Measurement.define(:'in³') do |unit|
  unit.alias :in3, :'in^3', :'in*in*in', :'cubic inch', :'cubic inches'
  unit.convert_to(:'acre ft') { |value| value / 75_271_680.0 }
  unit.convert_to(:yd3) { |value| value / 46_656.0 }
  unit.convert_to(:ft3) { |value| value / 1_728.0 }