Chemistry

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TDS Calculator.

Estimate total dissolved solids from conductivity and an explicit calibration factor.

On-device calculationNo signup
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Set your values

Results update as you type.

How to Use

TDS = conductivity × the user-supplied calibration factor. The factor is solution- and instrument-dependent.

Use a named source convention for coefficients and units. This page does not provide laboratory, medical, species, or food-safety advice.

Use Cases

Water Quality Monitoring

Quickly estimate TDS levels in drinking water, aquariums, or hydroponics to ensure they are within acceptable ranges.

Example: Measure conductivity of aquarium water as 500 µS/cm, use factor 0.5 to get TDS of 250 ppm.

Educational Experiments

Use in chemistry labs to demonstrate the relationship between conductivity and dissolved solids in various solutions.

Example: Compare TDS of tap water and saltwater using different calibration factors.

Frequently Asked Questions

How does the TDS calculator estimate total dissolved solids?
The TDS calculator estimates total dissolved solids by multiplying the conductivity value (in µS/cm or mS/cm) by a calibration factor you provide. This factor accounts for the relationship between conductivity and TDS, which varies with water composition.
What is a typical calibration factor for TDS conversion?
A common calibration factor is 0.5 to 0.7 for many natural waters, but it can vary. For example, a factor of 0.64 is often used for general purposes. The calculator lets you input your own factor to match your specific water sample.
Can I use this calculator for any type of water?
Yes, you can use it for various water types, but the accuracy depends on the calibration factor you choose. Different water sources (e.g., freshwater, seawater, wastewater) have different ionic compositions, so using the correct factor is essential for accurate TDS estimation.

Tips & Common Mistakes

Tips

  • Always calibrate your conductivity meter with a known standard solution to ensure accurate readings.
  • Choose a calibration factor based on the typical composition of your water sample; consult local water quality data if available.
  • Ensure conductivity and TDS units are consistent (e.g., µS/cm and ppm) before entering values.
  • For precise results, measure the water temperature and adjust conductivity readings to a standard temperature (usually 25°C).

Common Mistakes to Avoid

  • Using a generic calibration factor without considering the specific water source, leading to inaccurate TDS estimates.
  • Forgetting to convert units (e.g., using mS/cm instead of µS/cm) without adjusting the factor accordingly.
  • Ignoring temperature effects on conductivity, which can cause significant errors if not corrected.

Last updated: August 13, 2026