All of a Sudden vs. All of the Sudden: Which One Is Correct?

Only one of these expressions is standard English:

All of a sudden → ✔ Correct
All of the sudden → ✘ Incorrect

“All of a sudden” means unexpectedly or very quickly.

1. All of a Sudden

Meaning

All of a sudden is a fixed English expression meaning suddenly, without warning, or very quickly.

Examples (10 total)

1. All of a sudden, it started raining.
2. She stood up, and all of a sudden everyone clapped.
3. All of a sudden, the lights went out.
4. He felt tired all of a sudden.
5. The dog ran off all of a sudden.
6. All of a sudden, the music stopped.
7. She laughed all of a sudden.
8. All of a sudden, the car alarm went off.
9. They became quiet all of a sudden.
10. All of a sudden, I remembered his name.

🧠 Tip:
If it means suddenly, use all of a sudden.

2. All of the Sudden

Meaning

All of the sudden is a grammatical mistake and not used in standard English.

It appears because speakers confuse “a” with “the,” but the expression has never included “the.”

Examples (10 total — incorrect for awareness)

1. ❌ All of the sudden, she screamed.
2. ❌ The lights went out all of the sudden.
3. ❌ He left all of the sudden.
4. ❌ All of the sudden, it got dark.
5. ❌ The noise stopped all of the sudden.
6. ❌ She cried all of the sudden.
7. ❌ All of the sudden, the phone rang.
8. ❌ The room became silent all of the sudden.
9. ❌ He remembered all of the sudden.
10. ❌ All of the sudden, the car started.

🧠 Tip:
If you see “the,” it’s wrong.

3. Quick Comparison Table

4. How to Remember

👉 The phrase always uses a, never the.
👉 Think of it as one sudden moment, not the sudden moment.

Memory trick:
A sudden → one surprising moment
The sudden → doesn’t exist

5. Common Mistakes

❌ Writing “all of the sudden”
✔ Always write “all of a sudden”

❌ Treating it as a literal phrase
✔ It’s an idiom — fixed wording only

Writing More Naturally

Idioms like all of a sudden sound natural only when written correctly. If you want help polishing expressions and avoiding common mistakes, an AI humanizer can smooth out your writing and choose the most natural phrasing automatically.

FAQs

1. Is “all of the sudden” ever correct?

No. It’s always considered incorrect.

2. Do both phrases mean the same thing?

No — only all of a sudden is a real expression.

3. Is “all of a sudden” formal or informal?

It’s commonly used in both casual and formal writing.

4. Can I replace it with “suddenly”?

Yes — “suddenly” is the direct synonym.

Practice: Choose the Correct Version

(Answers are at the end.)

1. __________, the lights went out.
2. She started laughing __________.
3. __________, the dog ran away.
4. He felt dizzy __________.
5. The car alarm rang __________.
6. __________, everything became quiet.
7. The rain started __________.
8. I remembered his name __________.
9. The music stopped __________.
10. __________, she began to cry.

Answers

(Every answer is all of a sudden)

1. all of a sudden
2. all of a sudden
3. all of a sudden
4. all of a sudden
5. all of a sudden
6. all of a sudden
7. all of a sudden
8. all of a sudden
9. all of a sudden
10. all of a sudden