And while each person may vote differently, there is some very clear geographical patterning on how people will vote.
Researchers from the University of Bristol have found that at one extreme there are local authorities where support for leaving the EU is very low.
In fact, these local authorities are almost all in London, as well as most of Scotland.
Contrast that with England's east coast, as well as some older industrial areas - notably, Yorkshire and the West Midlands - and pockets on the south coast, where support for Brexit is far higher.
The researchers also found that the more people in an area who voted Ukip in 2014, the more who favour Brexit now. Even they say that result is "surely unsurprising".
More specifically, South Staffordshire has the highest proportion favouring departure from the EU, according to the age and qualifications profile of its population, followed by Havering, Gravesham, Boston, Kings Lynn, Mansfield, and Tendring (which includes Clacton).
The areas giving least support to Brexit are Lambeth, Hackney, Edinburgh, Haringey, Oxford, Cambridge, Bristol and Brighton – in general, places with fewer old people than the first group and many more graduates.
The results were found by using responses to YouGov polls, census data and results from the 2014 European Parliament election, as well as last summer's General Election.
Whether or not the estimates are correct will depend on factors such as turnout.