Old Irish Units of Measurement Were Pretty Weird and Cool


I’ll have an ordlach of honey, honey. And a dorn of tea. And make it snappy.

So you think you are having trouble coping with the metric system? Hopefully all 6 billion of us on the planet will eventually all be using the same system and be able to communicate better. But back in olden-day Ireland, we used some crazy measurements. And they are awesome. Here at the Almanac, we wish we could go back to buying a méisrin of ale.

Here’s some measurements used in old Irish law.


A troighid (foot) was the length of a man’s foot, divided into twelve ordlach (thumb-lengths). These figures assume a man’s foot measured 25 cm (10 inches). Mostly, the Irish liked to measure things using body parts. Because pretty much hopefully everyone had all of them.


If you were lucky enough to own land that was 12 forrachs in length by 6 forrachs in width, you had one tir-cumaile (i e. ‘cumal-land’).


The tir-cumaile, “land of three cows” was an area of land that was at some point worth three cows. It is sometimes wrongly interpreted as the area needed to graze three cows. In modern Ireland, a cow grazes on about 0.4 ha, so twenty or more could graze a tir-cumaile. So, a tir-cumaile is the equivalent of 9.3 hectares or 23 acres. It equalled 72 square forraigh.Put it this way, Ireland is 870,000 tir-cumaile.

Other area measurements:

  • An achar was an acre, adopted after the Noman invasions.   
  • A seisrech was the measurement used for ploughable land.   
  • Baile means town, the term “townland” is still used to designate very small named areas in the countryside.
  • Tuath was originally a term for a petty kingdom. 
  • A magh-space was a unit set at the distance from which a cock-crow or bell could be heard.

A hen’s eggshell was used as a standard unit, roughly 55 ml. A méisrin was 12 eggshells or about 1 pint.

Eggshells: a perfectly sensible unit of measurement


The smallest weight used was a grain of wheat. The grain (0.05 grams) had to be taken from very best wheat, whatever that means. So I guess you couldn’t use the mouldy leftovers from last year.

Unga or ounce (576 grains of wheat or 28 grams) was the standard used in weighing metals. The word seems to have been borrowed from the Latin uncia. But there was an older native Irish word, mann, for the ounce.

A pinginn was a penny, about 0.4 grams. A screpall was a scruple (1.2 grams).  

So how are you feeling about the metric system now? Sounds easy, considering. We don’t want to be using egg shells to measure out honey… Or counting grains of the very finest wheat to weigh something we probably shouldn’t be buying anyway. Nope, we’ll stick with grams and litres, thanks – or ounces, pints and miles at the very least.

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