actual and apparent attenuation

Hello everyone
Can somebody explain to me actual/apparent attenuation and the importance of the two?..I have a brew going now that started at an OG of 1.061..it is now 1.010 FG..i put my numbers through a attenuation calculator and it says my apparent attenuation is 83.33% and my actual is 67.83%..Im quessing the actual attenuation number is the accurate one..so why even have apparent?..just a little confusing

Off the top of my head...

Apparent attenuation is a calculation of the change in specific gravity only.

Actual attenuation calculates the change in specific gravity but also accounts for the fact that alcohol has been produced as a result of the decrease in sugar and that alcohol has a lower density than water.

Both are accurate. They just indicate slightly different things. And it is the apparent attenuation that is most often quoted by brewers.

Afterthought: Apparent attenuation is a straightforward/easy calculation and that is why it is used. You only have to know the OG and FG and it's easy math from there.

hey thanks alot ..still dont fully understand but thats why im gonna study the subject...So being my apparent attenuation is 83.33% its safe to say the brew is almost if not complete?..thanks cheers

That attenuation is high. But I would not use attenuation do definitively determine if a beer is done. Yes, I'm sure it's at least close to FG. But a stable FG over a couple of days is a better way to be sure.

Thanks again ..if sunday the fg is 1.010 i will bottle ..cheers