Use 'I tell you' to really stress what you're saying, as if underlining it.

Stress Emphasis

'I tell you' adds a friendly, chatty tone to your speech, making it less formal.

Conversational Tone

It's suitable when you're sharing a personal, strong opinion or conviction.

Express certainty or assert the truth of your statement by adding 'I tell you.'

It helps to clarify a misunderstanding or insist on your honesty.

Sometimes it conveys frustration or impatience when repeating oneself.

By prefacing with 'I tell you,' you signal you're about to share news or information.

Good for starting a sentence where you're giving a friend or family an update.

It grabs the listener's attention, making them focus on the forthcoming information.