Beer IBU Calculator — Tinseth Formula
Beer IBU calculator using the Tinseth formula: enter hop grams, alpha acids, boil time, volume and gravity to get bitterness in IBU. Free homebrew tool.
- Data verified · July 2026
- Edited by Martín Rodríguez
- Formula verified by automated tests
- Private — runs on your device
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How to use this calculator
Follow this tool’s steps, then review its formula, assumptions, and limits below.
When to use this calculator
- You're designing an IPA recipe and need to dial in the bitterness target.
- You switched hop varieties and need to adjust grams to match the original IBU.
- You want to clone a commercial beer and match its IBU profile.
- You're testing different boil times and want to see the bitterness impact.
- You're making multiple hop additions and need the total IBU across all of them.
IBU Ranges by Beer Style (BJCP 2021 Guidelines)
| Beer Style | IBU Range | Character |
|---|---|---|
| American Light Lager | 8–12 | Very low bitterness |
| Hefeweizen | 10–15 | Low bitterness |
| Stout | 25–50 | Medium bitterness |
| Pilsner | 25–45 | Medium bitterness |
| Pale Ale | 30–50 | Medium-high bitterness |
| IPA | 40–70 | High bitterness |
| Imperial Stout | 50–90 | High bitterness |
| Double IPA | 60–100 | Very high bitterness |
Source: Beer Judge Certification Program (BJCP) — 2021 Style Guidelines (bjcp.org/style/2021/)
How it works
What Are IBUs?
IBUs (International Bitterness Units) measure milligrams of iso-alpha acids per liter of beer. During the boil, the hop alpha acids (mainly humulone, cohumulone and adhumulone) isomerize under heat and dissolve into the wort, adding bitterness to the finished beer. The human-perceptible range is roughly 5–120 IBU; above ~100, most people can't tell additional differences apart.
The Tinseth Formula
Glenn Tinseth's formula (published in Brewing Techniques, 1995) is the most widely used standard in homebrewing:
IBU = Utilization × (AA% × grams × 1000) / (Volume_L × 100)
Utilization = Gravity_factor × Time_factor / 4.15
Gravity_factor = 1.65 × 0.000125^(OG − 1)
Time_factor = 1 − e^(−0.04 × minutes)Why divide by 4.15: this divisor normalizes the curve so that utilization at 60 min in water (OG 1.000) comes out to ~26.9%, consistent with Tinseth's empirical measurements.
Why gravity reduces utilization: in high-gravity worts there is less free water and the iso-alpha acids are less soluble; a wort at OG 1.080 can lower utilization by 15–20% relative to OG 1.050 at the same boil time.
How It Is Calculated: Step by Step
1. Identify each hop addition: AA%, grams, time in the boil and the wort volume at that moment.
2. Calculate the gravity factor using the boil OG (not the final diluted OG).
3. Calculate the time factor using the boil minutes of that addition.
4. Get the utilization by dividing the product by 4.15.
5. Calculate the IBUs of that addition and add up all additions.
> Quick example: 28 g of hops at 10% AA, 60 min, OG 1.055, 20 L.
> Gravity_factor = 1.65 × 0.000125^0.055 ≈ 0.874
> Time_factor = 1 − e^(−0.04×60) ≈ 0.909
> Utilization = (0.874 × 0.909) / 4.15 ≈ 0.191 (19.1%)
> IBU = 0.191 × (10 × 28 × 1000) / (20 × 100) ≈ 26.7 IBU
IBU by Style (BJCP 2021)
| Style | Typical IBU |
|---|---|
| American Light Lager | 8–12 |
| Hefeweizen | 10–15 |
| Pilsner (Bohemian) | 30–45 |
| Pale Ale | 30–50 |
| American IPA | 40–70 |
| Double IPA | 60–100 |
| Stout | 25–50 |
| Imperial Stout | 50–90 |
Utilization by Boil Time (OG 1.050)
| Minutes | Approx. utilization |
|---|---|
| 5 | 5% |
| 15 | 12% |
| 30 | 18% |
| 60 | 24% |
| 90 | 27% |
The curve is asymptotic: going from 60 to 90 min adds barely 3 percentage points; boiling beyond 90 min gives marginal returns and can increase astringency.
Addition Types and Their Real Impact
BU:GU Ratio (Bitterness-to-Gravity)
Divide the IBU by the Gravity Units (the last two digits of the OG; e.g., OG 1.052 → GU = 52):
| BU:GU | Perception |
|---|---|
| < 0.5 | Malt-forward, sweet |
| 0.5–0.8 | Balanced |
| 0.8–1.2 | Distinctly bitter |
| > 1.2 | Very bitter (DIPA, Imperial IPA) |
What This Formula Does NOT Include
Common Mistakes
1. Using the final OG instead of the boil OG. If you do a concentrated boil and then dilute, use the volume and gravity during the boil, not the final volume.
2. Forgetting to update the AA percentage. AA declines in storage: poorly kept hops can lose 20–40% of their potential in a year at room temperature.
3. Counting dry hop as bittering. It adds no isomerized IBU; including it inflates the calculation.
4. Ignoring the whirlpool volume. If you add hops at the end at high temperature (>80 °C), real isomerization occurs; standard Tinseth underestimates it and there are empirical whirlpool corrections.
See also: hop utilization by boil time.
Example: American Pale Ale
Frequently asked questions
Why use the Tinseth formula over other IBU calculations?
Do IBUs decrease as beer ages?
Does dry hopping add IBUs?
What is cohumulone and why does it matter?
Do hop pellets give more IBU than whole hops?
At what temperature do alpha acids isomerize?
How do I adjust a recipe if my IBU is too high or too low?
What's a good BU:GU ratio for balanced beer?
Sources & references
Methodology & trust
Cooking calculator with its formula verified automatically against American Homebrewers Association (AHA) — IBU Calculations & Hop Utilization, per our editorial policy and methodology.
Updated: July 2026. Parameters are verified periodically against the cited sources.
Calculations run 100% in your browser. We do not store or transmit your data.
Indicative results. For critical decisions, consult a professional.
Rodríguez, M. (2026). Beer IBU Calculator — Tinseth Formula. Hacé Cuentas. https://hacecuentas.com/en/ibu-beer-hops-tinseth
Content licensed under CC-BY 4.0 — reuse it citing the source with a link to Hacé Cuentas.