Conductivity to TDS Conversion

Posted by 28 Dec, 2010

The TDS to Conductivity correlation is non-linear and no single multiplier can determine the relationship. Therefore, a simple conversion table has been established to help you determine an approximate conversion factor.

Different types of salt have a different conductance value. The table below shows the three standard salts types. To simplify this conversion, Myron L has developed Conductivity/TDS meters that allow you to select the different salt types and does the conversion for you automatically. Take a look at the Ultrameter II 4P or the Techpro II TP1.

Conductivity at 25 °C TDS KCI TDS NaCI TDS 442
ppm Value Factor ppm Value Factor ppm Value Factor
84 µS 40.38 0.5048 38.04 0.4755 50.50 0.6563
447 µS 225.6 0.5047 215.5 0.4822 300.0 0.6712
1413 µS 744.7 0.5270 702.1 0.4969 1000 0.7078
1500 µS 757.1 0.5047 737.1 0.4914 1050 0.7000
8974 µS 5101 0.5685 4487 0.5000 7608 0.8478
12,880 µS 7447 0.5782 7230 0.5613 11,367 0.8825
15,000 µS 8759 0.5839 8532 0.5688 13,455 0.8970
80 ms 52,168 0.6521 48,384 0.6048 79,688 0.9961

TDS 442 – This solution best represents natural freshwater. The Myron L Company developed the 442 standard nearly 50 years ago. It is still the world’s most accepted standard.

TDS NACL – This sodium chloride solution best represents seawater, brackish water, or other high saline solution.

KCL TDS – This potassium chloride solution is a very stable salt and is an international calibration standard for conductivity measurements.

All of these different solution types are available here at an affordable price.

Categories : Application Advice, Technical Tips
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