by Guest » Sun Mar 19, 2006 9:13 pm
A mile is 1609.344 m
A nautical mile is 1852 m
(both values are exact definitions)
So
1 mph x1609.344 m/mi / 1852 m/n. mi = .868 976 24 knots
From knots to mph, multiply by 1852/1609.344 = 1.150 779 45
(0.87 and 1.15 are good enough for most work)