Balancing your Beer with the Bitterness Ratio

by Brad Smith on September 26, 2009 · 16 comments

PiThe balance between bitter hops and sweet malts has always been important in crafting world class beer. This week we take a look at the bitterness ratio and how you can use it to improve the balance of homebrewed beer recipes.

The sweetness of malted barley and specialty grains must be offset by bitterness. Early beers used all kinds of herbs including ginger, caraway, cinnamon, citron, coriander, juniper, mint, myrtle, saffron, hysop, dill, thistles, and many others to counterbalance the sweetness of malt. Most modern beers use hops for bitterness, though some specialty beers like Belgian Wit still make use of other spices.

The idea of trying to quantify the bitterness to sweet malt balance is also not new. English brewers regularly used “pounds of hops per quarter of malt” for the last several hundred years to characterize the hops-malt balance. Modern brewers started using the modern equivalent, called the bitterness ratio or BU:GU ratio many years ago. The measure, determined by simply dividing the number of IBUs in a beer by the number of gravity units, provides a rough estimate of the balance between hop bitterness and malt sweetness. It is featured in Ray Daniel’s Designing Great Beers book where he lists the average bitterness ratio for many popular styles.

To calculate the bitterness ratio we start with the number of international bitterness units or IBUs. For example, lets say we start with a beer that has 30 IBUs. We then take the original gravity of the beer (for example 1.048), take the fractional portion (0.048) and multiply by 1000 to get the number of gravity points. In this example 1.048 would simply be 48 points. Now we take 30 IBUs and divide by 48 points to get a bitterness ration of 0.63. If you are using BeerSmith, the estimated bitterness ration (IBUs/OG points) is displayed just below the color on the recipe design page.

Obviously the bitterness ratio needed varies depending on the style of the beer. A hoppy India Pale Ale is going to have a much higher desired bitterness ratio than a barely hopped Weizenbier. To determine the correct target bitterness ratio, one needs to know the average IBUs and starting gravity for different beer styles. Fortunately the BJCP style guideline provides just such a resource. To calculate your target average style BU:GU ration, determine the average IBUs for the style guide and divide by the average OG points for the style. I’ve calculated the bitterness ratio for a few popular styles here from the 2008 guidelines:

  • American Amber: 0.619
  • Bohemian Pilsner: 0.800
  • Oktoberfest/Marzen: 0.449
  • Traditional Bock: 0.346
  • Blonde Ale: 0.467
  • California Common: 0.735
  • Ordinary Bitters: 0.833
  • American Pale Ale: 0.714
  • Brown Porter: 0.576
  • Dry Irish Stout: 0.872
  • English IPA: 0.800
  • Weizen/Weissbier: 0.240
  • Belgian Trippel: 0.375

The above is just a sampling, but gives us some idea of the range of average bitterness ratios for different styles. A higher bitterness ratio corresponds to more bitter beers overall. Not surprisingly many of the malty or high wheat German beers such as Weizen and Bock have low average bitterness ratios (0.240-0.345), while IPAs, Pale Ales, and those with high concentrations of dark malt such as stouts have much higher average ratios of 0.800 or higher. Many popular styles lie in the middle range of around 0.500, such as Oktoberfest, Porter, and Blonde Ale.

The bitterness ratio does not tell the whole story, however, as it does not take into account the individual grains making up the grain bill. For example Oktoberfest/Marzen has a malty flavor from its Munich malt grain bill base that is not reflected in its mid-range BU:GU ratio. Irish Stout, which requires a higher BU:GU ratio to balance its high concentration of black/stout roast malt has a relatively high 0.872 bitterness ratio, but the dry flavor of the roasted malt dominates the flavor profile more than hop bitterness.

Still, calculating the bitterness ratio for a given beer and comparing it to the average for your target beer style can help to create a beer with an appropriate flavor balance, especially when traditional ingredients are used. I personally like to do a sanity check on my bitterness ratio against the style guide to make sure I’m in the ballpark when creating a new recipe.

I hope you enjoyed this week’s article from the BeerSmith Home Brewing Blog. Please subscribe for regular weekly delivery, and don’t hesitate to leave a comment or send this article to a friend.

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{ 7 comments… read them below or add one }

steve witkowski November 13, 2010 at 1:23 pm

hello and thank you trying to write my first recipe extract brewing using % my question
how to figure each in the recipe in % to total up to 100 % example
70 % malt and than fill in the less with grains and adjuncts
looking for a couple of examples and or formulas and if i make a recipe with 12 lbs of malt
for anothe example thank you hope to hear from you

Brad Smith November 14, 2010 at 9:33 am

Typically percentages are quoted as raw weight – example 50% wheat would mean half of the total grain bill by weight is malted wheat. Here’s one way to handle this in BeerSmith. Lets say you have a recipe that is 60% pale malt, 20% crystal malt and 20% munich malt. You could enter it in BeerSmith as 6lbs pale, 2 lbs crystal and 2 lbs munich. Then use the “Adjust OG” tool to adjust the original gravity of the recipe to match your target – which will scale all of the ingredients proportionally to match your actual batch size and target gravity.

Brad

Glenn Roy April 17, 2011 at 3:27 am

Hi Brad,
I think your bitterness ratio guidelines for the styles of beer are way too high. I been using this method for hopping and anything above 0.66 (In my opinion) is undrinkable. Been there, done that.
Thank,
Glenn

Brad Smith April 17, 2011 at 7:22 pm

Glenn,
Thanks – but I actually calculated them by averaging the high/low bitterness to OG ratios from the BJCP guide. They really should not be excessively high particularly for hoppy styles like IPA.

Brad

Jason October 19, 2013 at 10:04 pm

I was hoping someone could explain the bitterness ratio to me. The main point I’m hung up on is why starting sugars from OG are considered. Shouldn’t the final gravity be the important number when it comes to sweetness? Does using OG try and account for unfermentables that would remain? If they remain wouldn’t FG still account for the sweetness? Or is this just customary?

Thanks for the great article!
Jason

Stu November 2, 2013 at 9:20 am

Jason – I agree. Its far from a perfect or exact system. The way I see it, theres no way you can compare a highly fermentable belgian golden strong where upto 20% of the grist is simple sugars with say a malty english ale grist with lots of residual sugar/body and derive anything useful. The thing that balances the bitterness in the glass is the residual body and sweetness (i.e. FG), not where it started from (OG).
However, I don’t think that is the way to use it. Rather than use it to compare styles, I use it as a reference point within a single style. So when fine tuning an IPA recipe, I can modify the perceived bitterness over successive batches by using the BU:OG ratio. It works within a single style because the grist composition is basically the same.

Just my 2c..

TommyK December 21, 2013 at 9:15 am

Hi guys, as far as i can see the reason for using gravity to assess your hop requirements is because of the hop utilisation during the boil. Don’t forget that if you boil hops in a high gravity wort you get less isomerisation, and less hop flavour for a given amount of hops.

What I find completely absent is a way to assess and measure the aroma additions which add tons of character to a beer but aren’t quantifiable in IBU’s because of the way the hop oils are used.

I guess that’s where experience and the ‘art’ of brewing comes in

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