How do you write the possessive form of a name ending in s?

[MyBabyIsNameless]

For example, if Thomas wanted a plaque on his bedroom door to indicate it was his room, would it be Thomas's or Thomas'?

It is St Thomas’ hospital in London, but St James’s park.

Thomas'

I don't have any difficulty saying St Barnabas's church and would do so as standard.
My DM was always saying eg ' It's James birthday next week' not realising she was actually saying 'It's Jame's birthday next week',thus giving him a new name. James's she couldn't get her head round but Thomas's was standard for her.

The last time I went near a style guide, it was suggesting s’s for Regular Joes and s’ for VIPs.

So St James’ vs James’s or Jesus’ vs Thomas’s.

Obviously when it’s a thing you use it’s proper name - St Thomas’ Hospital, St James’ Park or whatever.

Ooo
That's right Ineedaholiday!

Thomas’s.

Consider the variant spellings of Liz/Lis (Elizabeth/Elisabeth)

Liz’s
Lis’s

to see why s’ is illogical for possessive singular nouns.

Have to 's' just looks like a spelling mistake.

Thomas's looks best I think. James's, Francis's, Miles's etc.

Lynn Truss and her prescriptivist bullshit can eat my shirt.

Both versions are correct, it comes down to what you prefer.

Both are correct but I much prefer the look of just the apostrophe. My name ends in a double S so it looks ridiculous to add yet another one.

Thomas's looks best I think. James's, Francis's, Miles's etc.

See, I don't like the look of that at all. Too clunky.

I think the reason why the second s looks better these days is that so many people now use an apostrophe to incorrectly denote a plural of a word ending in s (like Facebook status' ) so something like James' looks like someone incorrectly pluralising James, iyswim.

@womanaf
The last time I went near a style guide, it was suggesting s’s for Regular Joes and s’ for VIPs.

So St James’ vs James’s or Jesus’ vs Thomas’s.

Obviously when it’s a thing you use it’s proper name - St Thomas’ Hospital, St James’ Park or whatever.

Its proper name.

Either is correct. Different publications still indicate different preferences here in their style guides, so anyone reading a lot of books/magazines/newspapers which uses one particular option may think the other is wrong, but it's just a relatively arbitrary preference established at some point, and then often 'back-explained' with a retroactive explanation which is just made up. (Style guides which originated at the Oxford press are especially awful for this...)

The inclusion of Greek names isn't very helpful for working out a rule in English - they aren't designed to have apostrophes for the possessive, so whatever we do there is a total made up Hodge podge anyway.

Another editor here. Most style guides I work with would add the final s, with exceptions for certain classical names such as Sophocles. So Thomas’s room, but Sophocles’ plays.

I think this might be quite a recent change in the Chicago Manual of Style (last few years maybe?) - but as far as I can recall, it’s been standard usage in the UK for a bit longer.

I would also put Thomas’s room. I don’t care for the other option even if some think it correct. It just looks wrong.

The rule of thumb is that you only add the extra S if you pronounce it.

So James's room or Thomas's room.

But Claires' room.

But both technically correct 😊

The Room of Thomas

or

Tom's

I prefer

Thomas'

Claire's room? There's no S at the end of Claire.

But Claires' room

??!

Claire doesn’t end in s!

That should be Claire’s room...

I was taught Thomas'. But then I was also taught to add two spaces after a period when typing, which I gather is outdated now. Things change!

Having 3 children whose names end in S, I can confirm that both are grammatically correct, so it's a case of preference.

You’re all being ridiculous.

Any idiot knows it’s Thomaseseses’s’s’s’sss’s”s.

I live in a city housing a public school, fees would make you cry. One of the school houses is labelled Jenkins'. I find it annoying. No apostrophe would be enough, surely?

Thomas' .