Bangkok - Chiang Mai - Koh Samui en été

Hi, so glad my story was helpful! I found the sign for the Grand Palace. Here's the photo.
Basically, no tank tops—your shoulders need to be covered. I had a lightweight short-sleeve shirt I wore for temples and linen culottes that barely showed my ankles (I pulled them down over my stomach to gain some length when going through the gates ).

Hi,In reality, these rules apply in all temples, even the most "insignificant" ones. Just because there are no signs in others doesn’t mean it’s morally acceptable to enter dressed "sloppily" (for women or men) by Thai standards. When people do it anyway, most of the time they don’t say anything because they’re shy/modest/hypocritical, but that doesn’t stop them from thinking negatively about us.
Here, if there’s a sign at the entrance to remind people of the rules and enforce them, it’s not just because you’re entering a temple—it’s also because you’re entering the king’s "home," a type of figure you wouldn’t visit dressed like a "slob."

Thanks! 😊

It seems normal to me not to dress "sloppily" in a temple. Unfortunately, some tourists have no respect at all.That said, the sign isn’t very clear about sleeves. Is a short-sleeved t-shirt—so shoulders covered—acceptable, or do you absolutely need long sleeves?

Long sleeves.
Long pants.
Skirts and dresses must fall below the knees, including when sitting or squatting.

Don’t faint if you see, as I have several times, young Thai women in skirts or even short miniskirts praying like everyone else in a temple.
It really puts things into perspective.Practically speaking, my wife usually dresses as she normally does—shorts and a t-shirt—and wears a very light sarong over the top, like the ones you can buy in Thailand. Hers has a gecko printed on it. It covers well, and she doesn’t get as hot as she would in a shirt and pants.
We’ve never had any comments or disapproving looks. That said, it’s a country where people appreciate a smile and respectful behavior in places of worship. Most don’t really care about the rest.The most important temples are ranked as 4th, 3rd, 2nd, and 1st royal class, with the Grand Palace completely in a league of its own at the top of the hierarchy. Here and there, the rules are enforced a bit more strictly—but even then, not by much.
At the Grand Palace, they don’t mess around with protocol.

Thanks everyone for your really detailed replies.