What is the walking time from 77th Street to 57th Street in New York City?

It's about 1 mile (1.61 kilometers), so, assuming you walk at 4 miles an hour (6.44 kilometers per hour) it would theoretically take you about 15 minutes. But you have to keep stopping for traffic lights, so, in reality it would take about 20 to 25 minutes.

In New York City, 17 to 20 street blocks equal a mile (or, 10.5 to 12.5 street blocks equal a kilometer), and 5 to 10 avenue blocks equal a mile (or, 3 to 6.5 avenue blocks equal a kilometer). The length of the avenue blocks varies by neighborhood. On the Upper East Side, it's more like 8 to 10 avenue blocks to a mile (5 to 6.5 to a kilometer), while on the Upper West Side it's more like 5 -- or even 4, in some places -- to a mile (3 or even 2.5 to a kilometer).