IBU by hop weight
IBU for 0.5 oz of 12% alpha hops at 60 minutes
0.5 oz of 12% alpha acid hops boiled for 60 minutes in 5 gallons at 1.050 gives 20.7 IBU by the Tinseth equation and 27.7 IBU by the Rager equation.
Rager reads 7 IBU higher here, about 1.34 times Tinseth. Neither is wrong: they are different published models, and a recipe is only consistent if you stay with one.
0.5 oz at 12% alpha, 60 minute boil, 5 gallons, 1.050 boil gravity
| Model | IBU | Basis |
|---|---|---|
| Tinseth | 20.7 | Standard |
| Rager | 27.7 | Standard |
| Difference | 7 | Standard |
| Alpha acid units (oz x alpha%) | 6.0 | Standard |
| BU:GU against 1.050 | 0.41 | Convention |
Rows marked Standard come from a published equation, constant or manufacturer specification. Rows marked Convention are widely repeated brewing practice with no governing document behind them. The difference matters, so this site labels it rather than blurring the two together.
Hops and hop handling gear
Prices are those returned when this page was last built and change often.
Cascade Pellet Hops (1 lb)
A pound of Cascade pellets, the classic American aroma hop, which is far cheaper per ounce than small packets.
Centennial Hop Pellets (8 oz)
Half pound of Centennial, a dual purpose American hop.
BSG Mosaic Hop Pellets (8 oz)
Half pound of Mosaic, a high impact aroma hop for dry hopping.
BSG Magnum Hop Pellets (8 oz)
High alpha bittering hop, which delivers a given IBU from a smaller weight of hops.
Citra Pellet Hops (1 oz)
Single ounce of Citra, the usual quantity for one late or dry hop addition.
YCH Citra Hop Pellets (1 lb)
A full pound of Citra for brewers dry hopping heavily and often.
TIZZE Hop Spider (300 micron)
Stainless mesh basket that keeps hop matter out of the wort, which makes transfer far cleaner.
TIZZE 4 x 10 inch Hop Spider
Four by ten inch 300 micron hop filter that hangs in the kettle.
Hop Hopper Spider Strainer Basket (6 x 14 inch)
Larger hop basket for heavily hopped ten gallon batches.
Digital Pocket Scale 200 g x 0.01 g
Hundredth of a gram resolution, which is the precision hop additions and water salts actually need.
BOMATA 1 kg x 0.01 g Digital Scale
Wider range 0.01 g scale, which covers both salt additions and whole hop packets.
Bonvoisin Digital Lab Scale 600 g x 0.01 g
Laboratory balance with a draft shield style body, for brewers building water profiles by the tenth of a gram.
Related on BrewGearCalc
- IBU calculator Tinseth and Rager, labelled
- Hop alpha acid chart
- Best hops to keep on hand
- IBU for 0.5 oz of 14% alpha hops at 60 minutes
- IBU for 0.5 oz of 10% alpha hops at 60 minutes
- IBU for 1 oz of 5% alpha hops at 60 minutes
- IBU for 0.5 oz of 8% alpha hops at 60 minutes
- IBU for 1.5 oz of 10% alpha hops at 60 minutes
- IBU for 1 oz of 10% alpha hops at 15 minutes
Frequently asked questions
- Should I use Tinseth or Rager for 0.5 oz of 12% hops?
- Tinseth is the more widely used of the two and most recipe software defaults to it, which is why 20.7 IBU is the number most brewers would quote here. Rager returns 27.7 IBU because it models hop utilisation differently. Pick one and use it for every recipe, because switching models mid-way makes your own recipes incomparable.
- Does boil gravity change the IBU from the same hops?
- Yes, and substantially. Both models reduce utilisation as boil gravity rises, because sugar in the wort suppresses isomerisation of the alpha acids. The same 0.5 oz of 12% hops produces measurably fewer IBU in a strong wort than in a weak one, which is why high gravity beers need proportionally more hops to taste equally bitter.
- Is calculated IBU the same as measured bitterness?
- No. Calculated IBU is a model of how much isomerised alpha acid should end up in the beer. Laboratory IBU is a measurement of what actually did. They often differ, particularly in heavily dry hopped beer, where perceived bitterness can rise without the measured figure moving much.
Researched from published brewing formulas, manufacturer specifications and verified owner reviews. This is general guidance, not professional advice.