28km2 in UE4?

I want the size of my landscape to be exactly 28km2, but i don`t know how. Please help.

Check out the landscape documentation.

You can size the landscape in unreal unit (cm). So convert 28 km2 to the lengths of a rectangle you’d prefer.

At 1cm wide rectangle, your level would be 28,000,000 unreal units (cm) long.

As a square, each side would be the square root of 28,000,000.