how many kilometers are from london to halifax?

Answer 1

You must be more specific if you want an accurate answer. You don't specify which London and which Halifax you're asking about. Canada, United Kingdom or USA?
I suppose your question refers to Canadian cities. In that case, the distance between London, ON and Halifax, NS is about 2020 km.
If this is not what you wanted, use the second link and make the appropriate choices.

Answer 2

Approx. 1,425 KM (London, Middlesex County, Ontario, Canada - Halifax, Nova Scotia, Canada)

Approx- 250-301 KM (London, Anglia (England), United Kingdom of Great Britain and Northern Ireland- Halifax, Calderdale Borough, West Yorkshire, Anglia, United Kingdom of Great Britain and Northern Ireland)

Approx- 4,602- 4,660 KM(London, Anglia, United Kingdom of Great Britain and Northern Ireland - Halifax, Nova Scotia, Canada)

Approx- 5,675 KM(London, Middlesex County, Ontario, Canada- Halifax, Calderdale Borough, West Yorkshire, Anglia, United Kingdom of Great Britain and Northern Ireland)

*To narrow down the range, get the average of the distance range. (ex. (4602 + 4660) /2= 4631 KM) then compare the output result of the calculations of the site (http://www.geobytes.com/CityDistanceTool.htm). Put in the distance difference of the 2 outputs and get the average again which might considerably be an accurate measurement of inter-urban distance.