Reading flour: W-values, P/L, protein %

If you've bought professional pizza flour from an Italian supplier, you've seen the numbers on the bag: W 280, W 300, W 360. They mean something specific. Knowing what they mean lets you pick the right flour for the fermentation length you're planning, instead of guessing or copying someone else's recipe.

The two main numbers are W-value (a measure of gluten strength) and the P/L ratio (a measure of dough balance: toughness vs. extensibility). Together they tell you almost everything you need to know about how a flour will behave in pizza dough.

What W-value actually measures

W-value comes from a test run on a device called an alveograph (Chopin Alveograph, invented in France in the 1920s). The test takes a small disc of dough, inflates it with air until it bursts, and measures the work required. A flour that can withstand more inflation before bursting has stronger gluten: a higher W-value.

W-value correlates roughly with protein content but isn't the same thing. A flour can have high protein but weak gluten quality (low W) or moderate protein but strong gluten quality (higher W) depending on the wheat variety and milling.

The W-value scale

Italian flours are sorted into rough strength categories by W-value. These are the conventions:

• W 90–160: weak flour. Used for pastry and biscuits. No use in bread or pizza.
• W 160–250: medium flour. Suitable for short-fermentation breads and same-day pizza dough. Most generic supermarket 00 flour falls here.
• W 250–320: strong flour. The standard zone for Neapolitan pizza dough fermented 8–24 hours. AVPN recommends this range.
• W 320–380: very strong flour. Suitable for long cold ferments (48–72 hours) and for pizza dough that needs to hold up under heavy toppings.
• W 380+: specialty flour. Used for very long fermentations (panettone, some natural-leavened pizza).

Higher W doesn't mean better. It means stronger. A flour that's too strong for your fermentation length produces a tough, springy dough that resists stretching. A flour that's too weak produces a slack, tearing dough that can't survive long fermentation.

Match W to fermentation length

The simplest rule of thumb in pizza:

• Same day (4–8 hours total): W 220–260
• Overnight (12–24 hours): W 260–300
• 24–48 hours cold ferment: W 300–340
• 48–72 hours cold ferment: W 340–380
• Beyond 72 hours: W 380+ or sourdough leaven

The reason: long fermentation breaks down gluten. A weaker flour fermented for 48 hours will degrade past usability; the dough becomes slack and tearing. A stronger flour fermented for 4 hours won't have time to develop full extensibility; the dough fights back when you try to stretch it.

The P/L ratio

The same alveograph test that produces W-value also produces two other measurements: P (resistance to deformation, tied to dough strength) and L (extensibility, tied to how far the dough stretches before breaking). The ratio P/L tells you whether a flour leans toward toughness or extensibility.

• P/L below 0.5: very extensible, weak structure. Slack, hard-to-handle dough. Generally not desirable for pizza.
• P/L 0.5–0.65: the sweet spot for most pizza. Enough structure to hold shape, enough extensibility to hand-stretch without tearing.
• P/L 0.65–0.85: balanced toward strength. Good for high-hydration doughs and very long ferments.
• P/L above 0.85: tough and elastic. Springs back when stretched. Better for breads with heavy structure (bagels, dense rye) than for pizza.

A flour with W 280 and P/L 0.55 will handle differently from a flour with W 280 and P/L 0.75. The first is more extensible, the second more elastic. Both are "strong" by W-value but they behave very differently in your hands.

Protein percentage as a proxy

Most non-Italian flour bags don't show W-value or P/L. They show only protein percentage. Protein is a crude proxy for gluten strength but it's what's available.

• Protein 9–10.5%: weak. Cake flour, pastry flour, soft Italian 00 (pasta-grade).
• Protein 10.5–11.5%: medium. Typical all-purpose flour. Suitable for short pizza ferments.
• Protein 11.5–13.5%: strong. Bread flour, pizza-grade Italian 00. The standard zone for serious pizza making.
• Protein 13.5–15%: very strong. Specialty bread flours. Excellent for long ferments and high-hydration pizza.

If you can find an alveograph-certified Italian 00 flour, use the W-value and P/L. If you can only find a flour with a protein percentage, target 12–13.5% for most home pizza making.

Common pizza-grade flours and their numbers

These are the flours most commonly cited by serious home pizza bakers (numbers are nominal; actual lot-to-lot variation is real):

• Caputo Pizzeria (blue bag): W ~280, P/L ~0.55, protein 12.5%. The standard. Aimed at 8-24 hour fermentation.
• Caputo 00 Cuoco (red bag): W ~330, P/L ~0.6, protein 13%. Stronger, designed for longer fermentations.
• Caputo 00 Saccorosso (red sack): W ~380, P/L ~0.6, protein 13%. Very strong, for very long ferments.
• Le 5 Stagioni Pizza Napoletana: W ~270, P/L ~0.55, protein 12%. Comparable to Caputo Pizzeria.
• King Arthur Bread Flour (US): protein 12.7%, no W-value listed but estimated equivalent to W 270-280. Suitable for moderate-length pizza ferments.
• King Arthur Sir Lancelot: protein 14.2%, very strong. Equivalent to W 350+ flour.

How to choose for your situation

Three questions to ask:

1. 1.How long will you ferment? Short (4–8 hours) → moderate W (220–270). Long (48+ hours) → high W (320+).
2. 2.What hydration? Higher hydration (70%+) needs stronger flour to hold structure. Lower hydration (60–65%) is forgiving on flour strength.
3. 3.Hand-stretch or rolling pin? Hand-stretching needs an extensible flour (P/L 0.5–0.6). Rolling out works fine with stronger, more elastic flours.

What the W-value doesn't tell you

W-value and P/L are useful but incomplete. Three other things matter:

• Wheat variety. Different wheats produce different flavor profiles even at the same W-value. Italian 00 from Italian-grown wheat tastes different from American flour with the same numbers.
• Mill freshness. Flour milled six months ago absorbs water differently than the same flour milled last week. Lot-to-lot variation in big-brand flours is real.
• Falling number (a measure of enzyme activity). Affects dough behaviour and crust browning. Rarely listed on consumer bags.

These factors mean two flours with identical W-values can still behave noticeably differently. The numbers narrow your choices; experience refines them.

The takeaway

W-value tells you gluten strength. P/L tells you balance. Match W to your fermentation length: stronger flour for longer ferments. For most home pizza making, W 270–320 with P/L 0.5–0.65 covers 90% of cases. If you can only find a protein percentage, target 12–13.5%. The exact brand matters less than getting the strength right for your timeline.