The Handbook Emission Factors for Road Transport (HBEFA) is a Microsoft Access database application providing emission factors, i.e. the specific emissions in g/km, for all current road vehicle categories (passenger cars, light duty vehicles, heavy duty vehicles, buses, and motorcycles). Emission factors are provided for all regulated and the most important non-regulated air pollutants as well as for fuel consumption and CO2. HBEFA is used to estimate road transport emissions on different spatial aggregation levels from national to street level.