What is the total System GAIN of olimex EKG/EMG Shield?

[brianzkee]

I need this parameter to calculate the actual ECG voltage. I cannot identify the gain in the datasheet eagle schematics, there's too many gain also confused with the op-amp regulated Gain. Help me! I need this value.

[Badreddinez]

The ADC of Arduino maps the voltages from 0-5V to 0-1024.
In case if there are not electrodes, you will notice that there is an offset of 300.

In order to find your Voltage, you need to subtract the offset and multiply by the corresponding resolution of the ADC mapped to the voltage.

Let me know if you need further clarification.