user65: The Arduino boards provide an analog input range of 0V to 5V which translates to 0 to 1023 integer values. The range is determined by the on-board ADC, which in the case of the Uno is a 10 bit ADC (2^10 = 1024). 
Do any of the official boards have a larger (>10 bits) ADC? Do any boards provide a wider range of analog input values?

user168: How much accuracy do you really need? If it's just 1 or 2 extra bits of resolution you are after, you might be able to achieve that with a bit of oversampling.
Basically, you take a ton of readings and average them. It only works if there is at least a few mV of random noise in your signal or in your ADC, and if your input signal bandwidth is low enough to be averaging samples together.
Otherwise, go with a dedicated ADC chip.

user368: AVR-based Arduinos only have 10-bit ADCs, but the ATSAM3X in the Due has 12-bit ADCs. Additionally, it is possible to interface to higher-resolution external ADCs via I2C or SPI.

65: <p>The Arduino boards provide an analog input range of 0V to 5V which translates to 0 to 1023 integer values. The range is determined by the on-board ADC, which in the case of the Uno is a 10 bit ADC (2^10 = 1024). </p>

<p>Do any of the official boards have a larger (>10 bits) ADC? Do any boards provide a wider range of analog input values?</p>
 168: <p>How much accuracy do you really need? If it's just 1 or 2 extra bits of resolution you are after, you might be able to achieve that with a bit of oversampling.</p>

<p>Basically, you take a ton of readings and average them. It only works if there is at least a few mV of random noise in your signal or in your ADC, and if your input signal bandwidth is low enough to be averaging samples together.</p>

<p>Otherwise, go with a dedicated ADC chip.</p>
 368: <p>AVR-based Arduinos only have 10-bit ADCs, but the ATSAM3X in the Due has <a href="http://arduino.cc/en/Reference/AnalogReadResolution">12-bit ADCs</a>. Additionally, it is possible to interface to higher-resolution external ADCs via I<sup>2</sup>C or SPI.</p>
