There are various ways: the one(s) you choose will depend upon your resources and your need/desire for accuracy. For instance, and in no particular order:
1. Speed and distance monitor. 2. Map and bit of string after the run. 3. Map and cunning little wheel device after run. 4. Drive round in the car and measure it. 5. Ride round on a bike and measure it. 6. Pedometer. 7. Carry a walking GPS. 8. Force someone else to do any combination of the above for you. 9. Pray for the answer :-) 10. Estimate it based on time taken and effort expended. 11. etc, etc
Comments
There are various ways: the one(s) you choose will depend upon your resources and your need/desire for accuracy. For instance, and in no particular order:
1. Speed and distance monitor.
2. Map and bit of string after the run.
3. Map and cunning little wheel device after run.
4. Drive round in the car and measure it.
5. Ride round on a bike and measure it.
6. Pedometer.
7. Carry a walking GPS.
8. Force someone else to do any combination of the above for you.
9. Pray for the answer :-)
10. Estimate it based on time taken and effort expended.
11. etc, etc
I hope something here helps :-)