Milwaukee PH Meter / soil Meter MW101

Reads acidity to two decimals, accurate to 0.02 pH. For anyone who wants to steer more sharply than one decimal allows.

The Milwaukee MW101 reads 0.00 to 14.00 pH at a resolution of 0.01 and an accuracy of ± 0.02. Manual two-point calibration, manual temperature compensation from 5 to 50 °C, and a replaceable MA918B/1 double-junction electrode.

Resolution or accuracy: which number tells you what?

These two get confused constantly, and the difference decides whether an extra decimal is worth anything to you.

Resolution is how finely a meter can display a value. A resolution of 0.01 means the screen can show 6.04 rather than only 6.0.

Accuracy is how close that value is to reality. An accuracy of 0.02 means a reading of 6.04 actually sits somewhere between 6.02 and 6.06.

Why that matters: a meter with high resolution and poor accuracy lies convincingly. Such a screen shows 6.04 while the true value might be 5.8. The extra decimal makes the number more believable without making it better, that is false precision, and it is a reason not to shop on decimals alone.

On this meter the two are matched: 0.01 resolution at 0.02 accuracy. Here the second digit genuinely means something.

Do you need it? In soil, no. There the medium's buffering is larger than the difference between 6.0 and 6.05. In hydroponics and rockwool, yes: there is no buffer, acidity drives uptake directly, and a movement of 0.05 a day tells you something is shifting: a one-decimal meter only shows that once it has already drifted 0.1.

Technical Specifications:

• pH range: 0.00 to 14.00 pH
• Resolution: 0.01 pH
• Accuracy: ± 0.02 pH
• Calibration: manual, 2 points
• Temperature compensation: manual, 5 to 50 °C
• Electrode: MA918B/1, replaceable, double junction
• Battery: 9V, approx. 300 hours continuous use
• Dimensions: 145 x 80 x 40 mm
• weight: 220 g

Frequently asked questions

Is this a soil meter?
The meter is intended for liquid. To measure directly in soil or coco you need an electrode built for it: an ordinary glass electrode either breaks in a medium or reads unreliably.

Will I notice the difference from a one-decimal meter?
In hydroponics and rockwool: yes, you spot drift earlier. In soil: barely, because the medium buffers those small differences away.

Why manual temperature compensation on such an accurate meter?
Because under stable conditions it barely matters. Measure at roughly the same temperature and set it correctly once, and the correction is as good as automatic.

How often should I calibrate for that accuracy?
More often than with a one-decimal meter. If you want to trust 0.02, weekly calibration with fresh buffer is a sensible habit.