A pycnometer is a glass beaker of defined volume. It is weighed without sample (M1), then filled with the sample and weighed again (M2). The difference between M1 and M2 (=Mass of the sample) divided by the volume of the beaker is the density of the sample.

Advantages:	Disadvantages:	Main applications:
simple method	breakable glassware	educational: what is density, how to measure density
relatively inexpensive instrument	long and difficult thermostating	production control: where more precision is required
inexpensive instrument	density must be calculated (some balances include this calculation)	analytical labs: where GLP is not required
special instruments with direct readings in Alcohol%, Sugar% (BRIX) or other density related values available	operator dependent readings, therefore limited accuracy	not suitable for expensive samples (large volume required).
(*) if no thermostating required	no measurement protocol (not suitable for GLP)
	large sample volume required