Can I say 14 pm in English to mean 2 pm?

Nope. The 24-hour clock obviates the need for "am" and "pm". You would say 14:00, pronounced "fourteen hundred" or "fourteen hundred hours" ("hours" sounds a bit military)..

No. am/pm are not used.

The 24-hour clock is usually used only by the military, airlines, etc.

I never encounter it in conversation.

CliveNo. am/pm are not used.The 24-hour clock is usually used only by the military, airlines, etc.I never encounter it in conversation.

In the UK it used for most transport timetables (trains, buses, etc.).

I was writing a reminder app, asking the users to input a time and remind them. It's much easier to ask the users to input in the format of 24-hour clock so that they don't have to input the am/pm. But I'm afraid they might input 2 to mean 14 thus setting up a wrong reminder. So I came up with the idea that after inputting the time, there's going to be a label indicating am/pm. i.e. inputting 14 w

CharmYou.e. inputting 14 will display 14 pm, and inputting 2 will display 2 am. I don't know if this is comfortable to native English speakers.

No, "14 pm" is just wrong.

Ok. I'll ask the user to input am/pm, even though all Chinese users are not used to doing this. We usually prefer using 24 clock.

CharmYouOk. I'll ask the user to input am/pm, even though all Chinese users are not used to doing this. We usually prefer using 24 clock.

I don't see a problem with allowing them to input 14. It is just the presentation "14 pm" that is wrong. If you display it as "14:00" or convert to "2 pm" then that would be OK.

Thanks a lot.