IBU Calculator - Tinseth-first
IBU is a lab-style estimate of bitterness from isomerized alpha acids. Enter your batch volume, boil volume, and target OG, then add hop additions with time, alpha acids, and weight.
The calculator estimates average boil gravity (or you can set it directly in Pro Mode) and computes IBUs per addition.
Use the results as a reliable starting point, then tune with the real-world multiplier to match your system and palate.
Inputs
Results
Per-addition breakdown
| # | Hop | AA% | Weight | Time | Form | Tinseth IBU | Rager IBU |
|---|---|---|---|---|---|---|---|
| Add hops to see a per-addition breakdown. | |||||||
How the math works
This calculator uses Tinseth as the primary bitterness model. For each hop addition it computes utilization, then converts that into IBUs using your final volume.
Tinseth utilization (used exactly): U = 1.65 × (0.000125^(SG−1)) × (1−exp(−0.04×time_min)) / 4.15
Tinseth IBU per addition (imperial form, used exactly): IBU = (W_oz × AA_percent × U × 74.62) / V_gal
Boil gravity handling: in Simple Mode, it estimates average boil SG from your OG and volumes by converting OG to points, scaling by final volume, then dividing by boil volume. This is a simplification because real gravity changes across the boil, but average gravity is a practical approximation.
Pellet vs whole: pellets get a utilization adjustment of +10% on U (per addition). Pro Mode can apply a final multiplier to tune predictions to your system: IBU_final = IBU_calc × (multiplier/100).
Disclaimer and practical reality check
IBUs are an estimate, not a promise. Perceived bitterness depends on more than IBUs: hop variety and age, boil vigor, wort pH, yeast behavior, sulfate-to-chloride balance, polyphenols, sweetness, and how fresh the beer is. Use this as a trustworthy starting point, then tune with experience.
Style-range reference (optional)
These are broad, practical ranges for quick orientation. Style guidelines vary and personal preference matters.
| Style family | Common IBU range | Notes |
|---|---|---|
| Blonde, Kölsch, mild lager | 10–25 | Soft bitterness, balance forward. |
| Pale ale, amber | 25–45 | Firm but not aggressive. |
| IPA | 40–70 | High bitterness, often supported by dry hop aroma. |
| Imperial IPA, barleywine | 60–100+ | Very high IBUs, perceived bitterness depends heavily on malt and alcohol. |
| Stout, porter | 25–60 | Roast adds bite, IBUs do not tell the whole story. |
| Sour or fruit-forward | 0–20 | Acidity and fruit can dominate perceived bitterness. |
Quick self-check examples (built-in tests)
Use the Load buttons and hit Calculate. The tool will also tell you if the Tinseth result lands in the expected range.
1.0 oz @ 60 min, 12% AA, pellet
1.0 oz @ 15 min, 6% AA, pellet
1.0 oz @ 5 min, 6% AA, pellet
Expected Tinseth: about 60–75 IBU
40 g @ 60 min, 10% AA, pellet
20 g @ 10 min, 6% AA, whole/leaf
Expected Tinseth: about 50–65 IBU
How to use this IBU calculator
If you are new to IBU math, start in Simple Mode. It is designed to get you to a solid, repeatable estimate fast, without the usual “wait, which volume did I just type?” mistakes.
If you are copying a kit sheet or clone recipe, match the units first, then put your attention on volumes and gravity. Those two choices heavily influence concentration and utilization.
Real volume beats “recipe volume” every time.
- Pick Metric or US. Metric uses liters and grams, US uses gallons and ounces. You can switch at any time. The calculator keeps the underlying values internally and only changes what you see and type, so switching units should not change the calculated bitterness.
- Enter final batch volume. This is the volume you actually end up with in the fermenter or packaged, not the size printed on the kettle. If you routinely leave a liter or two behind with trub and hop matter, use the smaller, real number. IBUs are normalized to final volume, so this directly changes the “bitterness per sip.”
- Enter boil volume. This matters most for partial boils. A smaller boil volume makes a denser wort during the boil, which reduces hop utilization in the Tinseth model. If you do full-volume boils, boil volume is often a bit higher than final volume because of boil-off and shrinkage. Use your typical kettle starting volume, not your end-of-boil volume.
- Enter target OG (planned original gravity). In Simple Mode the tool estimates average boil gravity from OG and your two volumes. It converts OG to points, scales by final volume, then divides by boil volume to get an average boil SG. Gravity does change during the boil, but average gravity is a practical approximation and keeps the calculator useful without turning it into a full simulation.
- Add hop additions, up to six. For each addition you actually boil, enter alpha acids, weight, and time. Hop name is optional, but it makes the breakdown table read like a real recipe sheet. Time is minutes in the boil, with 60 for a classic bittering charge. A time of 0 is treated as flameout and will show near-zero measured IBUs here. That is intentional, it is being honest about what this model can and cannot claim.
- Choose hop form. Pellets get a +10% utilization bump per addition, matching the assumption used by many common calculators. Whole or leaf hops use base utilization. If you are unsure, pellets are the safest pick for most modern hop products.
Read the results card. The big number is total Tinseth IBUs. The descriptor (low, moderate, high, very high) is a quick intensity label, and the gauge shows where you land on a 0 to 120+ scale. Then check the per-addition breakdown, it is the best troubleshooting tool in the interface.
If a 5-minute addition is doing heavy IBU work, something is off.
If your late or 0-minute additions are “carrying” the bitterness, it can be a sign the recipe assumes a process you are not actually doing, for example a long, hot whirlpool or hop stand that is not being modeled here.
When you want more control, switch to Pro Mode. You can optionally show a Rager comparison to match recipes that quote Rager IBUs, and you can set a utilization multiplier.
The multiplier is applied at the end of the calculation, so it is perfect for calibrating your system over time. I
f your beers reliably drink less bitter than predicted, nudge the multiplier up. If they drink sharper than predicted, nudge it down. Keep notes, make small changes, and it quickly starts to feel like your own brewhouse instrument.
Tip: calibrate with your own “known beers.” Brew a recipe you repeat, keep everything else steady, then adjust only the multiplier until the calculator matches how your beer actually drinks.
Hops, bitterness, and what IBUs really mean in brewing
Hops are the spice rack of beer, but they are also a structural ingredient.
They shape bitterness, aroma, flavor, foam stability, and even how the finish sits on your tongue.
Most brewers meet hops through alpha acids, because alpha acids are the main pathway to measured bitterness. I
n the boil, alpha acids isomerize into iso-alpha acids, which are more soluble and taste bitter. That is why a 60-minute addition is “bittering,” and why the same hop thrown in at flameout can smell enormous but often reads as mild bitterness on paper.
IBU is a lab number, your palate is the verdict!
IBU stands for International Bitterness Units. In practical terms, an IBU is one milligram per liter of iso-alpha acids, as measured by a standard laboratory method that extracts bitter compounds and reads absorbance at a specific wavelength. That is useful because it gives you a repeatable target for recipe design, but it is not the same thing as what your tongue experiences. If you want the deeper backstory on why IBUs can get slippery as hop loads climb, read The mystery of International Bitterness Units. It walks through the gap between the tidy lab number and the messy reality of perception.
The chemistry matters. Alpha acids (humulone family) are the headline, but hops also carry beta acids, polyphenols, and essential oils. Essential oils are why hops can smell like grapefruit, passionfruit, pine, resin, or crushed herbs.
They include compounds like myrcene, humulene, caryophyllene, and linalool, and the balance depends on variety, growing conditions, and handling. In the boil, some oils flash off, others transform, and some survive into the finished beer. That is why the same hop can present differently depending on when you add it. For a hop-aroma deep dive, see Lupulin Labyrinth: How hops shape beers.
Bitterness is not one sensation.
A beer can be high IBU but feel smooth if it has enough malt sweetness, a higher finishing gravity, or softer water chemistry. Another beer can be moderate IBU but feel biting if it is very dry, highly carbonated, and built on sulfate-forward water. Sulfate tends to sharpen bitterness perception, while chloride can round it into a fuller, softer finish.
Temperature plays a part too, cold beer often reads less bitter than the same beer as it warms, and aroma strongly primes your brain for what it expects to taste.
So how do you use IBUs well?
First, treat IBU as a recipe design dial, not a final verdict. If you want a crisp pilsner that snaps but does not scrape, you might aim for 25 to 35 IBUs, then let malt type, yeast, and water do the rest. If you want an American pale ale, 30 to 45 can land you in a bright, drinkable zone. If you are building an IPA, 45 to 70 is common, but drinkability depends on balance. At the extreme end, “100+ IBU” is often more marketing than sensory reality, because solubility limits and hop material effects make the number less predictive.
The important question becomes: how does it drink.
Second, understand utilization.
Utilization is the fraction of alpha acids that end up as bitter iso-alpha acids in solution. It rises with time, but the curve flattens. The jump from 10 to 30 minutes is much bigger than the jump from 60 to 90.
Utilization also drops in higher gravity wort. That is why partial boils often undershoot bitterness unless you compensate, the wort is denser in the kettle, so fewer iso-alpha acids dissolve. Pellet hops generally give a bit more utilization than whole hops because they break up and expose resin more readily during the boil, which is why many calculators apply a small pellet bonus.
Third, separate bitterness from hop flavor and aroma on purpose. Late additions, whirlpool additions, and dry hopping are mostly about oils and polyphenols. A 5-minute addition can add some measured bitterness, but it is often a small portion of the total. Whirlpool additions can add bitterness depending on temperature and contact time, but most simple IBU models do not try to guess it because everyone’s whirlpool schedule is different.
Dry hopping contributes no measurable IBUs in standard models, yet it can increase perceived “bite” through polyphenols and hop-derived compounds that are not captured in the IBU test. This is one reason heavily dry hopped beers can feel sharper than their IBUs suggest.
How do you assess IBUs and bitterness at home?
Start by calibrating your palate against known beers. Pick two or three commercial examples you like, note their published IBU ranges, and taste them side-by-side with your own beer.
Then ask practical questions: does the bitterness arrive early or late.
Is it smooth or scratchy. Does it linger. Does it feel herbal, citrusy, resinous, or just blunt. Your notes matter as much as the number. Over a few batches you can tune your system. That is why this calculator includes a utilization multiplier, it lets you bring prediction and experience into alignment without rewriting the underlying chemistry.
Finally, remember that IBU is only one dimension of hop design. Modern hop-forward brewing is about layering.
A clean bittering charge sets the frame, then mid-boil additions build flavor, then late and cold-side hops paint the aroma. If you want a broader hop reference hub, with varieties, techniques, and hop-focused brewing guidance, keep this hops page bookmarked. Treat IBUs as your bitterness compass, then let hop choice, timing, water, and yeast turn that compass into a beer with character.
Chase balance, not bragging rights.
One last sanity check: if a beer tastes harsh at the same IBU target, look at dryness (final gravity), water sulfate, and hop matter carryover first. If a beer tastes flabby at the same IBU target, look at sweetness, chloride-heavy water, low carbonation, or old hops.
The goal is not to chase a number, it is to build the kind of balance you actually want to drink.