Map Scale Bar Grossly Incorrect [duplicate]

Question

I am working with open data from the City of Toronto. I am using a base layer of property boundaries which can be found here:

http://www1.toronto.ca/wps/portal/contentonly?vgnextoid=c3a11a23871b9310VgnVCM1000003dd60f89RCRD&vgnextchannel=1a66e03bb8d1e310VgnVCM10000071d60f89RCRD

The default projection system I am using is WGS84. However, when I place the map, at any scale, in print composer the scale bar is completely wrong. I would like to find a way to measure distance from lot lines accurately, but need an accurate scale. I have tried changing the CRS settings without luck.

Also, is there a way in QGIS like there is in Autocad where if I know the distance between two points and input that, the scale of the shapefile will adjust to my measurement accordingly?

I am using QGIS 2.2 btw.

Answer 1

This answer is from an Esri help page, not QGIS, but the principle still holds true:

A scale bar on a map that is set to a Geographic Coordinate System, using units of decimal degrees, only measures distances correctly at the Equator.

To apply a scale bar that measures distances correctly over all areas of the earth's surface, the [map] must be set to a Projected Coordinate System.

Transform the data to a new projection to measure distances or to have a useful scalebar.