UL 94 / IEC 60695-11

UL 94 Flammability Rating Selector

Compare UL 94 material classifications and review what evidence is still needed before applying a class to a real part. The tool does not make an end-product compliance decision from class, role or thickness alone.

Maintained by Giorgi Gaprindashvili Published June 26, 2026 Updated September 18, 2026 Editorial check September 2026

Compare two material classifications

Requirement-side class

Material-side class

What evidence do I still need?

Part role / location

Governing standard

Min wall thickness

Method based on ANSI/UL 94 (Ed. 7, 2023; rev. Feb 2026) / IEC 60695-11-10 and -11-20 · editorial check September 2026 · revision 1.1

How the ratings are tested

UL 94 uses different small-scale test methods for HB, V and 5V classifications. The classifications describe material behavior under those controlled tests; they do not by themselves establish an end-product requirement.

Common UL 94 material classifications

These six classifications are commonly used for rigid enclosure, structural and insulating plastics. Their test criteria can be compared, but this table is not an end-product compliance ladder.

Verify the exact material listing at the actual part thickness, formulation/color and applicable test family. Thin films and foams use different UL 94 classification families.
Rating	Test	Self-extinguish	Drips
HB	Horizontal, 50 W (20 mm)	Burn rate limited; no self-extinguishing required	Not assessed
V-2	Vertical, 50 W (20 mm)	≤ 30 s after each flame application	Flaming drips allowed (may ignite cotton)
V-1	Vertical, 50 W (20 mm)	≤ 30 s after each flame application	No flaming drips
V-0	Vertical, 50 W (20 mm)	≤ 10 s after each flame application	No flaming drips
5VB	Vertical + plaque, 500 W (125 mm)	≤ 60 s after the 5th application	No drips; plaque may burn through
5VA	Vertical + plaque, 500 W (125 mm)	≤ 60 s after the 5th application	No drips; no plaque burn-through

How the common UL 94 classification group is tested

HB uses a horizontal burning test. V-2, V-1 and V-0 use the 50 W vertical test and differ in burning/afterglow limits and whether flaming drips may ignite the cotton indicator. 5VA and 5VB use the separate 500 W 5V method and add sheet/plaque hole-formation criteria.

UL Solutions describes the ignition source used for 5VA/5VB as approximately five times more severe than the one used for the V and HB tests. That statement is about the defined test source, not a simple 500 W ÷ 50 W severity calculation. These material classifications are useful screening data, not a substitute for the end-product requirement.

Why the exact material listing matters

UL 94 classifications are tied to the tested/listed material conditions, including thickness and potentially formulation or color. A material can show different classifications at different thicknesses, so verify the actual listing for the part instead of assuming a classification transfers from another specimen thickness.

For very thin flexible material, the VTM family may apply; foamed materials use HBF/HF classifications. UL explicitly warns that VTM-0 is not equivalent to V-0, and the same applies to the corresponding VTM-1/V-1 and VTM-2/V-2 pairs.

What UL 94 does not tell you

UL 94 is a small-flame material screening test under controlled lab conditions. It says nothing about smoke density, gas toxicity, heat-release rate, or how a part behaves inside a real assembly fire, and a high rating does not by itself mean the finished product passes its safety standard. Glow-wire tests (common for appliances) and end-product fire tests cover the rest, so treat the UL 94 class as a necessary screen, not the whole fire-safety case.

Worked examples

Examples of how to identify missing evidence without turning the material classification into a product-level pass/fail decision.

Scenario	Result	Why
Need identified by product standard as V-0; material listing shows only V-2 at the actual wall thickness	Evidence mismatch	The available material listing does not show the requested V-0 classification at that thickness. Select a suitable listed material or reassess the requirement from the governing clause.
Material listing shows V-0 at the exact part thickness	Relevant evidence found	The material listing supports that classification at the stated thickness, but the end-product clause, formulation/color and construction still need to match.
Small connector mounted on a rated carrier	Clause review required	This tool does not grant a small-parts exemption. Verify whether the applicable product standard provides one for the actual construction.

How UL 94 relates to other standards

Standard	Relationship	What it means
IEC 60695-11-10 and -11-20	Harmonized with	The IEC small-flame test methods that mirror the UL 94 horizontal-burn and vertical-burn procedures.
ISO 9772 and ISO 9773	Aligned with	The ISO equivalents for cellular (foam) materials and thin flexible materials.
IEC 62368-1 and UL 746C	Referenced by	End-product safety standards that call up a minimum UL 94 class for enclosure and part flammability.

This tool compares UL 94 material classifications and identifies evidence still needed for a real part. It does not determine a universal minimum class, grant small-parts exemptions, or issue a product-compliance result. Verify the applicable product-standard clause and the exact material listing for the actual thickness, formulation/color and test family.

Where engineers use this

Enclosure and housing plastics

Confirming a candidate resin's flammability class meets the product safety standard at the part's real wall thickness, not a thicker reference bar.

Parts near live or arcing nodes

Deciding where V-0 is required versus where V-1 or HB is acceptable around power, connectors and ignition sources.

Material substitution reviews

Checking that a proposed alternate material still holds its rating before a second source is approved.

Frequently asked questions

Does a higher UL 94 rating always satisfy a lower requirement?

Do not use the classification order as an automatic end-product compliance rule. The applicable product standard, material test family, listed thickness, formulation/color and construction conditions still have to match. A 5V, VTM or foam classification also belongs to a distinct test context.

Is V-0 always better than V-2?

V-0 has stricter criteria than V-2 within the 50 W vertical-test family, but the useful question is whether the applicable product requirement and the material listing match. Over-specifying a class is not a substitute for checking the governing clause and construction.

What rating does a fire enclosure need?

This tool does not assign a universal fire-enclosure minimum. The requirement depends on the applicable end-product standard, construction, available energy/ignition scenario and any relevant exceptions. Use the governing clause, then verify the material listing at the actual part conditions.

Why does the same material show several different ratings?

Because the listing is tied to tested conditions such as specimen thickness and can also depend on formulation or color. Verify the exact listing for the material and part conditions rather than treating a resin name as one universal class.

Are 5VA and 5VB on the same scale as V-0?

They belong to the same common rigid-material classification grouping but use the separate 500 W 5V method and plaque/sheet hole-formation criteria. Do not treat 5VA/5VB as an automatic end-product substitute for a V requirement without checking the governing clause and material listing.

Does a UL 94 rating mean my product is fire-safe?

No. It is a material-level screening test; it says nothing about smoke, toxicity or heat-release rate, and it does not replace glow-wire or end-product fire testing. Treat it as one required screen within the product standard, not proof of compliance on its own.

Related tools and standards

UL 94 standard explainedWhat each rating means and the test behind it Creepage & clearance calculatorMaterial group (CTI) and spacing for the same insulation barrier IEC 62368-1 explainedThe hazard-based standard that calls up these ratings

Sources: UL 94, Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances · UL Solutions - Combustion (Fire) Tests for Plastics. Verify against the current edition.