Both names are used today, but I think scale has become more popular.
I tend to use scales, but I've hear younger people saying scale.
I think scales probably came about because in past days these devices had two pans (scales).
In one pan you would place a known weight (2Kg for example) and then you would add a substance like sugar until the pans/scales balanced.
From this you would know that you had measured out the correct amount of sugar desired i.e. 2 kg.
Today most devices have one pan /scale
hence the singular form.
ell.stackexchange.com/users/57606/user242899
I agree that this usage is very confusing.
Here is a sloppy collage I made to try and explain the difference.
All of the pictures here could be called "a scale" in a general sense.
For example, if I said, "Weigh it on a scale!"
any of these tools would be appropriate.
However, the top row here depicts some scales or a set of scales
If the weighing tool has two or more parts to balance (like the top row), you can refer to it as the scales or a scale .
The middle image is the plural form of scales, while the scales in the first image could be considered a noun with no singular form .
The bottom row depicts a specific scale .If
you're in the gym, the more common usage is the version without the -s, scale : "Step on the scale in the corner."
For context, I am a young, Midwestern American.
Older folks or other countries might use scales instead.
ell.stackexchange.com/users/38613/Maggie
Of the top 10 digital kitchen scales on Amazon UK today, 5 describe themselves as "scales", 1 describes itself as "scale", and 4 hedge their bets and use both terms.
The numbers are exactly the same for the top 10 bathroom scales.
Anecdotally, I would say that the UK is undergoing a shift from scales to scale, partly generational.
"Scale" sounds odd to my British English ears, but it is increasingly heard and read.
Neither is wrong in British English usage, but using "scales" in the UK is still safer in that hardly anyone (yet) will regard it as wrong whereas the reverse isn't the case.
ell.stackexchange.com/users/118183/Stephen Dawson
According to the Global Corpus of Web-based English, both forms are used in North America and Australia, with "scale" being slightly preferred; but "scales" is strongly preferred in the UK, Ireland, and New Zealand.
Looking for "scale (noun)" near a form of "weigh"
, I get US: 36;
CA: 28; GB: 15
; IE: 8; AU: 10; NZ: 1. but for "scales (noun)" near a form of "weigh", I get: US: 32; CA: 21; GB: 50;
IE: 21;
AU: 10; NZ: 10.
Certainly I (BrE speaker) would always say "scales" (and use a plural verb and pronouns).
ell.stackexchange.com/users/1780/Colin Fine
My daughter and I have just had the same argument.
It may have a generational element to it as well as regional.
Scales are in the category of nouns that, because of having, or originally having, two parts, took on plural usage.
Scissors, shears, and pliers fall in this category.
So do pants, trousers, slacks, even culottes and shorts.
We even speak of them as plural: a pair of pants when we are referring to a single garment.
Interestingly, when they are used as adjectives, they become singular: a pant suit; a scissor cut.
ell.stackexchange.com/users/88262/Texas mama
When referring to Weighing scale/s that for weighing things or people in gym for example, then what's correct? scale or scales or both correct?   I am asking it right after looking at the entry in  Cambridge dictionary  and I got confused because it is not clear there.
Weighing scale or scales?
ell.stackexchange.com
<singular-vs-plural>
ell.stackexchange.com/questions/150461
ell.stackexchange.com/users/12430/Judicious Allure
 According to the Global Corpus of Web-based English, both forms are used in North America and Australia, with "scale" being slightly preferred. However, "scales" is strongly preferred in the UK, Ireland, and New Zealand. In North America and Australia "scale" is slightly preferred, but "scales" is strongly preferred in the UK, Ireland and New Zealand.
In North America and Australia, both forms are used, whereby "scale" is slightly preferred, according to the Global Corpus of Web-based English, but "scales" is strongly preferred in the UK, Ireland and New Zealand.