Calculating OG

When calculating the OG of my wort using my hydrometer, how can I adjust for the affects of air? and are there other factors that could be affecting my OG reading that I should account for as well?

affects of air?

Just put the hydrometer in the sample, spin, and take a reading. Adjust as necessary for the sample temperature.

Temperature.

what effects of air?

You should correct the reading for the temp. Most are calibrated to either 60F or 68F

ok, thank you very much

If partial boil extract brewing, know that it is difficult to completely mix the boiled wort with the top-off water, which will give you a false reading on the hydrometer.

It is safe to assume the calculated OG is more accurate than the measured OG if you followed the recipe directions correctly (right amount of extract and batch size).

Once it starts fermenting, it will all mix together, then you can trust your hydrometer readings.

Is the reading usually off by a considerable amount or is there a better way to measure it? I was hoping to make a few brews without recipes and be able to accurately calculate my OG before fermentation.

beersmith my friend