I assume you are looking for the diagonal of the square.

You can use the Pythagorean Theorem:

a² + b² = c²

The sides (legs) are each 1 inch long. They hypotenuse (c) is unknown:

1² + 1² = c²

2 = c²

Take the square root of both sides:

c = √2 ≈ 1.414

Answer:

The diagonal would be about 1.414 inches long