EC to PPM converter for hydroponics and indoor growing

This EC to PPM converter helps hydroponic growers, indoor gardeners, and greenhouse growers convert electrical conductivity readings into PPM values and convert PPM back into EC. It is useful when comparing nutrient charts, checking reservoir strength, calibrating feeding routines, and avoiding overfeeding or underfeeding in hydroponic systems.

Because different meters use different conversion scales, this tool supports the most common standards: 500 scale, 640 scale, and 700 scale.

How to convert EC to PPM

The formula is:

Examples:

This is why two growers can measure the same nutrient strength but see different PPM readings if their meters use different scales.

How to convert PPM to EC

The reverse formula is:

Example:

This is useful when a nutrient chart gives a PPM target but your EC meter displays only conductivity values.

What each parameter means

• EC: electrical conductivity of your nutrient solution.
• PPM: parts per million, a converted concentration value shown by many TDS meters.
• 500 scale: common conversion scale used by some TDS meters.
• 640 scale: another common conversion standard.
• 700 scale: also widely used in hydroponics and nutrient charts.
• Value: the EC or PPM reading you want to convert.

Why EC and PPM readings can differ

A grower can have the same nutrient solution but see different PPM numbers depending on the meter scale. That does not always mean the nutrient strength changed. It often means the reading was converted using a different factor.

For best accuracy, always use the same scale across your meter, nutrient chart, feeding log, and grow routine.

Best practice for growers

1. Check which scale your meter uses.
2. Compare nutrient charts using the same scale.
3. Use EC when possible because it is the more direct measurement.
4. Track your reservoir readings consistently.
5. Combine EC checks with pH monitoring for better nutrient management.