What about speak and talk?

They are about the act of speaking rather than the words. Speak is slightly more formal and used for languages, she speaks Portuguese, while talk implies conversation: we talked for an hour. Neither takes reported words the way say and tell do.

Why does “tell the time” exist if tell needs a person?

Because tell there means distinguish or work out, not communicate, the same sense as tell the difference and I can’t tell if he’s joking. It is a separate meaning that happens to share the word, so it does not undermine the rule.

Is “say to me” ever preferable to “tell me”?

Occasionally, for emphasis or contrast: don’t say it to me, say it to her. In ordinary sentences tell me is more natural, and say to me can sound stilted, but it is never wrong, which is more than can be said for say me.

Which one to useA2

Say vs tell

The short answer

Tell is followed straight away by the person: tell me, tell her, tell the police. Say is not: you either say something with no person at all, or you say it to someone. If the next word names a person, the verb is tell.

At a glance

Say or Tell?

Compare	SayNo person after it, or “to” first.	TellA person comes immediately after.
Followed by a person	Only with to: say to me	Directly: tell me
With no person	Normal: she said nothing	Not possible on its own
Direct speech	“I’m leaving,” she said.	Not used for quoting
Instructions	Not used	tell someone to do something
Fixed phrases	say sorry, say a prayer, say hello	tell a story, tell the truth, tell a lie, tell the time
Typical error	say me → wrong	tell to me → wrong

How to choose

Ask these, in order

1
Is the next word a person?
Tell. No preposition, no delay.
Tell me what happened.
Person immediately after the verb.
2
Is there no person in the sentence?
Say.
She said she’d call back.
No recipient named.
3
Do you want to name the person but use say?
Add to. Say to me is correct, if slightly formal.
What did he say to you?
Say plus to plus person.
4
Are you quoting the exact words?
Say. Tell does not introduce direct speech.
“We’re closed,” she said.
Never “she told”.

Side by side

Each one, in full

Say

When to use say

No person after it, or “to” first.

Say reports words, with or without a listener. Without one it is completely regular: he said nothing, she said it was fine, what did you say? With one, it needs to: say it to her face.

It is also the verb for quoting. Direct speech in English takes say almost exclusively: “I’ll think about it,” he said, and tell cannot be substituted there at all.

He didn’t say why he was late.

No person mentioned.

Say hello to your parents for me.

A fixed phrase with to.

She said that the office was closed.

Reported speech, no listener named.

NBAdd a listener and you must switch: she told me that the office was closed.

Tell

When to use tell

A person comes immediately after.

Tell requires a person, and that person comes straight after the verb. Tell me, tell him, tell your manager. Without a person, tell only survives in fixed expressions: tell the truth, tell a lie, tell the time, tell a story.

It is also the verb for instructions, with an infinitive: she told me to wait. Say cannot do this: she said me to wait is not English, which makes tell the default for reported commands.

Did you tell her about the meeting?

Person, then about.

He told us to come back later.

An instruction.

I can’t tell the difference.

A fixed phrase where tell means distinguish.

NBSame verb, unrelated meaning, worth knowing so it does not confuse the rule.

Mistakes to avoid

What learners actually get wrong

She said me she was tired.
She told me she was tired. / She said she was tired.
Say cannot take a person directly. Both fixes are correct English, one names the listener, the other does not, but the hybrid is not, and it is the commonest error with this pair.
He told to me the news.
He told me the news.
Tell takes the person with no preposition. Adding to is the mirror image of the previous error, and it usually comes from over-correcting it.
She said me to wait.
She told me to wait.
Instructions with an infinitive take tell. Say has no version of this pattern at all, so there is no way to repair the sentence without changing the verb.
Can you tell that again?
Can you say that again?
With no person and no fixed phrase, tell has nowhere to stand. Say is the verb for repeating words.

Questions

Asked and answered

What about speak and talk?: They are about the act of speaking rather than the words. Speak is slightly more formal and used for languages, she speaks Portuguese, while talk implies conversation: we talked for an hour. Neither takes reported words the way say and tell do.
Why does “tell the time” exist if tell needs a person?: Because tell there means distinguish or work out, not communicate, the same sense as tell the difference and I can’t tell if he’s joking. It is a separate meaning that happens to share the word, so it does not undermine the rule.
Is “say to me” ever preferable to “tell me”?: Occasionally, for emphasis or contrast: don’t say it to me, say it to her. In ordinary sentences tell me is more natural, and say to me can sound stilted, but it is never wrong, which is more than can be said for say me.