Chemistry

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Chemical Oxygen Demand Calculator.

Calculate COD from blank and sample titrant volumes with an explicitly entered equivalent conversion factor.

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Results update as you type.

How to Use

COD = (A − B) × N × F ÷ V, where A is blank titrant, B is sample titrant, and F is your entered reporting factor.

Every material coefficient and convention is an input. No element, fluid, lab-method, or safety database is queried; results update after a short debounce.

Use Cases

Wastewater Treatment Monitoring

Determine the organic pollution load in influent and effluent to assess treatment efficiency and compliance.

Example: Measure COD of raw sewage and treated effluent to verify reduction.

Industrial Effluent Analysis

Evaluate the strength of industrial discharges before release or pre-treatment.

Example: Check COD of textile plant wastewater to meet discharge limits.

Frequently Asked Questions

How do I calculate COD using this calculator?
Enter the blank titrant volume, sample titrant volume, and the equivalent conversion factor (mg O2 per mL titrant). The calculator subtracts the sample volume from the blank, multiplies by the factor, and gives the COD in mg/L.
What is the equivalent conversion factor in COD?
It's a factor that converts the volume of titrant used (usually ferrous ammonium sulfate) to the equivalent oxygen mass. It depends on the normality of the titrant and the sample volume. You must enter it explicitly.
Why do I need both blank and sample titrant volumes?
The blank titration accounts for any oxidizable impurities in the reagents. Subtracting the sample volume from the blank volume corrects for these, ensuring the COD value reflects only the organic matter in your sample.

Tips & Common Mistakes

Tips

  • Ensure your blank and sample titrant volumes are in the same units (usually mL) for accurate subtraction.
  • Use a freshly prepared blank to account for reagent impurities and get reliable results.
  • Double-check the equivalent conversion factor: it must match your titrant normality and sample volume.
  • Run samples in duplicate to confirm reproducibility and avoid random errors.

Common Mistakes to Avoid

  • Forgetting to subtract the sample volume from the blank volume, leading to overestimation.
  • Using an incorrect or outdated conversion factor, causing systematic errors.
  • Mixing up units (e.g., mL vs L) when entering volumes or interpreting results.

Last updated: August 13, 2026