What is the FDA threshold for gluten-free?

Less than 20 parts per million (ppm) of gluten. Under 21 CFR 101.91, any food labeled “gluten-free,” “no gluten,” “free of gluten,” or “without gluten” must contain under 20 ppm. The FDA set 20 ppm because it is the lowest level that can be reliably detected with validated analytical methods, and it matches the international Codex standard.

Is gluten-free certification required by law?

No. In the U.S., certification is voluntary. What is legally binding is the FDA labeling rule: any product using a gluten-free claim must meet the under-20-ppm threshold, whether or not it is certified. Certification adds independent verification and a recognized mark, but you can label a product gluten-free without it as long as you meet the rule.

What is the difference between gluten-free certification and the FDA gluten-free label?

The FDA label is a legal claim you can make yourself once your product meets the under-20-ppm rule. Certification is a voluntary third-party program that audits your controls and testing, sometimes against a stricter limit like 10 ppm, and grants a recognized mark. One is a regulatory floor; the other is independent proof plus a trusted logo.

How is gluten measured in food?

With validated analytical methods, most commonly the R5 ELISA, run on finished product. Because 20 ppm is a very low level, testing confirms that your controls worked rather than replacing them. For fermented or hydrolyzed foods, current methods cannot reliably measure gluten, so the FDA instead requires records showing the food was gluten-free before fermentation or hydrolysis.

Does gluten-free mean wheat-free?

No. Wheat-free means no wheat, but rye and barley also contain gluten and contain no wheat. A product can be wheat-free and still fail a gluten-free claim if it contains rye or barley ingredients or is cross-contacted with them. Gluten-free covers wheat, rye, barley, and crossbred grains like triticale.

Can a naturally gluten-free food be labeled gluten-free?

Yes, as long as it meets the under-20-ppm limit. Inherently gluten-free foods like plain rice, fruit, or bottled water can carry the claim, but you still have to control cross-contact so unavoidable traces stay under 20 ppm. Ingredients like oats or spices that are naturally gluten-free can still arrive cross-contacted from a supplier’s facility, so supplier verification matters.

How do plants keep gluten under 20 ppm on shared equipment?

Through segregation, production sequencing, and validated cleaning. Running gluten-free products first after a full cleaning, dedicating utensils and storage, controlling airborne flour, and proving the changeover cleaning repeatably gets equipment under the threshold. Finished-product testing then verifies the controls held. Dedicated lines are the strongest option; scheduling plus validated sanitation is the common alternative.

Gluten-Free Certification

The FDA sets the number; third-party programs prove you hit it. What the 20 ppm threshold means on the floor, and how to build controls that hold.

Gluten-free certification is voluntary third-party proof that a food meets a defined gluten threshold, in the U.S., the FDA’s limit of less than 20 parts per million, through audited controls and validated testing, letting you carry a recognized certification mark on the package. The underlying labeling rule applies to every product that says “gluten-free,” certified or not.

Two things get tangled here: the federal rule that governs the words “gluten-free” on a label, and the private certification programs that add a mark and an audit on top. They are related but not the same. This guide separates them, explains where the 20 ppm number comes from, and walks through the controls that actually decide whether a plant can hold that number, which is where most of the real work is.

What is gluten-free certification?

Gluten-free certification is a voluntary program run by a third-party organization that verifies a product meets a specified gluten limit and lets the manufacturer display that organization’s certification mark. Certification typically involves an application, a facility and records review or audit, product testing, and ongoing surveillance including periodic retesting.

It is worth being precise about what certification adds. The legal claim, the right to print “gluten-free”, comes from meeting the FDA rule, and you can make that claim without any certification. What a certification program adds is independent verification and a recognized logo that shoppers with celiac disease trust, often against a threshold at or below the FDA’s. Some programs certify to a stricter limit, such as 10 ppm, and set their own testing frequency. The mark is a marketing and trust asset; the threshold is a food-safety fact.

So a plant faces two related questions. Can we legally label this gluten-free? That is the FDA rule. Should we also carry a third-party mark? That is a commercial decision driven by your customers and the celiac community’s buying habits.

What is the FDA gluten-free threshold?

Less than 20 parts per million of gluten. Under the FDA’s gluten-free labeling rule, finalized in 2013 and codified at 21 CFR 101.91, any food bearing the claim “gluten-free,” “no gluten,” “free of gluten,” or “without gluten” must contain less than 20 ppm of gluten. The FDA chose 20 ppm because it is the lowest level that can be reliably and consistently detected in food using validated analytical methods, and it aligns with the international Codex standard.

The rule sets out how a food qualifies. It must not contain any of the following, unless the resulting food still comes in under 20 ppm:

An ingredient that is a gluten-containing grain, wheat, rye, barley, or a crossbred grain like triticale.
An ingredient derived from those grains that has not been processed to remove gluten.
An ingredient derived from those grains that has been processed to remove gluten but still leaves the food at 20 ppm or more.

A food that inherently contains no gluten, bottled water, plain fruit, or naturally gluten-free grains like rice, can also carry the claim, as long as any unavoidable cross-contact keeps it under 20 ppm. A label that says gluten-free but exceeds the limit is misbranded and subject to FDA enforcement. Note that “wheat-free” is not the same as “gluten-free”: rye and barley are gluten grains that contain no wheat.

One important nuance for fermented and hydrolyzed foods, soy sauce, yogurt, some beers and cheeses, the current test methods cannot reliably measure gluten in those products, so the FDA issued a separate rule requiring manufacturers to keep records showing the food was gluten-free before fermentation or hydrolysis.

The FDA line: a food may be labeled gluten-free only if it contains less than 20 ppm of gluten. Certification programs may hold you to a tighter number.

Which third-party gluten-free programs exist?

Several independent organizations run recognized gluten-free certification programs, and they differ mainly in their threshold and testing regime. The best-known U.S. programs certify at or below the FDA limit, some at 20 ppm, some as low as 10 ppm, and each has its own mark that shoppers recognize.

The details vary, but every credible program shares the same structure:

A defined threshold at or below 20 ppm, applied to finished product.
A facility and records review that examines your ingredient sourcing, cross-contact controls, sanitation, and testing program.
Product testing using a validated method, at certification and on a recurring basis.
Ongoing surveillance periodic retesting, sometimes unannounced, and re-audit on a set cycle.
A license to use the mark, tied to the specific products and facility that were certified.

Choosing a program comes down to which mark your customers and shoppers recognize, whether you can meet the stricter thresholds some programs use, and how their testing frequency fits your production. If a specific retailer sent you looking, ask which certification they accept before you apply, that answer usually decides it.

How do you build a gluten-free program that passes?

You control cross-contact, verify your inputs, and test the output, in that order. A gluten-free claim rarely fails on the recipe; it fails when gluten from a shared line, a shared ingredient, or a supplier’s facility finds its way into a product that is supposed to be clean. The build looks like this:

Map every gluten source in the plant. Walk the flow from receiving to shipping and mark every point gluten enters: gluten-containing ingredients, shared rework, airborne flour, shared totes and utensils, even shared allergen-laden dust in the rafters. You cannot control what you have not mapped.
Segregate. Separate storage for gluten-containing ingredients, dedicated or scheduled equipment, defined production sequencing (gluten-free first, after full cleaning), and controls on shared air handling and dust. Dedicated lines are the strongest control; scheduling plus validated cleaning is the common alternative.
Verify your suppliers. Every ingredient needs a gluten-free specification and supplier documentation, because a “naturally gluten-free” ingredient like oats or spice blends can arrive cross-contacted from the supplier’s own facility. Treat gluten as an allergen-grade input within your allergen management program.
Validate your cleaning. If you run gluten and gluten-free products on shared equipment, prove the changeover cleaning actually gets you under the threshold, not once, but as a validated, repeatable procedure. Swab and test after cleaning until you have the evidence.
Test finished product with a validated method. Use an approved analytical method (the R5 ELISA is the standard for most foods) on finished product, at a frequency that matches your risk. Testing is verification, not control: it confirms the controls worked, batch after batch.
Document everything. Specs, cleaning validations, sequencing records, test results, and corrective actions. This is what an auditor reviews, and what proves the claim if it is ever challenged.

Why does cross-contact matter more than the recipe?

Because 20 ppm is a very small number, and it takes almost nothing to blow past it. Twenty parts per million is roughly 20 milligrams of gluten in a kilogram of food, a trace most people would never see or taste. A film of flour left on a shared mixer, a scoop moved from a wheat bin to a rice bin, or a supplier’s oats grown in rotation with wheat can each push a naturally gluten-free product over the line.

That is why the discipline mirrors allergen management and leans on the same foundation as any food-safety system: strong good manufacturing practices validated sanitation, and the prerequisite programs that keep a plant clean between the critical steps. A gluten-free claim is only as good as the cleaning between the last wheat run and this one.

Gluten enters from ingredients, equipment, air, and suppliers. Controls block it; finished-product testing only verifies the controls held.

It also means the claim lives or dies on records generated every shift: the changeover cleaning that was actually done, the sequencing that was actually followed, the finished-product test that actually cleared. When those live on clipboards, a missed cleaning verification or a backfilled sequencing log surfaces only at audit, or worse, after a recall. Plants that capture changeover, sanitation, and test records digitally at the line get a live, searchable trail instead, so a gap shows up the same shift. That is the paperwork problem Harmony solves for food and beverage plants; one manufacturer replaced paper production logging and automated its daily reporting on exactly that kind of shift data. The certification mark is the reward; the record discipline is the job.

How does gluten-free certification fit your other programs?

It sits on top of your food-safety system, not beside it. The controls that hold gluten under 20 ppm, supplier verification, segregation, cleaning validation, sanitation, testing, are the same controls your HACCP plan and allergen program already demand. Most plants manage gluten as part of allergen control rather than as a separate system, and treat the finished-product test as a verification step.

If you already hold a GFSI-recognized certification like SQF most of the management-system scaffolding is in place; gluten-free certification adds a specific threshold, a testing regime, and a mark. Build it into what you have rather than standing up something parallel. The reader who needs the trace-back side of the picture, proving where a suspect lot went if a test comes back high, should pair this with FSMA 204 traceability because a gluten-free program you cannot trace is a recall you cannot scope.