We have investigated the influence of sample size on the calibration o
f a vibrating sample magnetometer. As expected, when measurements and
calibration are carried out on samples with the same shape the results
agree within the experimental uncertainty. For two cylindrical sample
s of nickel, one with length and diameter 2.0 and 2.0 mm, and another
with 5.3 and 1.0 mm respectively, the magnetometer signal varies with
the length, in good agreement with numerical calculations.