when using the calulator how do I estimate repairs without access to the home?

for instance is there a formula that I can use to guess-timate exterior paint pertaining to the size of the home?

is there a rule-of-thumb for carpet?

Any help appreciated.

If you're wholesaling the house, you don't need to know an exact number. Most rehabbers are going to get estimates anyway or make their own estimates. Your goal should be to get within the ballpark of where they will likely be. 

There are a couple of repair estimate calculators for specific jobs you can find online just by searching for them on Google. I'm not sure exactly how you manage your business or do your deals. I tend to not go to houses until we are generally agreed on price and/or terms. I usually take what the owners tell me with a grain of salt, especially if they haven't sent me pictures or anything.

I generally categorize the condition of the property (e.g. Not Bad, Bad, Horrible) and assign a multiple based on the category. I then take this multiple and multiply it by SQFT. For example, if a house is Not Bad (e.g. just needs fresh paint, carpet, fixtures) and was 1000 SQFT I would generally just estimate repairs at around $10,000 or $10 multiplier x 1000 SQFT. 

For older houses (generally anything built before 1980) I would add that if the house is in "OK condition" I'll still will take on a 50% multiplier. This is because older houses tend to have more hidden problems. 

Like I said, I do this just to get a ballpark figure. If the owner is wanting say $200,000 and my numbers are coming out around $100,000 then that's a drive I probably will not make.