Extech ExStik II PH100
#5 in Pen testersFull review
A pen with a flat electrode for checking cheese, meat, paper or wet surfaces as well as liquids.
Amazon $129.50$129.50
The Extech ExStik II PH100 is the better ph meter overall, rated 3.6 to 3.3. The Extech ExStik II PH100 leads on accuracy and features. The Ohaus Starter ST20 wins on price. The Ohaus Starter ST20 costs $24.88 less ($104.62 vs $129.50).
Prices were last checked November 9, 2026. Product prices and availability are accurate as of that date and are subject to change; the price and availability shown on Amazon or the retailer's site at the time of purchase apply. As an Amazon Associate we earn from qualifying purchases.
Ohaus Starter ST20
#7 in Pen testersFull review
A pen tester from a lab-balance maker, for classrooms and labs buying Ohaus gear. The Apera PH60 is more accurate for less.
Amazon $104.62$104.62
Which should you buy?
- Choose the Extech ExStik II PH100 for accuracy (±0.01 pH vs ±0.05 pH) and features (replaceable probe, automatic temperature compensation, waterproof, stores readings vs replaceable probe, automatic temperature compensation, waterproof (IP67)).
- Choose the Ohaus Starter ST20 for price ($104.62 vs $129.50).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every pen testers ph meter; a clear win is highlighted. How we rank explains each one.
| Factor weight | Extech ExStik II PH100 | Ohaus Starter ST20 |
|---|---|---|
| Overall rating | 3.6/5 | 3.3/5 |
| Accuracy 30% | 81 ±0.01 pH | 38 ±0.05 pH |
| Calibration 15% | 50 calibration points not published (neutral score used) | 85 3-point calibration |
| Features 20% | 90 replaceable probe, automatic temperature compensation, waterproof, stores readings | 80 replaceable probe, automatic temperature compensation, waterproof (IP67) |
| Extra readings 10% | 0 pH and temperature only | 0 pH and temperature only |
| Price 15% | 67 $129.50 | 76 $104.62 |
| Warranty 10% | 0 warranty not published, scored as none | 0 warranty not published, scored as none |
Specifications
| Extech ExStik II PH100 | Ohaus Starter ST20 | |
|---|---|---|
| pH measurement | ||
| Accuracy | ±0.01 pH | ±0.05 pH |
| Resolution | 0.01 pH | 0.01 pH |
| Range | 0 to 14 pH | 0 to 14 pH |
| Calibration | - | 3-point |
| Temperature compensation | Yes | Yes |
| Other readings | ||
| Conductivity (EC/TDS) | No | No |
| ORP | No | No |
| Salinity | No | No |
| Build | ||
| Replaceable probe | Yes | Yes |
| Waterproof rating | Waterproof | IP67 |
| Stored readings | 15 readings | - |
| Battery life | - | 200 hours |
| Weight | - | 110 g |