# How fast is ShiftOut

**URL:** <https://forum.arduino.cc/t/how-fast-is-shiftout/369057>\
**Category:** LEDs and Multiplexing\
**Created:** [February 29, 2016, 8:26pm UTC](https://forum.arduino.cc/t/how-fast-is-shiftout/369057 "2016-02-29T20:26:50Z")\
**Posts on this page:** 1\
**Showing post:** 12

<div class="post-metadata">

**Author:** ![PaulRB](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/paulrb/32/216330_2.png) [@PaulRB](https://forum.arduino.cc/u/PaulRB)\
**Post date:** [March 6, 2016, 8:47pm UTC](https://forum.arduino.cc/t/how-fast-is-shiftout/369057/12 "2016-03-06T20:47:48Z")

</div>

> Arnoud:
> 
> - ShiftOut does 1 byte in ca. 150us  
> then SPI does 1 byte in ca. 1us.

Wow, quite a difference. But in practice, just how much difference does it actually make?

What if the the Arduino needs to transfer 1KB? If that data is held in an array in ram, and a for() loop is performed to go thru each byte, what's the timing for shiftOut() vs SPI.transfer() for the 1024 bytes of data?

---

_[View the full topic](https://forum.arduino.cc/t/how-fast-is-shiftout/369057)._