Display omitted •Edible & non-edible vegetable oil, animal fat oil, waste oil and alcohol based biodiesels were analysed.•Twenty-four biodiesel fuel can be used in a diesel engine without much modification in operating parameter.•Diesel RK software was used and emissions parameters were studied.•Biodiesels showed less NOX, PM and smoke emission exhausted from five categories of biodiesel. In previous years, unconventional fuel studies have been conducted by many researchers through their experimental work and numerical simulation. Running down of fossil fuel raised crisis of full fill demand of energy consumption in the world. The attention of researchers to investigate renewable energy sources such as biodiesel are suggested, which are less destructive for environmental. The paper is aimed to mitigate emissions parameter like NOX, smoke, particulate matter (PM) and summary of emissions (SE) from five different categories such as, edible and non-edible vegetable oils, waste animal fats, waste oil and alcohol biodiesel. Two experimental validations were conducted on a single cylinder, direct injection diesel engine at constant advanced injection timing and speed with diesel, for a Diesel-RK model. Numerical analysis shows that most effected NOX pollutant emission for soybean (edible) by 21.79%, jojoba curcas (non-edible) by 23.0%, chicken fats (animal fats) by31.2%, grease oil (waste oil) by 15.8% and butanol (alcohol) by 94.56%. The PM emission are reduced by 45.59%, 84.97%, 93.78%, 23.83%, 48.18% for soybean, microalgae, poultry fats, frying oil and pentanol respectively and also reductions in smoke emission by 93.8%, 93.43%, 92.26%, 89.14% and 79.14% for sunflower, karanja oil, fish oil, frying oil and pentanol respectively. The most effected summary of emissions (SE) are reduced by 3.91%, 15.66%, 43.37%, 3.01% and 37.65% for soybean, jojoba curcas, veal oil, grease oil and pentanol respectively; at full load and engine speed, injection timing and compression ratio were remained unchanged.