Difference Between T8 and T12 Bulbs (With Table)

T8 and T 12 are both fluorescent bulbs. They have been in the market for a long time. The T in T8 and T12 bulbs stand for “tabular,” and the number that follows T represents the diameter or size of the bulb. T8 bulb was launched back in 1981, which was a few years after the T12 bulb was launched in 1938.

T8 Bulb vs T12 Bulb

The difference between T8 and T12 bulbs is that T8 bulbs have a diameter of 1.5 inches, whereas T12 bulbs have a diameter of 1 inch. T8 bulbs are a better choice than T 12 bulbs. This can be easily proved. T8 bulbs have a better color rendering index as well as high efficacy. However, a T12 bulb is only able to maintain either the color rendering index or the efficacy.

T8 bulbs are florescent bulbs with rare earth phosphors coating. T8 bulbs It is a good choice if one doesn’t need many lumens. A T8 bulb has a lower lumen. It also consumes less wattage than other bulbs present in the market. They do not require a long time to start, even at very low atmospheric temperatures.

T12 bulbs are one of the oldest types of bulbs present in the market. As their name suggests, they are bigger and bulkier than other bulbs available. They are very cheap compared to the T8 ones. They take time to start when powered on. They seem to be dim and inefficient during low temperatures and hence are not a great choice for places with cold weather.

Comparison Table Between T8 and T12 Bulbs

Parameters of ComparisonT8 BulbT12 Bulb
Life spanThey have a longer life than T12 bulbs.They have a shorter life span than T8 bulbs.
Initial StartingThey do not take time to glow.They take a long time to glow than T8 bulbs.
SizeThey are smaller in size compared to T12 bulbs.They are bigger and bulkier than T8 bulbs.
Wattage ConsumptionThey consume less wattage than T12 bulbs.They consume more wattage than T8 bulbs.
CostThey are expensive than T12 bulbs.They are cheaper than T8 bulbs.

What is T8 Bulb?

T8 bulbs were launched back in 1981. They are expensive compared to the rest tabular models. Back in those days, T8 lamps were great as a choice. The T8 bulbs used new phosphor technology, which made them popular in the market. T8 bulbs consumed less wattage and were quite efficient. They work very well in cold temperatures and do not require a long time to start. They also have good and improved color statistics.

They have good color retendering index as well as great output. These lamps are coated with rare earth phosphors instead of traditional halo phosphates coating. But this rare phosphors coating is expensive to the halo phosphates ones and ultimately can make the bulb expensive as well. Hence, the cost of this bulb was reduced by coating the tube with a blend of rare-earth phosphors and traditional halo phosphates.

The retendering color index of a bulb is determined by the coating of the lamp. T8 lamps are available in many color temperatures such as warm, neutral, cool, and very cool. The ballast that we install in the fixture is responsible for starting the bulb initially.

Rapid start ballast must be a great choice for people living in cold places. However, there are several disadvantages of using a T8 bulb. They emit UV and IR light which is neither good for the eyes nor the environment. The mercury content of the T8 bulbs makes them difficult to disposable. A T8 bulb is about 30 percent less efficient than a modern-day LED light.

What is T12 Bulb?

T12 bulbs work on the principle of electromagnetic induction, which is not very efficient. It usually uses magnetic ballast. One can use the same fixture for The T8 and T12 bulbs.

A T12 bulb is about 6 percent less bright than a T8 one. T12 bulbs consume more energy but release less output than LED. A typical T12 bulb consumes a wattage of about 172 watts which is 71 percent more than a modern LED. This huge difference between these two screams for the replacement of T12 bulbs.

T12 bulbs are about 80 years old. In the past, they may have been a great choice, but now they surely need to be replaced by new incoming modern bulbs. T12 bulbs have been stopped from their manufacturing in many countries.

Research has shown that T12 bulbs are very less efficient, have a short life, difficult to dispose of due to their high mercury content. In today’s world, T12 bulbs are a big no just because they have better replacements.

Main Differences Between T8 and T12 Bulbs

  1. T8 bulb has a longer life than that of T12 bulb.
  2. T8 bulb is about 1 inch in diameter, whereas T12 bulbs are about 1.5 inches in diameter.
  3. T8 bulbs work with the help of electronic ballast, whereas T12 bulbs work with the help of magnetic ballast. However, both these bulbs can be used on the same fixture.
  4. T8 bulbs take less time to glow initially. They also work very well even in low temperatures, whereas T12 bulbs take time to glow. They can go dim or even stop working during cold weather.
  5. T8 bulbs are more expensive than T12 bulbs.


Both T8 and T12 bulbs are fluorescent bulbs. They were invented during the late 20th century. They both were great inventions back then. T12 is older than T8. T8 was considered to be a great replacement to T12 back then. However, the incoming of LED has changed the lighting industry to whole another level. LEDs have all advantages over typical fluorescent bulbs and can also save the environment from toxic mercury present in the bulbs.


  1. https://arsvot.org/index.php/anp-jssh/article/view/26
  2. https://ieeexplore.ieee.org/abstract/document/7161181/
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