Method for determining a field map in an MR system comprising a movable patient support, stationary shim coils, and movable Coilshims, the method comprising: - providing a first resulting field map B ( x,y,z,SHIM,TP 1), corresponding to a first position TP1 of the patient support, including information about a magnetic field distribution in an homogeneity volume including an examination volume of the MR system when the movable patient support is located at the first position TP1, wherein x, y, z correspond to coordinates in a device coordinate system, wherein SHIM corresponds to an overall shim condition; - providing a stationary field map B DCS ( x,y,z,SHIM stat) including information about a magnetic field distribution in the homogeneity volume, which is independent of the position of the movable patient support, wherein SHIM stat denotes a shim contribution by the stationary shim coils; - determining a position dependent field map B table ( x, y, z, SHIM move, TP 1) including information about a magnetic field distribution in the homogeneity volume mainly influenced by a position of the movable patient support using the stationary field map and the first resulting field map, wherein SHIM move denotes a shim contribution by the movable Coilshims, wherein determining the position dependent field map comprises calculating a difference between the first resulting field map and the stationary field map using the relation B table ( x,y,z,SHIM move, TP 1) = B ( x,y,z,SHIM,TP 1) - B DCS ( x,y,z,SHIM stat); and - determining a second resulting field map in the homogeneity volume when the movable patient support is located at a second position TP2 different from the first position TP1, using the stationary field map and the position dependent field map; wherein the second resulting field map is determined using the position dependent field map, wherein the position of the position dependent field map is shifted relative to the stationary field map by the displacement (d) of the movable patient support along the z-coordinate, wherein the second resulting field map is determined according to the relation B x, y, z, SHIM, TP 2 = B DCS x y z SHIM stat + B table x, y, z − z TP 1 + z TP 2, SHIM move, TP 1, wherein B(x,y,z,SHIM,TP2) is the the second resulting field map, B DCS ( x,y,z,SHIM stat) the stationary field map, B table ( x,y,z-z TP 1 + z TP 2, SHIM move, TP 1) is the position dependent field map shifted by the displacement d = z TP 2 - z TP 1, wherein z TP 2 corresponds to the z-coordinate of the second position of the movable patient support and z TP 1 corresponds to the z-coordinate of the first position of the movable patient support, and the overall shim condition SHIM = (SHIM stat, SHIM move) consists of a contribution SHIM stat by the stationary shim coils, and a contribution SHIM move by the movable Coilshims, which are moved together with the patient support. - providing a first resulting field map B ( x,y,z,SHIM,TP 1), corresponding to a first position TP1 of the patient support, including information about a magnetic field distribution in an homogeneity volume including an examination volume of the MR system when the movable patient support is located at the first position TP1, wherein x, y, z correspond to coordinates in a device coordinate system, wherein SHIM corresponds to an overall shim condition; - providing a stationary field map B DCS ( x,y,z,SHIM stat) including information about a magnetic field distribution in the homogeneity volume, which is independent of the position of the movable patient support, wherein SHIM stat denotes a shim contribution by the stationary shim coils; - determining a position dependent field map B table ( x, y, z, SHIM move, TP 1) including information about a magnetic field distribution in the homogeneity volume mainly influenced by a position of the movable patient support using the stationary field map and the first resulting field map, wherein SHIM move denotes a shim contribution by the movable Coilshims, wherein determining the position dependent field map comprises calculating a difference between the first resulting field map and the stationary field map using the relation B table ( x,y,z,SHIM move, TP 1) = B ( x,y,z,SHIM,TP 1) - B DCS ( x,y,z,SHIM stat); and - determining a second resulting field map in the homogeneity volume when the movable patient support is located at a second position TP2 different from the first position TP1, using the stationary field map and the position dependent field map; wherein the second resulting field map is determined using the position dependent field map, wherein the position of the position dependent field map is shifted relative to the stationary field map by the displacement (d) of the movable patient support along the z-coordinate, wherein the second resulting field map is determined according to the relation B x, y, z, SHIM, TP 2 = B DCS x y z SHIM stat + B table x, y, z − z TP 1 + z TP 2, SHIM move, TP 1, wherein B(x,y,z,SHIM,TP2) is the the second resulting field map, B DCS ( x,y,z,SHIM stat) the stationary field map, B table ( x,y,z-z TP 1 + z TP 2, SHIM move, TP 1) is the position dependent field map shifted by the displacement d = z TP 2 - z TP 1, wherein z TP 2 corresponds to the z-coordinate of the second position of the movable patient support and z TP 1 corresponds to the z-coordinate of the first position of the movable patient support, and the overall shim condition SHIM = (SHIM stat, SHIM move) consists of a contribution SHIM stat by the stationary shim coils, and a contribution SHIM move by the movable Coilshims, which are moved together with the patient support.