Montana Knife Laws
Montana retitled its concealed weapon law in 2017 to cover firearms, so a knife may now be carried openly or concealed at any length. Automatic knives lost their blade length cap in 2019. Since 3 April 2019 the state has had knife preemption, with one carve-out: a local government may still restrict knives on property it owns or leases. Schools bar blades of four inches or more.
This is not legal advice, and we are not lawyers. It is a plain reading of published summaries and the statutes they cite, kept current on a fixed schedule. Local ordinances are frequently stricter than state law and are not all captured here. Check the statute, and check your city, before you carry.
Montana knife law at a glance
| Concealed carry blade limit | No blade length governs. Montana retitled its concealed weapon law in 2017 to cover firearms, so any knife may be carried openly or concealed. |
|---|---|
| Automatic and switchblade knives | Legal. The blade length cap was removed in 2019. |
| Knife types banned outright | None outright. Blades of four inches or more, swords and straight razors are barred in school buildings. |
| Statewide preemption | Yes, since 3 April 2019. A local government may still restrict knives on property it owns or leases. |
| The statutes | Montana Code Annotated 45-8-352 and 45-8-361 — read them |
Source last revised 26 February 2021
Next review 15 November 2026
How fresh this is, and how you can tell
Two dates sit above, and they are not the same thing. Checked by us is the last time a person went back to the sources and confirmed this page still matches them. Source last revised is when the American Knife and Tool Institute last updated its own Montana page. A 2021 revision date is not automatically wrong — it usually means nothing has changed since — but it does mean nobody had looked recently, and that is exactly the gap this page exists to close.
Crossing the Montana state line
Knife law stops at the border and the next state does not have to agree with this one. If you drive, these are the states you are most likely to carry into, and what changes when you do.
| State | Automatic knives | Concealed blade limit |
|---|---|---|
| Idaho | Legal | No blade length governs for ordinary carry. Six inches is the number that matters in a courthouse, jail or juvenile detention facility, where a longer concealed blade is barred. Permitless carry applies from 18. |
| Wyoming | Legal | No blade length governs, and open carry is unrestricted. The concealed deadly weapon rule carries exceptions from 21 for people without violent crime or drug convictions. |
| South Dakota | Legal | No state blade length governs; concealed carry is lawful unless you carry with intent to commit a felony. The city rule is what is likely to catch you. |
| North Dakota | Legal with conditions | Five inches. A blade of five inches or more, and any switchblade or gravity knife, counts as a dangerous weapon for concealed carry. A North Dakota concealed weapon license lifts that. |
A knife that is lawful in your pocket at home can be unlawful the moment you cross, and nobody stops you at the line to tell you. The map for all fifty states covers the rest.
Common questions about Montana knife laws
What size knife is legal to carry in Montana?
No blade length governs. Montana retitled its concealed weapon law in 2017 to cover firearms, so any knife may be carried openly or concealed.
Are switchblades legal in Montana?
Legal. The blade length cap was removed in 2019.
Which knives are banned outright in Montana?
None outright. Blades of four inches or more, swords and straight razors are barred in school buildings.
Does Montana have knife preemption?
Yes. Montana has statewide preemption, which means a city cannot write its own stricter knife ordinance. One rule covers the whole state, and that is most of what preemption is worth.
Can I keep a knife in my car in Montana?
Where a state has a concealed carry limit, a knife in a glovebox or a door pocket is generally treated as concealed. Read the concealed line above and apply it to the vehicle. If that line says concealment is not the issue in this state, the vehicle is not the issue either — but where you drive to still is, because schools and courthouses are barred everywhere.
Where this comes from
Two independent sources, cross-checked against each other, and the statute text where they disagree. The automatic knife column is the American Knife and Tool Institute’s state automatics table, checked against Knife Rights’ own switchblade legality table and their legislative update log. Everything on a state page is quoted or closely tracked from that state’s AKTI page, and we print the date AKTI last revised it so you can see for yourself how fresh the underlying work is.
Where a source is older than a change we know about, we say so on the page rather than quietly leaving the old answer up. That is the whole reason this is checked every two months.
Elsewhere on Popular EDC
The knife law map for all fifty states, the knife steel comparison chart for choosing the blade itself, and every Popular EDC tool in one place.
Data updated September 2026. Montana knife law checked against the published sources on 15 September 2026, and due for review again on 15 November 2026.