Enter Sample Data
Example Data Table
| Sample | Mode | Main Inputs | TDS Result | Quality Band |
|---|---|---|---|---|
| RO Outlet | Conductivity estimation | EC 42 µS/cm, 25°C, factor 0.65, dilution 1 | 27.30 mg/L | Very Low Mineral Content |
| Municipal Supply | Conductivity estimation | EC 480 µS/cm, 27°C, factor 0.67, dilution 1 | 309.80 mg/L | Elevated but Practical |
| Process Water | Gravimetric residue | Tare 45.000 g, final 45.145 g, volume 250 mL, dilution 1 | 580.00 mg/L | High Dissolved Solids |
Formula Used
1) Conductivity Estimation Method
Corrected EC at 25°C = Measured EC ÷ [1 + (Temperature Coefficient ÷ 100 × (Temperature - 25))]
TDS (mg/L) = Corrected EC × TDS Factor × Dilution Factor
This method is useful for fast field estimation when a conductivity meter is available and a suitable conversion factor is known.
2) Gravimetric Residue Method
Residue Mass (mg) = (Final Mass - Tare Mass) × 1000
TDS (mg/L) = Residue Mass × 1000 ÷ Sample Volume (mL) × Dilution Factor
This method measures actual dried solids after evaporation and is often used for laboratory confirmation.
Helpful Conversions
1 mg/L ≈ 1 ppm for dilute water samples.
g/L = mg/L ÷ 1000
% solution = mg/L ÷ 10000
How to Use This Calculator
- Enter a sample name so your exports are easy to identify.
- Choose Conductivity estimation for quick field results or Gravimetric residue for measured laboratory residue.
- Provide the sample volume and dilution factor. Use 1 if the sample was not diluted.
- For conductivity mode, enter conductivity, temperature, compensation coefficient, and a TDS factor that matches your water chemistry.
- For gravimetric mode, enter the tare mass and the final mass after evaporation and drying.
- Press Calculate TDS. The result appears above the form below the header.
- Use the export buttons to save the result as CSV or PDF for records, reports, or review.
Frequently Asked Questions
1) What does TDS mean?
TDS means total dissolved solids. It represents dissolved minerals, salts, ions, and very small organic matter present in a water sample.
2) Is mg/L the same as ppm?
For dilute water samples, mg/L and ppm are usually treated as nearly equal. This calculator shows both values for convenience.
3) When should I use conductivity estimation?
Use conductivity estimation when you need a quick screening result and have a conductivity meter. It is fast and practical for field work.
4) When should I use the gravimetric method?
Use the gravimetric method when you want a residue-based laboratory calculation. It is useful for confirmation and reporting after evaporation testing.
5) Why is temperature included?
Conductivity changes with temperature. Correcting readings toward 25°C improves consistency and makes estimated TDS more comparable between samples.
6) What is the TDS factor?
The TDS factor converts conductivity into an estimated TDS value. Common factors vary with water composition, so the best value depends on sample chemistry.
7) What does dilution factor do?
It adjusts the final result when the original sample was diluted before measurement or evaporation. A factor of 1 means no dilution occurred.
8) Can this calculator classify water quality?
Yes. It provides a practical quality band based on the calculated TDS level, helping you interpret whether the sample is low, moderate, or heavily mineralized.