Specific Gravity Question

Hey guys just started with home brewing and got my first batch going today! It was the Irish Red from midwest.

I messed up when trying to ready the specific gravity however I took a sample from the boiling pot before I added the top up water. I got 1.132 at 80 degrees. I figured since I had 2 gallons in the boiling pot and topped up to 5 gallons could I just average the gravity out...

For example find the specific gravity of tap water, then take that and multiply by 3/5s. Then take the 1.132 I got and multiply it by 2/5s. If I add the two together will it be an accurate measurement?

The SG of water should be 1.000. That's kind of the point of the scale. Higher or lower gravity than water. Your tap water could be a LITTLE different since 1.000 is distilled water, but not that much.

Why not just take the SG now? Nothing wrong with that.

I doubt it will be an accurate measurement. By the way, congrats on your first batch! I go along with cat; take a reading after it is topped to your final fermentation volume, adjust the temp (if needed) and calculate the starting gravity.

You're supposed to take the reading before you pitch your yeast, but it's not going to mess it up doing it after, if that's what you're worried about.

To calculate it you have 2g with 1.132 SG. 2 x 132 = # of points of gravity total.
It is now in 5g so (2x 132)/5 = 52.8. Your calculated SG is 1.053. But like Cat says, you can measure it now which will be more accurate.

GT

If you take the gravity after adding top up water, remember to mix really well before taking the sample. Personally, I would do the calculation like Got Trub said, rather than wasting another sample.

-a.