The BYO recipe calculator aids brewers in formulating their beers. The calculator allows you to input the size of your batch of beer, your ingredients and some process variables (how long you boil the hops, for instance). From these, the calculator will estimate your original gravity (OG), final gravity (FG), bitterness (in IBUs), color (in SRM) and alcohol content (in ABV). There is also a section that lets you plan adjustments to your water chemistry. There are commercial software packages out there that are much more involved than this. However, the BYO recipe calculator has all you need to formulate recipes and get estimates of the statistics that matter most to homebrewers.

Process

The calculator’s default setting is for 5 gallons (19 L) of beer. If you are brewing a different volume, click on the “Process” part of the menu bar and enter your batch size. You can also enter your extract efficiency if you are an all-grain brewer.

Malt and Original Gravity (OG), SRM

Click on the “Malt” section of the menu bar, if it is not already highlighted. Next , go to the units menu (to the right) and select the appropriate units (either pounds or kilograms) from the pull down menu. Now, you can select the grains you want to add to your malt bill from the pull down menu. For each grain your select, you can type the amount to add to your recipe in the appropriate box. You may also type over the default values for extract potential and color, if your malt specs differ. If you wish to add a type of malt that is not found on this list, select “other” from the selections and fill in the extract potential and color. If you are an all-grain brewer, click on the “Process” section of the menu bar, type in your extract efficiency in the appropriate box and then click back to the “Malt” section. The default setting is 65%.

You can add up to 10 malts in any recipe.

Based on the amount of each grain and its extract potential, the calculator will give an estimate for the original gravity of your beer. Likewise, given the amount and color rating of each malt, it will calculate an estimated SRM.

Hops and IBUs

Click on the “Hops” section of the menu bar to bring up the hop section. Now you can select hops from the pull down menu to add to your recipe. For each hop variety you select, you must input the amount of time the hops are to be boiled (or, equivalently, the amount of time prior to the end of the boil that the hops will be added). You can also change the alpha acid rating from the default value, if needed, to reflect the rating of your hops.

Based the amount of hops, alpha acid rating, boil time and wort gravity, the calculator will give an estimated IBU value.

If you adding dry hops, enter zero for the boil time. Dry hops do not contribute bitterness to beer (just hop flavor and aroma). If you add hops as first-wort hops, hops added to a hopjack or added by some other method, you need to enter a boil time equivalent that yields the right utilization for these hops. Unfortunately, there are no estimates for these values that would apply in every situation. For FWH, try starting with the total boil time. For hops added to a hop jack, try a short boil time, perhaps 5 minutes. After brewing your beer, taste and see if you think those numbers should be adjusted.

Yeast and Attenuation, Final Gravity (FG) and alcohol content (ABV) Now click on the “Yeast” section. Here you will be able to choose the yeast strain for your beer. Once selected, you can change the attenuation if you wish. (You can also pick a final gravity (FG) the beer will reach by filling in the “forced FG” box.)

Based on the original gravity and the attenuation rate for the yeast strain, the calculator will give an estimated FG and alcohol content (by volume) of the beer.

If you add a substantial amount of simple sugars to the kettle or starchy adjuncts to the mash, you will want to increase the predicted attenuation of the yeast or lower the FG using the “forced FG” box. One way to do this is to enter the grain bill minus the sugar or adjunct. Select a yeast strain and see what the predicted FG is without the sugar. Then, add the sugar to the grain bill and input the previous FG in the “forced FG” box.

Water and color recommendations

There is also a section on water chemistry. This section does not affect the calculations for OG, FG, IBU, SRM or ABV. In this section, you can develop a plan for adding minerals and/or distilled water to your tap water to hit a certain water profile. To do this, you will need a copy of your water report. Enter the values for calcium, magnesium and carbonates in their appropriate boxes. Then, enter the total amount of water you intend to treat.

From there, you can input the amount of tap water and distilled water (in “parts”) that will compose the total volume. (For example, if you made 12 total gallons from 8 gallons of tap water and 4 gallons of distilled water, you could type in either 8 parts tap, 4 parts distilled or, equivalently, 3 parts tap to 1 part distilled.) If your water will be 100% tap water, type in 1 part tap, 0 part distilled.)

Now, you can add various mineral salts to your water. Just type the appropriate amounts into the appropriate boxes. The calculator will display the final values for each relevant brewing mineral. It will also give the optimal SRM for beer made from this kind of water. This is a rough estimate, to don’t worry about tweaking your water so it yields the exact predicted SRM; just look to see that you are in the right ballpark (with 10 SRM).

Statistics

The statistics section gives you the estimated original gravity (OG), final gravity (FG), International Bittering Units (IBU), color (in SRM) and alcohol content, by volume (ABV). If you entered a forced FG, the ABV for this is displayed separately. You can opt to print the recipe by clicking “print.”

Conclusion

The BYO calculator offers a quick way to do most homebrew recipe calculations. BYO also offers free spreadsheets for download that do essentially the same thing.

Have fun planning your brews.