August 26, 2026 Steven Eaton

Danger vs Warning vs Caution Signs (2026 Guide)

How do you choose between a danger, warning and caution sign?

Short answer: The signal word encodes how certain the harm is, not how unpleasant it would be. Under ANSI Z535, DANGER means the hazard will cause death or serious injury if not avoided, WARNING means it could, and CAUTION means it could cause minor or moderate injury. NOTICE is not a hazard word at all — it covers practices unrelated to personal injury.

Published August 27, 2026

Almost every facility has a sign wearing the wrong word. Usually it is a DANGER header on a hazard that is merely possible — a well-meant escalation that feels responsible and quietly does damage. This guide sets out the danger vs warning vs caution hierarchy as the standards define it, shows where OSHA's older three-class system maps onto the four-level ANSI ladder, and gives a two-question test that assigns the right word in about ten seconds.

The signal-word definitions come from the ANSI Z535 series, principally Z535.2 for facility and environmental signs. The OSHA sign classes come from 29 CFR 1910.145 and 29 CFR 1926.200. If you need the regulatory frame first, start with our OSHA safety sign requirements guide.

Why this matters.
Signal-word inflation is self-defeating. When DANGER appears on a slippery step, a warm pipe and a live 480-volt cabinet, workers learn that the red header carries no information — and the one sign that genuinely meant "this will kill you" gets the same glance as the other two. OSHA's wording duty at 1910.145(e)(2) requires sign copy to be "accurate in fact," which makes a misclassified header a defect in its own right, not merely a stylistic choice.

The distinction that actually decides it: certainty, not severity

Most people reach for the signal word by asking "how bad is this?" That question cannot separate DANGER from WARNING, because both describe death or serious injury. The separating variable is certainty of outcome if the hazard is not avoided.

If a person makes contact with the hazard and death or serious injury is the expected result — not a possibility, the expected result — the word is DANGER.
If contact could produce death or serious injury but often would not, the word is WARNING.
Only when the realistic worst case drops to minor or moderate injury does the word become CAUTION.

This is why DANGER is rare in a well-signed building. ANSI reserves it for the most extreme situations. An energised 480-volt bus bar with an exposed conductor earns it. A wet floor does not, however badly a fall can end.

The four signal words, as the standard defines them

Signal word	Panel colors	Definition	Alert symbol?
DANGER	Safety white letters on safety red	A hazardous situation that, if not avoided, will result in death or serious injury. Limited to the most extreme situations.	Yes
WARNING	Safety black letters on safety orange	A hazardous situation that, if not avoided, could result in death or serious injury.	Yes
CAUTION	Safety black letters on safety yellow	A hazardous situation that, if not avoided, could result in minor or moderate injury.	Yes
NOTICE	Safety white italicized letters on safety blue	The preferred signal word for practices not related to personal injury — property damage, security, sanitation, housekeeping rules.	No — the safety alert symbol must not be used with NOTICE.
SAFETY INSTRUCTIONS	Safety white letters on safety green	General safe-work-practice instructions, reminders of proper procedure, and the location of safety equipment.	No

The safety alert symbol — an equilateral triangle enclosing an exclamation mark — is what marks a message as being about personal injury. It accompanies DANGER, WARNING and CAUTION. Its absence from a NOTICE header is not a design shortcut; it is the mechanism that tells a reader "this is a rule, not a hazard."

One historical wrinkle worth knowing when you audit old stock. Earlier ANSI wording defined DANGER as an "imminently hazardous situation" and WARNING as a "potentially hazardous situation." Current editions dropped those qualifiers in favour of the cleaner will/could construction. A sign carrying the older phrasing is not wrong — it is simply from a previous edition, and the classification logic behind it is unchanged.

Two words that look like signal words and are not

"Attention." It has no definition in Z535 and no standing in 1910.145. It communicates urgency without communicating severity, which is the one thing a signal word exists to do.

"Important." Same problem, with the added defect that it invites use on genuine hazards where NOTICE or CAUTION is required. If the message concerns property or procedure, the word is NOTICE. If it concerns a person's body, it is one of the three hazard words.

Where OSHA's three classes sit against the four ANSI words

OSHA's general-industry taxonomy predates the ANSI ladder and has three classes, not four. Mapping them is the step most signage programs skip.

OSHA class (1910.145(c))	Nearest ANSI signal word	Where they diverge
Danger — immediate danger, special precautions necessary	DANGER	Close match. OSHA's "immediate" and ANSI's "will result" are doing the same work.
— no equivalent class —	WARNING	The gap. 1910.145(c) has no Warning sign class. OSHA recognises a Warning tag at 1910.145(f)(7) as an optional intermediate level, and construction sites can reach WARNING through 1926.200's reference to ANSI Z535.2-2011.
Caution — potential hazards, unsafe practices	CAUTION	OSHA's Caution is wider — it absorbs everything ANSI would split between WARNING and CAUTION, because OSHA has no middle rung.
Safety instruction — general instructions and suggestions	SAFETY INSTRUCTIONS (and, for non-injury rules, NOTICE)	ANSI splits OSHA's single class in two, separating safe-practice instruction from property-and-procedure messaging.

The practical consequence: an OSHA CAUTION sign is not the same thing as an ANSI CAUTION sign. A hazard that could kill but probably would not is OSHA Caution and ANSI WARNING. Mixing the two vocabularies in one building — some signs on the OSHA ladder, some on the ANSI ladder — produces a set where yellow means two different severities depending on which vendor supplied the sign. Pick one system per site and document the choice. The trade-offs are laid out in OSHA vs ANSI safety signs.

A two-question test for assigning a signal word

Run these in order. They resolve the great majority of real cases without debate.

Is this message about a person's body, or about property and procedure? If property, security, sanitation or housekeeping — stop. The word is NOTICE, with no safety alert symbol. If it is an instruction on safe practice or the location of safety equipment, it is a SAFETY INSTRUCTIONS sign. Only if a person can be hurt do you continue.
Assume a worker fails to avoid the hazard. What is the realistic outcome?
- Death or serious injury is the expected result → DANGER.
- Death or serious injury is possible but not the usual outcome → WARNING.
- The realistic worst case is minor or moderate injury → CAUTION.
Sanity-check the DANGER count. Tally the DANGER signs in the area you just assessed. If more than a small fraction carry the red header, re-run question two on each — escalation has crept in.
Write the hazard, the consequence and the avoidance. A compliant sign tells the reader what the hazard is, what happens if it is not avoided, and what to do instead. "DANGER — High Voltage" fails the third part; "DANGER — High voltage inside. Will cause death or serious injury. Authorised personnel only, lockout required before opening" satisfies all three and meets the 1910.145(e)(2) duty to be concise and accurate.

Five misuses that quietly destroy sign credibility

DANGER on a possible hazard. The most common defect and the most corrosive. It teaches the workforce to discount red.
CAUTION on a potentially fatal hazard. The mirror-image error, and the more legally exposed one. Under the ANSI ladder, a hazard that could kill is never CAUTION.
NOTICE carrying the safety alert symbol. A direct conflict with the standard, and it muddies the one visual cue that separates hazard messages from rules.
A signal word with no consequence statement. A header alone conveys severity but not the hazard, which is exactly the information a reader needs to act.
Signs that are factually stale. A sign naming a removed machine, a discontinued cartridge or a superseded standard fails "accurate in fact" no matter how well its header was chosen. This is the highest-yield thing to look for on a signage walk.

Worked example: three hazards in the same building

A food-processing plant, three hazards within fifty metres of each other, each assessed with the two-question test.

The 480-volt motor control centre

Question one: about a person's body. Question two: an unqualified worker opening an energised MCC cabinet faces arc flash and shock whose expected outcome is death or serious injury. DANGER. The sign should name the hazard, the consequence and the avoidance — energised equipment, arc-flash and shock hazard, qualified persons only, appropriate PPE and an established electrically safe work condition before opening. The underlying process is covered in electrically safe work condition and the standard behind it in what is NFPA 70E arc flash safety.

The ammonia compressor room door

Question one: about a person's body. Question two: a release could be fatal, but entry on an ordinary day is not. Death is possible, not expected. WARNING on the ANSI ladder — which, in a general-industry plant using OSHA's three classes, has to be posted as a Caution sign or supplied under the ANSI format. This is the mapping gap made concrete. Anyone signing a space like this should also read permit-required confined space requirements, because the posting duty may come from 1910.146 rather than from 1910.145.

The wash-down corridor

Question one: about a person's body. Question two: a slip on a wet tiled floor realistically produces a bruise or a sprain; serious injury is possible but not the expected outcome of the hazard as it normally presents. CAUTION — and because the hazard is temporary rather than permanent, the right instrument is usually a portable floor sign rather than a wall-mounted one. Background in are wet floor signs required by OSHA, with formats compared in best wet floor signs and programme context in custodial worker safety guide.

Three hazards, three different headers, one consistent rule. That is what a defensible signage programme looks like from the inside.

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Frequently asked questions about danger, warning and caution signs

What is the difference between a danger and a warning sign?

Certainty of outcome. DANGER indicates a hazardous situation that will result in death or serious injury if not avoided; WARNING indicates one that could. Both describe potentially fatal hazards — the word chosen states how likely that outcome is.

What is the difference between a warning and a caution sign?

Severity of the realistic worst case. WARNING covers hazards that could cause death or serious injury; CAUTION is limited to hazards whose realistic worst case is minor or moderate injury. A hazard that could kill is never correctly labelled CAUTION under ANSI Z535.

What are the four ANSI signal words?

DANGER, WARNING, CAUTION and NOTICE. The first three are hazard-alerting and carry the safety alert symbol; NOTICE addresses practices not related to personal injury and must not carry the symbol. A fifth header, SAFETY INSTRUCTIONS, is used for general safe-practice and safety-equipment-location messages.

What color is a warning sign?

Under ANSI Z535, a WARNING header is safety black letters on a safety orange panel. Orange is the colour that distinguishes WARNING from the red of DANGER and the yellow of CAUTION.

What color is a notice sign?

Safety white italicized letters on a safety blue background. The italics and the blue are both deliberate — together with the absence of the safety alert symbol they signal that the message is a rule rather than a hazard.

Does OSHA recognise warning signs?

Not as one of its three general-industry sign classes. 29 CFR 1910.145(c) names Danger, Caution and Safety Instruction signs only. OSHA does define a Warning tag at 1910.145(f)(7) as an optional level between Caution and Danger, and construction sites can use the ANSI four-level system via 1926.200's reference to ANSI Z535.2-2011.

When should I use a danger sign?

Only where a worker who fails to avoid the hazard should be expected to die or be seriously injured — exposed energised conductors, unguarded fall edges, atmospheres immediately dangerous to life or health. ANSI limits DANGER to the most extreme situations, so a well-signed facility has few of them.

When should I use a notice sign instead of a caution sign?

When nobody can be physically hurt by ignoring the message. Equipment-handling rules, security restrictions, sanitation requirements and housekeeping standards are NOTICE material. If ignoring the sign can injure a person, it is a hazard sign.

What is the safety alert symbol?

An equilateral triangle enclosing an exclamation mark, placed with the signal word to indicate that the message concerns personal injury. It is used with DANGER, WARNING and CAUTION, and must not be used with NOTICE.

Is "attention" a valid signal word?

No. "Attention" and "Important" have no definition in ANSI Z535 and no standing in 1910.145. They convey urgency without severity, which defeats the purpose of a signal word. Use NOTICE for non-injury messages and the three hazard words for everything else.

Can I use both OSHA-format and ANSI-format signs in the same facility?

You can, and both are legally acceptable, but it is a poor idea. The two systems assign different meanings to yellow — OSHA Caution absorbs hazards that ANSI would split between WARNING and CAUTION. A mixed set makes colour unreliable as a severity cue. Choose one vocabulary per site and record the decision in the written programme.

Why does the same hazard get a different word on a product label?

Product safety labels follow ANSI Z535.4 rather than Z535.2, and chemical containers follow OSHA's Hazard Communication standard, which uses only "Danger" and "Warning" as GHS signal words with a different assignment logic. See GHS pictograms and HazCom labels explained for the container-label system.

How many danger signs should a facility have?

There is no target number, but the ratio is diagnostic. DANGER should be the rarest header in the building. If it is the most common, the set has been escalated and the word has stopped carrying information.

Do signal words apply to tags as well as signs?

Yes. Under 1910.145(f)(4) every accident prevention tag must carry a signal word and a major message, be legible at five feet, and be attached so it cannot be unintentionally removed. OSHA names Danger, Caution, Warning and Biological Hazard tags at 1910.145(f)(5) through (f)(8).

Does a sign have to state the consequence?

ANSI Z535.2 expects a hazard sign to communicate the nature of the hazard, the consequence of not avoiding it, and how to avoid it. OSHA's requirement at 1910.145(e)(2) is that wording be concise, easily understood, positively phrased and accurate in fact. A bare header with no message satisfies neither well.

Which system should a general-industry plant standardise on?

Most facilities are better served by the ANSI four-level system, because the extra rung prevents the compression that forces genuinely life-threatening hazards onto a Caution sign. General industry should be aware that 1910.145 incorporates ANSI Z535.1 for colours rather than Z535.2 for layout, so the compliance file should cite the OSHA class the sign satisfies as well as the ANSI format it follows.