Free Nitrous Oxide Emissions calculator with clear step-by-step results.
Nitrous oxide from managed soils is estimated from the nitrogen applied, not from the fertiliser mass. The IPCC default is that 1% of applied nitrogen is emitted as N₂O-nitrogen, and that figure must then be converted from nitrogen mass to N₂O mass by the molar ratio 44/28 — a step that is easy to miss and understates the answer by 57% if skipped. Indirect emissions from leaching, runoff and volatilised ammonia are added on top, then GWP converts the total to CO₂ equivalent.
Nitrogen emitted as N₂O-N
Direct N₂O-N = nitrogen applied × EF1; indirect = direct × indirect share
Convert and weight
N₂O = N₂O-N × 44 ÷ 28; CO₂e = N₂O × GWP100
Emission factors, indirect fractions and GWP values are prescribed by IPCC guidelines and national inventory methodologies, and vary with soil, climate and management. Use official country-specific factors for any regulatory or certified reporting.
The emission factor is expressed as kilograms of nitrogen emitted in the form of N₂O. One N₂O molecule has a molar mass of 44 but contains 28 of nitrogen, so converting from N₂O-N to N₂O means multiplying by 44 ÷ 28 = 1.571.
265 in IPCC AR5 and 273 in AR6, with 298 in the older AR4. Nitrous oxide has an atmospheric lifetime of over a century, so unlike methane its 20- and 100-year values are close.
Nitrogen that leaches into water or volatilises as ammonia is still nitrified and denitrified downstream, producing N₂O away from the field. IPCC defaults put this at roughly a quarter to a third of the direct amount.