For n functions fi in n variables xi, the Jacobian is the determinant of the Jacobian matrix. The absolute value of the Jacobian determinant is a measure of how much area or volume is being stretched or contracted locally. So, for small changes we have
For example, with the usual spherical polar coordinates r,θ,ϕ, the Jacobian determinant equals r2sinθ, showing that the same change in θ contributes to a larger element of volume near this equator (θ = π/2) compared to the north pole (θ = 0), but the longitude φ has no effect on the element of volume. See jacobian matrix.