Even if a calculation with water temperatures of 0-40°C / 32-104°Fis possible, the measurement should still be carried out as close as possible to 20°C / 68°F.
Since almost no one has an absolutely accurate indicating thermometer, an additional "thermometer error" can be specified. This can be determined with the help of the Thermometer Error calculator. This does not apply here however to the calibration temperature. So 20°C calibration temperature means a pycnometer calibrated to real 20°C. But it is valid for the measured temperature of the alcohol. So the temperature entered there is the display value of the thermometer.
With the help of the calculator Pycnometer Volume Determination you can determine the exact volume of the pycnometer yourself, if it is not engraved.

General Information about Pycnometers