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Hun: Unit of measure for metal rebar

image DSC02044.JPGA coolthaihouse reader was interested in the determining the specifics regarding the unit of measure commonly used with rebar – the hun (หุน). I’ve asked the question regarding this unit of measure before and was assured that each hun was equivalent to 3 millimeters in diameter. So a 3 hun piece of rebar should be 9 millimeters in diameter, correct?

Not so quick, it also depends on the grade of the rebar. Light designation (bow เบา) rebar is less expensive and can be formed (bent) on an anvil using hand tools. The diameter will also be less than the associated hun designation, so a 3 hun light rebar might only measure slightly over 6 millimeters in diameter. On the other hand ‘full’ designation (dem เต็ม) should always be 3 millimeters in diameter for each hun designation. Our foreman here says the differential between bow and dem is 3 mm at each hun designation. So, for example, 4 hun dem rebar would have a diameter of 12 mm where as 4 hun bow would have a diameter of 9 mm.

One definition in a Thai – Thai dictionary which refers to measure is this: standard Chinese unit of measure with one hun = 1.5 / 16 inches. This works out to be different again from 3 mm, falling somewhere in between 2 to 3 mm. As a practical matter, 3 mm is the standard used when applied to rebar diameters.

Thanks to reader Doug for looking into this……

Update 28-May. Just bought some 6 hun PVC water line sections. The receipt prints the size as 20 mm. or 3/4 “. Just measured it and this is correct for the inside dimensions. When asked about the descrepancy (why is it not 18 mm which would by 6 times 3 mm?) my foreman says the hun measure isn’t the same when applied to PVC piping.

1 Comment

  1. I always measure the rebar before buying. In small villages sometimes the rebar is smaller than it should be. It is better to measure before buying than to return it after buying….you will loose face if you return stuff because YOU bought the wrong stuff.

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