Sometimes when you are pulling of your wort out of your mash tun, and get it all situated inside the kettle, you run into a problem: The original gravity is too low / too high for what I was attempting to target.
That can work, at times, but often there are specific recipe calculations that simply need to be hit spot on. BeerSmith, the home brewer’s most highly sought after brewing software, has some tips for correcting these missed numbers.
In their blog, they share tips on predicting your Original Gravity, what might cause you to miss your OG in the first place, and ideas to remedy the situation if you do miss (which is shared below).
If your gravity is too low, the calculation for the amount of dry extract to add is:
- Calculate the difference between your target and actual OG, then multiply by 1000. For example if you were targeting 1.056, but only hit 1.048 this would give us (1.056-1.048) x 1000 = 8 points
- Now we need to raise our gravity by 8 points which means we need to add 8 points/gallon of dry malt extract (DME) equivalent. Assuming a 5 gallon batch size, we need a total of 40 points of DME.
- DME has a potential of 1.046 which means it contributes 46 points/lb added, so we simply take the 40 points and divide it by 46 to get 0.9 lbs of DME to add.
If the gravity is too high, we can dilute it by adding water:
- This time we’ll assume our target was 1.056 but we overshot and came in with a gravity of 1.064, again using a 5 gallon batch. We’ll use the fact that the number of points times volume should be a constant to do the dilution.
- So we start by taking our starting points of 1.064 = 64 gravity points, and multiplying by our original volume of 5 gallons: 64×5 = 320 points
- Now we divide by our target points which is 1.056 = 56 points which will give us the target volume: 320 / 56 = 5.71 gallons
- Since we started with 5 gallons, we need to add 0.71 gallons of water to dilute our gravity to achieve the target of 1.056