Where does this come from, and can I check it?

The T8 label means a tube one inch wide, which is about 25 millimetres. The figure is taken from National Institute of Standards and Technology, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a everyday life fact?

Yes. It sits on the Everyday Life shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

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The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

Fluorescent tube numbers measure eighths of an inch

The T8 label means a tube one inch wide, which is about 25 millimetres In a tube code the T stands for tubular and the number is the diameter in eighths of an inch. T8 is therefore one inch, about 25 millimetres, and the older T12 is one and a half inches. A fluorescent tube is a low-pressure mercury discharge, so its diameter affects how efficiently it turns current into light. It sits in Mondo's everyday life collection, one of 200 facts that each trace back to the reference below.

Where this comes from

National Institute of Standards and Technology

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

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Tags: lighting, standards, measurement

Fluorescent tube numbers measure eighths of an inch: the short answers

Where does this come from, and can I check it?: The T8 label means a tube one inch wide, which is about 25 millimetres. The figure is taken from National Institute of Standards and Technology, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a everyday life fact?: Yes. It sits on the Everyday Life shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.