What is the average cost for 3 dogs on a drop in visit?

The rate will highly depend on your area, but I’ll share my rate breakdown:

$17 drop-in for one dog + 2x$5 additional dog fee = $27 per 30 minute drop-in.

There may be an additional fee of $5 to extend to an hour (bringing the total to $32) depending on how much pee/poop there is to clean up. And an additional $5 if they’re under 1 year of age.

Rates and additional dog rates are different from city to city and state to state, there really isn't an average. Many sitters charge $5 to $10 for each extra pet, some charge more.

$24 per 30 minute drop in visit + $5 for each add'l dog (i.e., 3 dogs total) x 3 visits per day = $34 for each visit ($24 for 1 dog $5 for each additional dog) x 3 visits a day would be $102 per day. The visits would likely be longer than the normal 30 minutes due to there being the 3 dogs but that would be understandable to give each dog plenty of time and TLC during the visit.

I charge $15 per visit with a $6 additional pet fee. If there were 3 pets, I would only charge the drop in fee + 1 additional pet fee. Not necessary (for me) to add $6 per pet since i am already there.

Since you don't appear to own the three terriers, I assume you want to know how much to charge someone for providing this service. House sitting or drop-in? You can take a look at what others in your area charge and you should pay particular attention to whether they charge for additional dogs because you don't currently have that in your rate table for drop-ins, house sitting or even boarding in your home. Rather generous IMO, but that's your call.

Obviously you are looking for some guidance on how much to charge. Give Rover a call. They might be able to give you some numbers. I can't imagine they wouldn't be able to pull up averages from their system.

I would do a search of sitters in your area to see their rates and that should give you the average. As Walt said, it depends on the area. I would make sure that, when you contact sitters, you mention they might be cleaning up accidents in the house. Picking up poop that the dogs do outside during the walk or visit (or even pee or poop they do in the house when the sitter is there) is generally part of the drop in or walk; however, I'm not sure how common it is to have to clean up messes in the home that occurred between visits. I would likely charge more, because it's not "normal" for drop in or walks, at least not in my experience. Good Luck!