Measuring turntable speed

I have an industrial rpm/ fpm etc etc strobe that I use for work.
It has two modes, contact with various size wheels and strobe non contact very similar to the one Greg linked to.
It is EXTREMELY accurate.
But for a test I also just ordered one of them at $15 so I can compare to my industrial unit.
Will report back.

Phoenix engineering roadrunner.  Great little unit that measures accurately in thousandths after the decimal .xxx
Sota is now selling them singular and in kits with motor and power supply. 

I have a very lightweight paper strobe disc I put atop a spinning record.  I also sometimes find a record that I'm certain possesses a 440 hz A somewhere within it (any recording of a non-period instrument orchestral recording will have one) and then match the pitch on the record to my Seiko metronome's 440 tuning tone.  BTW, it's absolutely shocking how inaccurate my SOTA Sapphire's fine speed adjustment wheels have gotten over the centuries.

KAB speed strobe.

Try RPM Pro. An app for your smartphone. You put the phone on your turntable and the results are really accurate.