When is the sun going to explode?

The Sun is not going to explode like a supernova. It’s too small for that.

What will happen instead:

• In about 5 billion years, the Sun will run low on hydrogen in its core.
• It will swell into a red giant.
• Later, it will shed its outer layers and end up as a white dwarf.

So the short answer is: never as an explosion, but it will change dramatically over billions of years.