I've got a few tuners, a very old non chromatic tuner (with an analogue VU style needle indicator); the chromatic tuner built into my Zoom B9.1 effects unit and I've also, for fun, been trying a free Android app on my phone; seems to work quite well...
https://play.google.com/store/apps/details?id=com.bork.dsp.datuna&hl=en_GB