Multiply the number of hectares by 0.003861 to convert to square miles. For example, if you have 400 ha, multiply 400 by 0.003861 to get 1.54 square miles.
Divide the number of hectares by 258.9988 to convert to square miles. In this example, check your answer by dividing 400 by 258.9988 to get 1.54 square miles.
Verify your answer with an online hectare-to square mile calculator. Enter the number of hectares and press "Go."