Do i not know how to use a hydrometer?

So yesterday I made an attempt at an Irish ale. When I use brewing calculators, they all suggest that the OG should be around 1.071 to 1.068. What I got was 1.046 at 72 degrees, which corrects to 1.048. So did I do something wrong, am I not using the hydrometer correctly?

I was a stickler for keeping everything as exact as possible temp and time wise. Or is this just one of those things? Any suggestions would be appreciated.

Post the recipe.

two questions

1) full or partial boil
2) did you mix and aerate properly.

if you had to top off a partial you might have added too much.

aerating adds oxygen and bubbles to the wort. did you spin your hydrometer to keep the bubbles off. that would also effect the measurement

Extract? My guess is you didn't stir the top up water with your wort well enough, this is why you have a low gravity reading.

First assumption is that you're an extract brewer: extracts are notorious for giving you a low OG because it's really hard to mix up all the extract with top off water. With extract, I think it's just best to assume you hit expected OG if you topped off exactly to 5 gallons.

Extract brew or all grain?

One of the typical issues with extract brews is not adequately mixing the sample prior to taking a hydrometer reading.

7# breiss light DME
1# flaked barley
.5# breiss 80L crystal malt
.12# muntons chocolate malt
1/2oz UK Kent goldings (5)
1oz northern brewers (60)
1/2 tsp Irish moss (15)
Wyeast 084 Irish ale

That's an extract brew: me suspects it's just not adequate mixing of top off: no worries: assume target OG and then wait and see when the gravity stops.

Wow awesome replies! It was extract, and partial boil. Added wort to 2gals in the fermenter and then topped off to hit 5 gals. I stirred a bit more but that could def explain it.

extracts are notorious for giving you a low OG because it's really hard to mix up all the extract with top off water.

Click to expand...

I disagree. It's not hard to mix up. I think most people are not adequately finishing the procedure. After adding your top-off water you should aerate. I aerate by pouring back and forth from the boil kettle to my 6.5 gal. pail. I do this back and forth method at least 4 times. By the time you are finished the bucket will be full of foam and ready for the top and airlock. Take your reading at this time.
Or you can take a reading with with whatever volume you have after the boil is done and then convert it to whatever your final volume is going to be after you add the top-off water. You will get the same result. For instance, if the recipe says your SG should be 1.050 for 5 gal. That is 250 total gravity units (GU). The math is (50X5 gal=250 GU). If your volume after your boil is 3 gals. then your hydrometer should read 1.083 (250 GU/3 gal= 83). So its possible to take your reading before you add the top-off water as long as you understand the math.