Someone buys a bag of "00" flour because every pizza recipe mentions it, runs a two-day cold ferment, and finds the dough slack and structureless at shaping. They conclude they did something wrong with the fermentation.
They did not. They used a flour that was never going to hold up over that schedule, and the packet gave them no reason to suspect it, because the number on the front does not describe strength.
This is the most common and most expensive misunderstanding in pizza ingredients, and it takes about five minutes to clear up.
What "00" actually describes
Italian flour type numbers describe how finely the flour is milled and how much of the bran and germ has been removed. The scale runs from finer to coarser, and "00" is at the fine end.
That is all it means. It is a milling classification, not a performance grade.
A "00" flour can be weak or strong. So can a coarser one. The number tells you about texture and extraction, not about how the flour will behave in a two-day dough.
The confusion is understandable. The flours most associated with a famous pizza style happen to be finely milled, so fineness became a proxy for quality in a lot of pizza writing. It is not.
What actually matters: strength
Strength is a flour's ability to develop and hold gluten structure. In practice it governs two things you care about directly:
- How much water the flour will carry while still producing dough with structure rather than a slack mass.
- How long a fermentation it survives before that structure begins to degrade.
Both of those are limits. Push past either and no amount of technique compensates, which is why strength is the constraint behind a great many apparently unrelated failures.
Protein content
Protein percentage is the most widely available proxy for strength, and it appears on a great many packets.
Higher protein generally means more gluten-forming potential, which generally means a stronger flour. It is a useful indicator and it is not a perfect one, because protein quality varies as well as quantity. Two flours at the same protein percentage can behave differently.
Still: if protein content is the only figure you can find, it is a substantially better basis for a decision than the type number.
W value
W value is a milling measure of flour strength derived from a standardised dough-testing instrument. It is the figure professional buyers use, and it captures more than protein percentage alone.
It is also frequently absent from retail packaging, because the retail bag is not aimed at people who know what to do with it. You will often find it on a manufacturer's trade specification sheet even when it is missing from the packet in the shop.
Do not assign one W range to a style without naming the flour maker, formula, and schedule. Use the flour's current technical sheet, then validate it in the planned hydration and fermentation; W is a laboratory measurement, not a guarantee that every dough at that number behaves identically.
Matching strength to schedule length
This is the practical rule, and it is where the whole post lands.
Longer fermentation demands more strength. A flour spends the entire ferment having its structure worked on. A weaker flour runs out of structure sooner, and when it does you get slack dough that will not hold a ball, tears when opened, and does not hold gas through the bake.
Higher hydration also demands more strength, independently. A flour that cannot carry the water produces a soupy mass regardless of mixing.
The two compound. If you raise hydration and extend the schedule at the same time, you reach the limit much faster than you expect, and you will not know which change caused it.
| If you are running | You want |
|---|---|
| A same-day dough | A moderate flour is fine; strength is not the constraint |
| An overnight dough | Moderate to stronger flour |
| A multi-day retard | Stronger flour, and this is where weak flour fails visibly |
| Higher hydration at any length | More strength than the same schedule at lower hydration |
Whatever flour you settle on, record its specification alongside your bake log, so a change of flour is visible when a familiar formula behaves differently.
How to find the number
In rough order of how much you can rely on it:
- The manufacturer's technical data sheet. Usually on their website, often in a trade or professional section. This is the best source and it is more often available than people assume.
- The packet. Protein content is commonly printed, sometimes in a nutrition panel rather than as a headline.
- A retailer's product page. Sometimes carries data the packet omits, though it is worth treating as second-hand.
- Nothing published. This is common, and it is itself information: a flour you cannot match to a schedule is a flour you are using on faith.
When nothing is published
You have two practical options.
Use it once with everything else held constant and record what happened. That gives you a data point about this flour in your kitchen, on your schedule, which is genuinely more useful than a specification you cannot verify.
Test the dough directly. Take a small piece after mixing and rest, and stretch it gently. If it thins out and becomes translucent before tearing, there is structure. If it tears immediately with no thinning, there is not, and that flour will not carry the hydration or the schedule you have given it.
Blending flours
A legitimate technique and a common one. Blending a stronger flour with a weaker one lets you land between them.
Two things to know. The flours together make up the 100% in your baker's percentages, with each given as its own share. And blending is a change like any other, so change the ratio on its own if you want to know what it did.
Lot variation
Flour is an agricultural product and it varies between production runs of the same product. Absorption and behaviour shift.
This is not a reason to abandon specifications. It is a reason to record the flour and, where it is printed, the lot in your bake log, so that when a familiar formula behaves oddly you have somewhere to look. It is one of the six variables in why the same recipe gives different results.
Mistakes to avoid
Buying "00" and expecting strength. The central error this post exists to fix.
Assuming protein percentage and W value are the same thing. Related, not identical. Protein is a proxy; W is a measurement of behaviour.
Extending a schedule without checking the flour. The most common cause of dough that collapses at shaping.
Raising hydration and schedule length together. Change one.
Treating bread flour as a compromise. For several styles, a strong bread flour is the correct choice rather than a substitute.
In Plain English
Italian flour type numbers such as "00" describe milling fineness, not strength. What governs how a flour behaves in pizza dough is its strength, indicated by protein content and more precisely by W value, and strength determines how much water the flour carries and how long a fermentation it survives.
This is for anyone whose long-ferment dough collapsed, or who bought fine-milled flour expecting it to be better and got a worse result.
Use it before you buy flour for a schedule longer than a day, and before you raise hydration. Match strength to schedule length, change one of those at a time, and treat a flour with no published specification as one you are using on faith.
Next step: look up the protein content of the flour you already have. If the manufacturer publishes a technical data sheet, look for a W value too. That number explains more about your dough than anything else on the packet.
Where to go next
- Read the full guide: how to buy pizza ingredients on spec
- The hydration side of the same constraint: pizza dough hydration explained
- The schedule side: how to choose a fermentation schedule
- If the dough already collapsed: over-proofed pizza dough
- Take the specs shopping: how to buy ingredients on spec