The Great Circle Distance Calculator
Enter Degrees Minutes and Seconds with one space between like this 60 30 10. You can enter 60 and it will be assumed to be 60 degrees. if you enter 60 20 it will assumed to be 60 degrees and 20 minutes. If you want to enter 10 seconds enter 0 0 10. You can also enter minutes and seconds as a decimal as in 40.40 minutes.
You can also pick a location from the list-pick below the latitude and longitude. I currently have a Pacific Ocean and a Sea of Cortez list. There may be an Atlantic list some day. The latitude and longitude from the list will only be applied when you change the selection on the list.
This Great Circle Distance Calculator gives an answer in nautical miles. Where as one minute of latitude is equal to one nautical mile. To achieve this I have set the radius of the earth to be 3437.74677078492999 nautical miles and then all results are rounded off to tenths of a mile. Please remember that even if the distance is correct it may not be the route you have to take. This calculator does not take in to account any land you may have to go around to get there. At high latitudes this calculator may not be correct.
DMA charts for the Sea of Cortez are from US Navy surveys done in the late 1800's. I have found from my personal experience that GPS coordinates are usually a mile to a mile an a half east of where you are physically on the paper chart. You should use any latitude and longitude as approximate until you have checked it on your own GPS.