Beer IBU Calculator (Tinseth Formula)

What this tool does

Hops only bitter beer once their alpha acids are isomerised by boiling, so what counts is not just how many grams go in but how long they boil and how dense the wort is. Glenn Tinseth fitted his formula in the 1990s to measured data, and it is the default in most brewing software: utilisation climbs steeply in the first 30 minutes and levels off after about an hour, and it drops as the gravity rises. A 10-minute addition contributes aroma and only a little bitterness, and the formula ignores hops added after the boil. Other methods such as Rager or Garetz give different numbers for the same recipe, so compare recipes using the same method; the BU:GU ratio near 0.5 is balanced, near 1 is clearly bitter.

Formula

IBU = 1.65 × 0.000125^(G − 1) × (1 − e^(−0.04 t)) ÷ 4.15 × (α × grams × 1000 ÷ litres)

Variables

Worked example

Limitations

• The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
• The default values are typical reference figures, not measurements of your situation. Replace them with your own data whenever you have it.