How to convert raw values to voltage?

For TGAT-based hardware devices (such as TGAT, TGAM, MindSet, MindWave, and MindWave Mobile), the formula for converting raw values to voltage is:

[ rawValue * (1.8/4096) ] / 2000

This is due to a 2000 gain, 4096 value range, and 1.8V input voltage. The unit is V.

The ECG/EKG raw values from CardioChip/BMD10X-based devices must use following conversion:

(rawValue * 18.3) / 128.0

This is due to a 128 gain, 16 bit digital signal. The unit is uV.

Please note the gain on actual hardware may be slightly off from 2000x (maybe +/- 5%?), but unless you need to make ultra-sensitive measurements for some reason, that formula should be good enough.