The Camera & Imaging Product Association (CIPA) is an organization that conducts performance testing on photographic equipment and provides standard measurement results. Nikon Inc. uses the CIPA Standard when providing information on the “shots per charge” battery information for its cameras.
Example: A Nikon D3S equipped with an AF-S NIKKOR 24–70mm f/2.8G ED lens, captured 4,200 images when measured at 23 °C/73.4 °F (±2 °C/3.6 °F) under the following test conditions: lens cycled from infinity to minimum range and one photograph taken at default settings once every 30 seconds. Live view not used.
Real life results will vary depending on factors such as temperature, use conditions and the number of times the battery is recharged.