a T12 is 12/8" (or 1 1/2" - 38.1mm).

Perhaps the easiest way to distinguish between these different bulb types is to compare them to a Canadian dollar coin. A Loonie is 26.5mm - or just over 1 inch in diameter. Knowing this, you can use this coin to differentiate between different linear fluorescent tubes.

T5, T8 & T12 sizing

As you can see, a T12 is wider than a Loonie, a T8 is about the same size as a Loonie and a T5 is much smaller than a Loonie.

Colour Temperatures

Another number that you may encounter on your tube is the colour temperature. This is usually listed as a three-digit number starting with an "8". The other two numbers indicate the colour temperature in kelvin. Therefore, a bulb that is marked as "827" will be 2700 kelvin or "Warm White" and a bulb marked "841" will be 4100 K.

The chart below lists information for various colour temperatures as well as an approximation of the colour.

Temperature Name
2,700 K Warm White
3,500 K Neutral
4,100 K Cool White
5,000 K Natural Light
6,500 K Daylight
These temperatures and their colours are for representative purposes and the actual light colour may differ. Source: Wikipedia

Linear Fluorescent Tube Lengths

The third number that you need to pay attention to is the length of the tube. When measuring the tube, include the pins on both ends.

This is a straight measurement in inches. For example, a T12 tube may be 24 inches or a T5 could be 12 inches.  

Energy Efficiency & LED Options

When it comes to energy efficiency, despite being older technology, linear fluorescent tubes are relatively energy efficient. They also give off less heat than incandescent or halogen bulbs. LED alternatives are a more recent technology. The main advantage that these bulbs have over fluorescent tubes is lifespan, rather than energy savings.

If you're looking to buy linear fluorescent tubes, we can help. Check out our linear fluorescent tubes page or contact us with any questions that you may have. 

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