How much does it cost to replace battery for iPhone 11?

You can get an estimate here:

iPhone Battery Repair & Replacement - Apple Support

In the U.S., it's $89 dollars. If you're not planning on replacing the phone this year, it's absolutely worth it.

Buying a used phone, unless it's from someone you know and trust is a big gamble. Getting the battery replaced by someone other than Apple or an Authorized Apple Service Provider is also a gamble as they will most likely not be using a genuine battery.

jerold146 wrote:

My battery is 80% now then iwant to back in 100%

Please read the support article linked in the reply immediately above your post.

If you ask at your nearest Apple store, you will get the answer.

My battery is 80% now then iwant to back in 100%

It costs a decent amount if you don’t want to go to the nearest Apple Store then try eBay or Amazon ( the prices change alot so I’m not sure the exact amount )if you can’t find something fitting or affordable in my experience it should be cheaper just to buy a brand new older phone Maby a 10 or 9 because the people who install the batteries ( in less your a technician ) charge a lot plus after the gen 6 I feel like they haven’t changed that much…

hope this helps

My battery is 80% now then iwant to back in 100%

Replace your old battery with a new battery. This is the only way to do what you want.

jerold146 wrote:

My battery is 80% now then iwant to back in 100%

That is not possible. It would violate the laws of physics.

Not exactly. Not if you can create negative entropy.