The most important thing is you feel confident in what you achieved. 3500 calories for every pound, one hour of fast walking is 500 calories on average, 1 hour of walking is 2.5-4 miles depending on your strength.
You do the math ... you walked a very far distance and didn't even realize it.
875-1400 miles
Use the tool below, put your home address in and see where your work actually took you.