A brisk walk is about 3 miles an hour, which is faster than a stroll. To get any real health benefits you need to walk over 3 mph for 20 minutes or longer in one stretch. While walking slower or in short bursts has some benefit, you need to get your heart rate up (and burn more calories) for a real cardio benefit.
In 1 hour Men age 17-25 should be able to brisk walk about 8 miles. Men 25-35 should manage about 7.7 miles. Women in the 17-21 age range, comfortably reach 7.8 miles with Women 25-35 achieving 7.5 miles.
Over 35s Men over 35 manage to brisk walk roughly 7.4 miles in an hour. Women over 35 a little less, 7.2 miles.
Over 60s Men over 60, on average brisk walk 7 miles in an hour while Women over 60 brisk walk 6.9 miles.
Safety It goes without saying, consult your doctor before starting any exercise program especially as you get older, if you have health concerns or have not had a recent check up.
Calories Burned based on Time and Weight.
Calories Burned in 2 hours
Weight 100lb:457
Weight 120lb:549
Weight 125lb:572
Weight 150lb:686
Weight 175lb:800
Weight 200lb:914
Weight 250lb:1143
Weight 300lb:1372
Calories Burned in 40 minutes
Weight 100lb:152
Weight 120lb:183
Weight 125lb:191
Weight 150lb:229
Weight 175lb:267
Weight 200lb:305
Weight 250lb:381
Weight 300lb:457
Calories Burned in 40 minutes
Weight 100lb:152
Weight 120lb:183
Weight 125lb:191
Weight 150lb:229
Weight 175lb:267
Weight 200lb:305
Weight 250lb:381
Weight 300lb:457
Calories Burned in 45 minutes
Weight 100lb:171
Weight 120lb:206
Weight 125lb:214
Weight 150lb:257
Weight 175lb:300
Weight 200lb:343
Weight 250lb:429
Weight 300lb:514
Calories Burned in 1 hour 30 mins
Weight 100lb:343
Weight 120lb:411
Weight 125lb:429
Weight 150lb:514
Weight 175lb:600
Weight 200lb:686
Weight 250lb:857
Weight 300lb:1029
Calories Burned in 30 minutes
Weight 100lb:114
Weight 120lb:137
Weight 125lb:143
Weight 150lb:171
Weight 175lb:200
Weight 200lb:229
Weight 250lb:286
Weight 300lb:343