How much is considered "normal wear and tear" for carpet?

[Carol Bloom]

Hello BP community!

I'm Carol I need your help how do you calculate how much to charge for "normal wear and tear" on carpeting. I have a tenant moving out, they have been with me for 5 years the carpet was not new when they moved in but they have a dog paid $250 pet deposit. When I went to visit the house with the realtor because I'm going to sell it, I noticed lots of pee spots and dirt spots. The tenant said they will have the carpet cleaned before they move out but of course they are in denial of how the spots got there. I will be replacing the carpet but I'd like to get a formula to calculate what's normal vs what's the tenant expense if any to pay?

Thanks!