Do I have to replace the toilet gasket if I remove the toilet?

The gasket forms a waterproof seal between porcelain and floor. It would be in your best interests to replace it.

Very well. Are they one size fits all, or do I have to look at it first?

It’s a one size fits all thing. Here’s a helpful video on removing a toilet.

Edit: actually, there’s two types of rings.

Thanks. $100 says I end up being talked into buying a new toilet.

@cockswain, That’s the way of it. You may be repainted the bathroom before it’s all done.

Yes. The seal is compromised after you pull up the toilet.

Just as a fun fact, Thomas Crapper invented the toilet.

One more reason to replace the seal

I had helpful advice but they’ve all been covered. Replace the seal, and what the hell, do the whole bathroom over while you’re at it.

As long as your going to redo the bathroom anyway (and the shower, too, of course), why not recarpet and change the drapes, too? And move the couch a few inches to the left. No, the other left.

Maybe it’s time to move.

There’s no way this job will go as smoothly and quickly as the video.

Seating a toilet is about the only easy thing about toilets, truly easy.

You left out cleaning the windows. Lets do this right.

Seriously, its not that big of a deal, but you will need to replace the O ring at the bottome of the commode. If the O ring is compromised. it may lose its ability to seat properly and leaks will occur.

Do it right the first time and let the person that dropped the pen stick their hand down there and retrieve it.

Same thing happened here with a pair of sunglasses.

Since this is listed under social…
I once decided to install a medicine cabinet in the bathroom. Simple. Knock out the drywall, screw it to studs. Caulk and paint. You start the cut in the drywall by knocking a hole in it with a hammer and then using a saber saw to cut the rectangle. First hit with the hammer – nothing. Next hit – nothing. A little harder this time – boom! – right through the wall and through into the kitchen wall! So now I have to fix the kitchen after putting in the cabinet. Patch the kitchen drywall, sand, patch, sand, patch,... Find a can of paint labeled “kitchen” and paint the hole, and a while I have it out about a dozen small spots: the radiator, the shelf, the other wall, window sill, etc. The paint does not match but I’m sure it will when it dries. Nope. That was the color before we painted 7 years ago. Now I need to repaint the entire kitchen!
The medicine cabinet job was quick but it took days to do the kitchen.
I didn’t change the toilet.