EC to PPM (500 Scale) Converter
Hanna meters and most US hydroponic charts use the 500 scale: multiply EC by 0.5. If your meter is a Hanna (or reads "500"), this is your converter.
Calculator
EC to PPM (500 Scale) Converter
Was this calculator helpful?
Your feedback helps us improve the calculator and its explanations. This is CalculatorsPPM user feedback, not a Google review.
Hanna meters and most US hydroponic charts use the 500 scale: multiply EC by 0.5. If your meter is a Hanna (or reads "500"), this is your converter.
How to use this calculator
- Enter EC in µS/cm.
- Multiply by 0.5.
- Read PPM.
The formula
500-scale PPM = EC × 500/1000.
What the units mean
µS/cm — microsiemens per centimeter, the unit of electrical conductivity (EC) that meters actually measure before converting to a PPM estimate.
PPM (parts per million) — one part of solute per million parts of the total mixture. The workhorse unit for trace concentrations in water, air, and food.
Worked example
EC 1,400 µS/cm → 700 PPM (500 scale).
Quick reference
| EC | PPM (500) |
|---|---|
| 1,000 | 500 |
| 1,400 | 700 |
| 2,000 | 1,000 |
500 scale only.
Where you will actually use this
Using the wrong scale silently shifts every feeding decision by 40%.
- Hanna meter users
- US feeding charts
- Nutrient logging
Mistakes that give wrong answers
- Assuming all meters use 500
- Mixing scales between chart and meter
Key takeaways
- Formula: PPM = EC (µS/cm) × 0.5
- Remember: 500 scale only.
- Watch out for: Assuming all meters use 500
- Next step: run your own numbers in the calculator above, then verify with a measurement — calculated values are only as good as the inputs.
Frequently asked questions
What meters use the 500 scale?
Hanna and many US-market meters.
500 vs 700 scale difference?
700-scale PPM reads 40% higher for the same EC.