A size 27 in jeans is a women’s size 4 to 5 in U.S. sizes. The 27 is the waist measurement. Jean sizes vary considerably from country to country and sometimes by brand or style.
There are two jean sizing scales in the United States. Typically, designer or premium brands use the waist measurement-derived sizing scale. To determine true jean size by waist, the smallest part of the waist should be measured.
In the UK, Australia and New Zealand, a size 27 translates to a size 9. In Italy, it is a size 40/42. In France, it is a size 36/38. In Japan, it is a size 7/9. In Denmark, a size 27 is between a size 32 and 34.