EC to PPM Calculator

PPM is not measured directly. A meter reads electrical conductivity and multiplies it by a fixed conversion factor to show PPM. Brands chose different factors, so the common scales are 500 (Hanna and many US meters), 640 (Eutech) and 700 (Truncheon). The same EC therefore shows a different PPM on each scale.

Match the scale to your own meter so readings line up with your nutrient chart. If a feeding chart quotes PPM, find out which scale it assumes, because 1000 ppm on the 500 scale is EC 2.0 while 1000 ppm on the 700 scale is only about EC 1.43.

PPM equals EC multiplied by the scale factor, and EC equals PPM divided by the same factor. So EC 2.0 on the 500 scale is 2.0 times 500, which is 1000 ppm. Results are rounded to two decimal places.

EC is entered in millisiemens per centimeter (mS/cm), the usual range for hydroponic feeds. If your meter shows microsiemens (uS/cm), divide that figure by 1000 first, so 1500 uS/cm becomes 1.5 mS/cm.

Yes. Select the PPM to EC radio button, enter your PPM reading, and pick the matching scale. The tool divides by the factor and shows the EC in mS/cm, which is handy when a recipe lists PPM but your controller wants EC.

The engine only accepts a positive value, so a blank, zero or negative entry shows a short prompt to enter a positive number instead of a result. Enter any value above zero and the cards reappear.

No. These are general conversion guidelines. True dissolved solids depend on the specific salts in your mix, and temperature shifts EC, so treat the number as a planning aid and trust a calibrated, temperature-compensated meter for critical work.

Target strength varies by crop and growth stage, so follow your nutrient brand and crop guidance. This tool only converts between EC and PPM. It does not recommend a feeding strength.

Yes. The conversion runs entirely in your browser with plain arithmetic. Nothing you type is uploaded or stored, so you can use it offline once the page has loaded.