Choosing a yeast for your beer
How to think about yeast strains by attenuation, flocculation, temperature range and flavour profile.
Last updated 30 March 2026 · 8 min read
The four axes
When you read a yeast spec sheet, four numbers matter most:
- Attenuation — % of sugars the yeast will eat. 70-75% is normal for English strains, 78-82% for American clean ale, 82-85% for Belgians and lagers, 85%+ for saison.
- Flocculation — how readily the yeast drops out of suspension when fermentation finishes. High flocculators (S-04, English liquid strains) give clear beer fast but may stall in high-gravity wort.
- Temperature range — manufacturer-published. The lower end is cleaner, the upper end is more ester- and phenol-driven.
- Flavour profile — what the yeast contributes beyond ethanol. Clean ale (US-05) contributes very little; English ale (S-04) contributes light fruit; Belgian (WLP530) contributes pepper-clove phenol and pear-banana ester; lager strains contribute almost nothing flavour-wise but produce light sulphur during fermentation.
Matching yeast to style
| Style family | Default strain | Why |
|---|---|---|
| British bitter, mild, porter | S-04 (English) | Light fruity ester complements malt |
| American IPA, pale, amber | US-05 (clean American) | Hop showcases need a neutral yeast |
| Bohemian/German lagers | W-34/70 | Clean, deep attenuation, classic profile |
| Belgian abbey, dubbel, tripel | WLP530 | Phenolic spice + dry finish |
| Saison | WLP565 / WY3724 | Aggressive attenuation + phenolic dryness |
Pitch rate basics
Underpitching is the most common cause of underwhelming homebrew. As a rough rule:
| Beer strength | Pitch (10ⁱ⁰ cells / L) |
|---|---|
| Standard ale (OG ≤ 1.060) | 0.75 |
| Big ale (OG > 1.070) | 1.5 |
| Lager (any gravity) | 1.5 × the ale rate |
One 11.5 g dry sachet contains roughly 1.2 × 10¹¹ cells. Two sachets handle most 20 L batches, two-and-some for high-gravity or lager.
Related products
- Fermentis SafAle S-04A clean, fast-fermenting English ale strain in dry form — a workhorse for bitters, milds and porters.
- Fermentis SafAle US-05The dry-form American ale workhorse. Clean, neutral, high attenuation — the right choice when you want your malt and hops to do all the talking.
- WLP530 Abbey Ale YeastA Belgian abbey strain producing the classic phenolic-and-fruit profile — peppery clove, banana ester, and a dry finish.
- Fermentis SafLager W-34/70The dry lager standard — a Weihenstephan 34/70 derivative producing clean, slightly sulphury, deeply attenuating ferments. Bohemian Pilsners and Helles start here.