Chrome Version       : 52.0.2743.116 (Official Build) m (32-bit)
URLs (if applicable) : http://stackoverflow.com/questions/38823353/chrome-canvas-2d-context-measuretext-giving-me-weird-results
Other browsers tested:
  Add OK or FAIL, along with the version, after other browsers where you
have tested this issue:
     Safari:
    Firefox: OK 48.0
         IE:

What steps will reproduce the problem?

Run the below javascript code.

let canvas = document.createElement('canvas')
let ctx = canvas.getContext('2d')
ctx.font = '11pt Calibri'
ctx.fillStyle = '#000000'

console.log(ctx.font)
console.log(ctx.measureText('M').width)
let temp = ctx.font
ctx.font = temp
console.log(ctx.font)
console.log(ctx.measureText('M').width)

What is the expected result?

Expected results are.

11pt Calibri
12.53........// (accuracy varies)
11pt Calibri
12.53........// (accuracy varies)
Both numbers must match

What happens instead?

15px Calibri // (11pt transformed to 15px on the fly, which is incorrect)
12.53....... // (accuracy varies, number is slightly larger than correct)
15px Calibri // (11pt transformed to 15px on the fly, which is incorrect)
12.82....... // (number is a massive 0.3 off the previous number, yet they should be the same)