What is the minimum voltage value that can be measured accurately?

What is the minimum voltage value that can be measured accurately?

If good low thermal construction techniques are used, repeatability of a few nanovolts [10^-9V] can be obtained. To this must be added the accuracy specifications of the instrument. A very good cost-effective solution for low voltage measurement is the 2182. For picovolt resolution and measurements, the 2002 DMM and 1801 Nanovolt Preamp is the most sensitive room temperature digital nanovoltmeter available.