One hitler shall henceforth be a unit of measurement equal to 6.0*106 human deaths.

Standard SI prefixes apply. Thus Harold Shipman's achievements amount to 36 microhitlers.

The true utility of the hitler as an SI unit is it allows useful unit conversions.

For example: the EPA currently values a human life as being worth 6.9 million us dollars (6.9 megadollars). A simple unit conversion thus gives us 1 hitler is equivalent to -41,400,000,000,000 dollars. (-41 teradollars).

It can therefore be quantitatively established whether or not someone is "worse than hitler". When congress failed to pass a stimulus bill in 2008 the market lost 1.2 trillion dollars in 1 day, roughly equivalent to 29 millihitlers. Joseph Stalin is the only human I know of who can be called worse than hitler, as his achievements clocked roughly 5 hitlers.

When your bank nails you with a 35 dollar fine, you can confidently tell the teller that they are currently fucking you over to the tune of 84 picohitlers and ask if they have a very tiny auschwitz behind the counter.

Double kill!