Ale vs. Lager Fermentation: A Comprehensive Comparison

The short answer: ales use top-fermenting Saccharomyces cerevisiae at about 60 to 72°F (16 to 22°C) and are usually done in one to two weeks, with fruity esters. Lagers use bottom-fermenting Saccharomyces pastorianus at about 48 to 55°F (9 to 13°C), take two to three weeks to ferment, then need weeks of cold lagering for a clean, crisp finish.

	Ale	Lager
Yeast	S. cerevisiae, top-fermenting	S. pastorianus, bottom-fermenting
Temperature	60–72°F (16–22°C)	48–55°F (9–13°C)
Primary fermentation	5–14 days	2–3 weeks
Conditioning	Days to 2 weeks	3–8 weeks lagering near 32–35°F (0–2°C)
Flavour	Fruity esters, fuller	Clean, crisp, malt and hops forward
Diacetyl rest	Built in: hold at temperature 2–3 days after it finishes	Raise to 60–65°F (16–18°C) for 2–3 days
Equipment	Room temperature can work	Temperature control needed

The yeast makes the difference

Ale and lager are defined by the yeast, not by colour or strength. There are black lagers (schwarzbier) and pale ales, and either can be strong.

• Ale yeast (S. cerevisiae) works best warm and makes more esters, the fruity flavours in a pale ale, an English bitter or a Belgian.
• Lager yeast (S. pastorianus) is a natural hybrid of ale yeast and a cold-tolerant wild species. It keeps fermenting in cold wort, where it makes few esters but more sulphur, which fades during lagering.

“Top” and “bottom” fermenting come from old open fermenters, where ale yeast rose into the krausen and brewers skimmed it off, while lager yeast settled. In a modern conical, both end up in the cone.

Side by side: a typical schedule

Stage	Ale	Lager
Pitch	62–64°F (17–18°C)	45–48°F (7–9°C), then let it rise to 50–52°F (10–11°C)
Yeast needed	0.75 million cells per mL per °Plato	1.5 million, about double
Oxygen	8–10 ppm	10–12 ppm
Active fermentation	3–5 days at 64–68°F (18–20°C)	7–14 days at 48–55°F (9–13°C)
Diacetyl rest	Hold 2–3 days after the gravity stops falling	60–65°F (16–18°C) for 2–3 days
Cold	Crash to 32–38°F (0–3°C) for a few days	Lager at 32–35°F (0–2°C) for 3–8 weeks
Grain to glass	About 2–4 weeks	About 5–10 weeks

For a 5 gal (19 L) batch around 1.050, one 11 g sachet of dry ale yeast is about right for an ale, or one fresh liquid pack, ideally with a 1 L starter. A lager needs two sachets of dry lager yeast, or a yeast starter of 2–3 L. Underpitching is the most common reason a lager comes out sulphury or buttery.

How the flavour ends up different

Esters form mostly in the first few days, while the yeast are growing, and warmth drives them up. An ale at 66°F (19°C) keeps some fruit; the same ale at 75°F (24°C) can turn hot and solventy with fusel alcohols. A lager at 50°F (10°C) makes so few esters that the malt and hops carry the beer.

The cold costs time. Lager yeast work slowly, so diacetyl and sulphur take longer to clean up, which is why lagers need the warm diacetyl rest and weeks of lagering. During lagering, yeast and haze drop out and the flavour rounds off.

Where the line blurs

• Ale yeast, fermented cool. Kölsch, altbier and most cream ales use ale yeast at 58–62°F (14–17°C), then cold-condition like a lager. Try our Kölsch or cream ale recipes.
• Lager yeast, fermented warm. California common uses a lager strain at warmer, ale-like temperatures. See our Anchor Steam clone.
• Lager yeast under pressure. At 10–15 psi, lager yeast can ferment at 62–68°F (17–20°C) and stay clean, so a lager finishes in about the time an ale takes. See pressure fermentation.

What you need for each

An ale can ferment in a room that stays around 62–66°F (17–19°C), keeping in mind that fermenting beer runs 5–10°F warmer than the room at its peak. A lager needs to hold 50°F (10°C) for two weeks, warm up for the rest, then sit near freezing for a month or more. That takes a fridge with a controller, or a jacketed fermenter such as a Unitank with a temperature control kit and a glycol chiller. Tap water through the jacket handles ales, but can’t get cold enough to lager.

Frequently asked questions

Can I ferment lager yeast at ale temperatures?

Without pressure, it usually gets fruity. Under 10–15 psi in a pressure-rated fermenter, many lager strains stay clean at 62–68°F (17–20°C).

Can I make a lager with ale yeast?

You can make a clean, crisp ale that gets close: use a very clean ale strain at the bottom of its range, then cold-condition it. It won’t be quite the same.

Which is easier for a first brew?

An ale. It’s faster, more forgiving, and doesn’t need cold storage.

How long should I lager?

An old rule is a week for every 10 points of original gravity, so about five weeks for a 1.048 pilsner. Taste it weekly: when the sulphur is gone and it’s clear, it’s ready.

Is lager stronger than ale?

No. Strength comes from the recipe. Both range from light to very strong.

Related guides

Lagering, the diacetyl rest, how to brew a pilsner, how yeast make beer and how to size a glycol chiller, or use the calculator on our glycol chillers page.