More accurate-- watch or internet map?

If you're using the "follow road" function, then the map will not be accurate. If you're zooming in and carefully plotting the points yourself, it can be very accurate. A 5k I plan to run came in a 3.2 miles on Running Ahead, then came in at dead on 3.10 or 3.11 when I plotted the points myself.

The path measuring tool on Google Earth is probably the most accurate if you take your time with it.

Yes, the accuracy of measurements with google earth is only limited by the accuracy of your clicking. The imagery is more or less scaled perfectly, if you think about it, it has to be for everything to seamlessly line up, without accumulating large errors of great distances.

Map is king, IF you Igor receding where you went. Krueger trust the GPS but it can erors. GPS on flat, open straight roads is basically perfect. In dense woods with lots of winding turns and steep hills you lose accuracy obviously,

OP Here,

The discrepancy came doing four loops in the park, somewhat hilly. I guess I'll go with the internet, although I'm not sure I believe the pace the internet gives me though.

makhloufi n cheese wrote:

If you're using the "follow road" function, then the map will not be accurate. If you're zooming in and carefully plotting the points yourself, it can be very accurate. A 5k I plan to run came in a 3.2 miles on Running Ahead, then came in at dead on 3.10 or 3.11 when I plotted the points myself.

The path measuring tool on Google Earth is probably the most accurate if you take your time with it.

Correct answer.

The maps and the lines drawn on them aren't doing what you think they are doing.

Both are inaccurate but it just depends on what amount of error you can tolerate. Consider that when doing multiple loops the inaccuracies multiply. GPS was designed for aircraft. Differential GPS must be used for accurate ground based measurements. Map accuracy varies quite significantly and can only be used to estimate distances. Longer distances will tend to be more accurate.

This is the most highly accurate method for measuring a course. But even this isn't perfect and for record attempts courses are often set slightly longer than measured to ensure that the full distance is covered.

http://www.usatf.org/Products-/-Services/Course-Certifications/USATF-Certified-Courses/Certify-Your-Course.aspx

Course Measurement and Certification Procedures

Equipment Needed

Jones Course Measuring Device. The Jones Counter is attached to the front wheel of the bicycle and displays “counts” proportional to the number of wheel revolutions. The original Jones Counters were designed so 20 counts = one revolution. Later models had different gear ratios, including 30 counts/revolution and 23.63636… (=260/11) counts/revolution, which is also the ratio of the latest “JR” model Jones Counter. In all versions, a “count” represents approximately 7 to 10 centimeters (3 to 4 inches) on the ground. The “JR” model counter is available at

www.jonescounter.com

. Additional information about acceptable counters can be found on the USATF website at Additional Tools.

Bicycle. A good "ten-speed" (or higher-speed) bike with high pressure tires is best, but any bicycle you are comfortable riding is OK. Refer to the section on "Use of the Calibrated Bicycle" for instructions on how to attach the Jones Counter to your bicycle.

Steel Tape. A 30 meter/100 foot steel tape is best, but a 15 meter/50 foot tape is OK. The steel tape is used to lay out the calibration course and to make adjustments to the course.

Spring Scale. A spring scale, capable of a 50 newton (5 kilograms-force or 11 pounds-force) pull, is needed for the steel tape to be under proper tension. The spring scale need not be a precision instrument; the inexpensive variety sold at sporting goods stores for use by fishermen is OK.

Thermometer. Use a small thermometer to take temperature readings so that steel tape measurements can be corrected for temperature.