This is Chinese Size,the standard was based on "Foot Length",not "Shoes Length", not "Insole Length".
In China,only correct"Foot Length" can help you buy correct size.
If you measure Shoes Length, you will order wrong size.
If you measure Insole Length, you will order wrong size.
If your foot is wide or fat than usually,you can buy bigger size.
Size 45 fit for Foot Length 27.5 centimetre.
Size 46 fit for Foot Length 28 centimetre.
Size 47 fit for Foot Length 28.5 centimetre.
Size 48 fit for Foot Length 29 centimetre.
Size 49 fit for Foot Length 29.5 centimetre.
Size 50 fit for Foot Length 30 centimetre.
Size 51 fit for Foot Length 30.5 centimetre.
Size 52 fit for Foot Length 31 centimetre.