Conductivity from Total Dissolved Solids
The inverse of the TDS estimate: EC (uS/cm at 25 C) = TDS (mg/L) / k, k commonly 0.55-0.75 (default 0.65).
Example
You enter
- Total dissolved solids (mg/L) 650
- TDS/EC factor (0.4-0.9, default 0.65) 0.65
You get
- Electrical conductivity 1000 uS/cm
Checked against published worked examples from: Eutech Instruments (Thermo Fisher).
Details, formula, and sources
Scope650 mg/L -> 1000 uS/cm, with an 867-1182 band from the k range so it is not read as exact. Predicts a conductivity-meter reading from a target/permit TDS or sets an EC alarm setpoint. An estimate, not a measurement; calibrate k to a lab result. The operator of record governs.
Formula or tableconductivity_us_cm = tds_mgl / k_factor; k commonly 0.55-0.75 (default 0.65); band EC = TDS/0.75 to TDS/0.55.
Source and editionElectrical conductivity from total dissolved solids (Standard Methods 2510), the inverse of the TDS estimate, by name.
Free accessThe TDS = k x EC correlation is a standard published water-quality relation; the k factor is calibrated to the specific water.
What governsEstimate. Operator of record and primacy agency govern.
API field namestds_mgl, k_factor, conductivity_us_cm
- Correlation EC (uS/cm at 25 C) = TDS (mg/L) / kStandard Methods 2510
- Factor range k commonly 0.55-0.75 by ion makeup; default 0.65water-quality practice
- Estimate not a measurement; calibrate k to a paired lab TDS and ECscope of this tile