Scientists have devised an online "impact effects calculator" which they claim can work out what would happen if an asteroid hit the Earth.

An international team from Purdue University in US and Imperial College London has created the online 'Impact Earth!' calculator where users can type in size of their hypothetical asteroid, its speed, what it will hit, its angle of entry and even how far they are from the blast.

And, for those who cannot visualise how big their asteroid should be, there is even a helpful drop-down menu of pre-set sizes which include "school bus", "humpback whale", "Empire State Building," the 'Daily Mail' reported.

The website's algorithms then calculate what the effects of the asteroid's impact would be on the Earth's axis, whether there would be a fireball and what chance of surviving any bystanders would have.

It can even tell one you how far one should be from the impact to avoid being buried in the material thrown up from any crater that is left behind.

Imperial's Dr Gareth Collins was quoted by the British newspaper as telling the 'BBC':"One of the major new additions is the estimates for tsunami wave height at a given distance away from an ocean impact.

"This had been a popular request, but we didn't put it in the original calculator because there simply wasn't consensus back then on what the hazard was. There's since been some good research and we now have a better understanding of the issue."

He added: "The site is intended for a broad global audience because an impact is an inevitable aspect of life on this planet and literally everyone on Earth should be interested."