A pen tester is the quickest way to check pH: take off the cap, dip it and read. Pens from $55 to $90 read to ±0.1 pH, which suits pools, aquariums and most gardens. Pens with ±0.01 pH accuracy start under $100. Look for a replaceable probe, because the electrode wears out long before the electronics do, and for an IP67 or IP68 rating if the pen will be used over a reservoir.
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.
Full ranking 13
- Apera PC60 pH/EC Tester#1 of 13Full review
A pen that checks pH and nutrient strength together, for hydroponic growers and reef keepers. It is accurate and the probe can be replaced.
Amazon $131.16$131.16±0.01 pH3-pointEC/TDS, Salinity - Apera PH60#2 of 13Full review
The pick for most people who want an accurate pen tester: ±0.01 pH, three-point calibration and a replaceable probe at pen-tester money.
Amazon $79.99$79.99±0.01 pH3-pointNone - Oakton pHTestr 30#3 of 13Full review
A lab-brand pocket tester with a replaceable module, for labs and schools that already stock Oakton parts.
Amazon $136.22$136.22±0.01 pH3-pointNone - VIVOSUN AeroLab pH Pen#4 of 13Full review
A low-cost grower’s pen with a replaceable probe. Its maker publishes little beyond the accuracy claim.
Amazon $65.99$65.99±0.01 pH-None - Extech ExStik II PH100#5 of 13Full review
A pen with a flat electrode for checking cheese, meat, paper or wet surfaces as well as liquids.
Amazon $129.50$129.50±0.01 pH-None - Bluelab OnePen#6 of 13Full review
A connected pen for serious hydroponic growers who want pH and nutrient readings logged to their phone. Most buyers get more for less from the Apera PC60.
Amazon $249$249±0.05 pH2-pointEC/TDS - Ohaus Starter ST20#7 of 13Full 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±0.05 pH3-pointNone - Milwaukee pH58 Max pH/ORP#8 of 13Full review
A pen for pool and water-treatment work that needs ORP as well as pH. For pH alone, cheaper pens are as accurate.
Amazon $219.65$219.65±0.05 pH2-pointORP - Apera PH20#9 of 13Full review
A cheap, waterproof pen for pools, aquariums and drinking water. Pick it when 0.1 pH is close enough.
Amazon $56.65$56.65±0.1 pH3-pointNone - Hanna pHep 5 HI98128#10 of 13Full review
A well-made pocket tester from a lab brand, for anyone who already uses Hanna buffers and electrodes. The Apera PH60 does more for less.
Amazon $179.99$179.99±0.05 pH3-pointNone - Milwaukee pH55 Pro#11 of 13Full review
A low-cost pen with a replaceable electrode, for pools, gardens and aquariums. The Apera PH60 is more accurate for a little more.
Amazon $77.90$77.90±0.1 pH2-pointNone - Bluelab pH PenPlus#12 of 13Full review
The Bluelab pH Pen with a replaceable probe and a longer warranty, for growers who want a pen that lasts. Pick the Apera PH60 if you need finer resolution.
Amazon $115$115±0.1 pH2-pointNone - Bluelab pH Pen#13 of 13Full review
A simple, tough pen for growers checking nutrient pH. The PenPlus costs a little more and adds a replaceable probe.
Amazon $89.95$89.95±0.1 pH2-pointNone
