The year of manufacture of well-known brand name pianos can often be calculated from its serial number. On an upright piano it is usually printed on the frame or soundboard around the top close to the top lid. On a grand piano it is usually printed on the soundboard underneath the strings or on the frame near the tuning pins. It is usually between a 4 and 6 digit number.
If you email firstname.lastname@example.org with your pianos serial number and make, we will try to look up the year for you. Failing that, photographs of the piano both inside and out will enable us to hazard a guess.