I've been talking a lot about testing the pH of our products as it's so important when we start using different surfactants, conditioners, and active ingredients.

I purchased three pH meters from Amazon. I chose them according to the reviews I saw left on the site. My goal is to calibrate each of them and test them in the calibration solutions to see how well they measure pH.

When you're considering a pH meter, look at at the calibrations it can do. Two is good, three is better.

And look at what the pH levels are for each calibration. It's easy to get pH 4, 7, and 10 calibration solution from Amazon or vendors like Lotioncrafter. If you're using 4.01, 6.86, and 9.18, you'll have to order those powders from the company online somewhere.

Please note, any links you see are not affiliate links. They're intended as information for you about these meters. 
The orange one is the HM Digital pH meter PH-200. (This is my second one as the first one didn't calibrate properly.) It was $100 or so on Amazon. It has an accuracy of +/- 0.1 pH and can also measure temperature in Celsius or Fahrenheit. It can do three point calibrations, pH 4, 7, and 10. It came with two calibration solutions, pH 4 and 7.
(See the link here...)

The yellow one is the Etekcity I purchased from Amazon for around $23. It has an accuracy of +/- 0.05 pH. It can do two point calibrations, pH 4 and 6.86. It came with two calibration powders, pH 4 and 6.86.
(See the link here...)

The red one is ...