How fast is an Arduino?
How fast is an Arduino?


Arduino Uno is based on AVR MCU and run at 16 MHz. Due to the processor architecture it can execute almost 1 instruction per clock cycles (62.5 ns). It uses a simple two step pipeline which may require restart if a branch is taken. There are some instructions such as memory access that take more than one clock cycle. 


  Can an Arduino Uno calculate the time that an assembly instruction will take in nanoseconds, not microseconds? 


It is possible to measure the execution time with a resolution of 4 us with micros(). Please describe what you want to calculate/measure. 

For more details on ATmega328p please see the data-sheet, chap. 6.6 Instruction Execution Timing.