1. I regret
I regret the delay / I regret the oversight
2. I'm (so / very / terribly) sorry.
3. I owe you an apology
4. How stupid / careless / thoughtless of me.
5. Pardon (me)!
6. That's my fault.
7. Sorry. It was all my fault.
8. Please excuse my ignorance
9. Please don't be mad at me.
10. Please accept our (sincerest) apologies.
Making a formal or serious apology
If you make a serious mistake with a friend, loved one, or coworker, you shouldn’t use casual language to apologize. Try a more formal apology, such as:
1. I'd like to apologize.
2. I want to apologize.
3. I owe you an apology.
4. I wanted to tell you I’m sorry.
Doubts on this article