ARDUINO MEGA2560 is a microcontroller board based on the ATmega2560, which comes preprogrammed with a bootloader that allows user to upload new code to it without the use of an external hard programmer.
A frequent request for this device is the dimension drawing of the board; however, there is no manufacturer created drawings available to provide. Fortunately, some makers have created a detailed technical drawing of the Mega 2560, as shown below.
source: ARDUINO Blog Nice drawings of the Arduino UNO and Mega 2560