How often to check SG?

New brewer here and I have been reading a lot on here about checking SG. Most say to check it often.
Is this every 3-5 days or more or less?

I feel like anymore would be bad for fermentation because you are exposing your batch to oxygen each time. Is this small exposure time worth worrying about?

Just check prior to fermentation (to get your OG) and then when fermentation has completed (to get your FG). Anything else is a waste of time, waste of beer, risks baddies getting into the beer, and is completely unnecessary.

The more you check your gravity, the bigger chances you have to infect it. I normally take a gravity reading when I transfer to the secondary. Let it there for 1.5 or 2 weeks than take another one and another one 2-3 days after to see if it didn't change. If it didn't, it's time to bottle/keg.

Checking your gravity everyday won't make a better beer...

That is what I was thinking. I must have misread something. How will you know is it is indeed done fermenting without checking for FG twice and recording no change?

Edit: Answered my question, thanks guys!

I must be doing it wrong because I check before it goes into the fermenter (unless I forget) and when I am pretty sure it is done as a final check that things didn't go awry. It would be better for a new brewer to check more than once when they think the beer is done. I'd suggest you check it after 2 weeks and then again about 3 days later. If there is no change it is done fermenting. You can bottle it then or you can wait and let it have more time to mature. I usually leave mine in the fermenter for at least 3 weeks and if I am busy then it can wait for me to get un-busy. The longest I waited was 9 weeks and that beer was very good after only a couple weeks in the bottle while others bottled sooner took 3-4 weeks to mature.

Make sure you sanitize whatever you draw a sample with (wine thief or turkey baster work) and discard or drink the sample when done so you don't chance contaminating the batch when you are so close to having good beer.

RM-MN got it right, some of the other responses I would consider as bad advice. It is true that you should not check constantly during fermentation but you need to take a gravity reading before fermentation to get your original gravity, then you should check it once a few days before you plan to bottle, and then once again at least a day or two later. This is the only way that you can know whether your beer is done fermenting with any certainty. For a typical beer I make, I will take my OG reading prior to pitching yeast, then take another reading at about 3 weeks, and then another 3 days later. If there is no change in the gravity reading for those two readings, it is safe to bottle. If there is any change then you know that fermentation is still active and you need to wait longer.

Check it before it gets pitched and then after it seems fermentation is done check it again. If there is any doubt about whether fermentation is done check it again three days later to see if the numbers changed. If no change then that is your final reading. If there is change then fermentation was not done before so you need to wait and check again.

I normally measure the Specific Gravity of a brew three times:
First time after sparge completes for pre-boil gravity and to check efficiency
Second time after chilling for Original Gravity
Third time on day 28 of fermentation to record final gravity.

No reason to do more ... usually after 28 days I am fairly positive the fermentation is complete specially since I am usually 2 points under expected final gravity based on yeast profile for attenuation.

BlackGoat said:

RM-MN got it right, some of the other responses I would consider as bad advice. ....

Click to expand...

seriously? Everybody's basically saying the same thing! The only distinction is that you're saying to check the FG twice. Sure, it makes sense to check the FG twice if you're not paying much attention to know it has stopped, or if you're in a huge rush. Personally, if I'm not sure it's done, I'd rather just give it a couple days instead of wasting time, beer, and risk by taking repeated gravity readings.

I just meant when you say that its unnecessary and a waste of time... I'm sure that people who have had bottle bombs because they bottled before fermentation was complete would take think that this is entirely necessary. For new people starting out, how would they know that fermentation is complete? Airlock activity can't be trusted.

Ok, gotcha, we're agreed. If you can't determine if your fermentation has ended (due to lousy equipment) and you bottle, then yes you may want to do two FG readings to be sure. In my dozens and dozens of batches, airlocks have been 100.00% accurate, since I use carboys and orange caps. So I've never once had a reason to do two FG readings.

The OP can take whatever advice he likes, here are some similar threads on here so you can get an idea of other people's opinions on this...

https://www.homebrewtalk.com/f39/my-beer-done-fermenting-72506/

https://www.homebrewtalk.com/f39/my-brew-ready-bottle-300472/

https://www.homebrewtalk.com/f163/my-beer-ready-bottle-169725/

https://www.homebrewtalk.com/f39/newbie-ready-bottle-cloudy-83481/

https://www.homebrewtalk.com/f39/how-do-you-know-your-beers-done-fermenting-397603/

https://www.homebrewtalk.com/f39/how-check-fermentation-has-finished-without-hydrometer-300792/

https://www.homebrewtalk.com/f39/hydrometer-readings-250208/

Good luck!