Chemical Oxygen Demand (COD) Calculator
Calculate the Chemical Oxygen Demand of water samples using titration data. COD measures the amount of oxygen required to oxidize organic compounds in water.
Volume of water sample used in the test
Volume of titrant used for blank sample
Volume of titrant used for actual sample
Normality of ferrous ammonium sulfate (FAS) titrant
Default is 8 g/eq (O₂ has 4 eq/mol, 32 g/mol ÷ 4 = 8)
What is Chemical Oxygen Demand (COD)?
COD measures the amount of oxygen required to oxidize organic and inorganic matter in water. It is expressed in mg O₂ per liter (mg/L). COD is a key indicator of water quality and the degree of organic pollution in wastewater treatment.
How is COD calculated?
COD (mg/L) = [(V₁ - V₂) × N × 8000] / Vₛ, where V₁ = titrant volume for blank (mL), V₂ = titrant volume for sample (mL), N = normality of titrant, 8000 = 8 g/eq × 1000 mg/g × 1000 mL/L, Vₛ = sample volume (mL).
What is the difference between COD and BOD?
COD measures total oxidizable matter (organic + inorganic) using a strong chemical oxidant (dichromate). BOD (Biochemical Oxygen Demand) measures only biodegradable organic matter using microbial processes. COD is typically 1.2-1.5× higher than BOD.
What are typical COD levels?
Clean river water: 1-5 mg/L, moderately polluted: 10-50 mg/L, treated sewage effluent: 30-70 mg/L, raw sewage: 200-600 mg/L, industrial wastewater: 500-5000+ mg/L. Drinking water should have COD < 5 mg/L.