Originally Posted by smyrnaquince
Is your kettle straight-sided? If so, you can do the math and just measure the depth of wort in the kettle to calculate its volume. Sanitize a metal ruler and dunk it right in the kettle, all the way to the bottom.
You really don't need to sanitize it. You will be boiling it anyway.
My ghetto rig currently I have been collecting first runnings in a 3 gallon kettle. After I heat up sparge water I collect everything in my larger kettle. I have used the HD bucket too. There is a lot of paranoia about those buckets but I have fermented in them and the beer turns out great. That's a personal decision tho.