TSA vs CATSA: the rules that actually change at the border
Guide
The famous rule — 3.4 oz / 100 ml in one quart bag — is literally identical on both sides of the US–Canada border, which is exactly why the differences blindside people. This page collects every divergence we have verified against the two authorities’ own item pages, with links to the full ruling for each. Nothing here is opinion; every line traces to TSA’s or CATSA’s published list.
On this page · 8 sections
The 10 rules that actually change
Mostly status-quo — but each row below has turned into a real confiscation for someone who assumed the rules were shared.
| Item | 🇺🇸 TSA (US) | 🇨🇦 CATSA (Canada) |
|---|---|---|
| Bowling balls | Checked only — classified as bludgeon-capable (policy updated Feb 2025) | Permitted in the cabin |
| Eye drops | ≤ 3.4 oz in the liquids bag; more only as declared medication | Essential non-prescription med — over 100 ml allowed when declared |
| Dry powders (spices, supplements) | Over 12 oz (350 ml) goes in a separate bin — no total cap | Hard cap: all powders together ≤ 350 ml/g in carry-on |
| Baby powder | Same 12 oz bin rule as other powders | Same 350 ml cap — with NO baby exemption (formula and meds are exempt) |
| Scissors | Blades under 4 in (10.2 cm) from the pivot | Blades 6 cm (2.4 in) or less — stricter |
| Pepper spray | One ≤ 4 oz can, checked, ≤ 2% CS with safety | Never in either bag; some types illegal to possess — police are notified |
| Cannabis & CBD | Federally illegal; TSA refers discoveries to police | Domestic flights OK within possession limits — the border is criminal either direction |
| Ice skates | Both bags, blades attached or not | Detachable blades → checked; loose blades never in cabin |
| Matches (safety) | One book, cabin only, never checked | Cabin permitted; checked only with air-carrier approval |
| Candles | Gel-type candles: banned from the cabin (treated as gels) | Candles permitted in carry-on — the page carves out no gel exception |
Verified against both authorities’ item pages on July 30, 2026 — each item link carries its own sources and dates.
The outright contradiction: bowling balls
There is exactly one everyday item where the two countries give flatly opposite cabin answers. In February 2025, TSA moved bowling balls into the bludgeon category — a 14 lb sphere is a club with a thumb hole, the logic goes — while CATSA kept them cabin-legal. Outbound from Canada your ball can ride the overhead; the same trip booked home-to-home through a US airport requires checking it. Nobody in a bowling forum believes this until the checkpoint proves it.
Canada’s powder cap — the silent trap
The US asks about big powders one at a time: a container over 12 oz earns a separate bin, but there is no total limit. Canada instead caps all powders and granular materials together at 350 ml/g in the cabin — roughly a soda can. That total mixes everything: spices, protein and creatine, talc, air-activated hand warmers, and baby powder — which, brutally, has no baby exemption even though formula does. The family that sails through a US checkpoint can overflow Canada’s cap on the return leg without changing a thing in the bag.
Medication & baby items: the small print differs
Both countries let medically necessary liquids exceed the limit when declared — but they name different honorees. CATSA puts eye drops explicitly on the essential non-prescription list, so a 120 ml bottle declared at a Canadian checkpoint is legal; TSA’s item page still caps undetermined eye drops at 3.4 oz unless you assert the medical exemption. Inhalers route through the normal liquids bag in Canada until they exceed 100 ml; TSA treats them as medication from the start. And while breast milk flies child-free under both authorities, other baby items over 100 ml require an infant actually traveling under CATSA’s wording — TSA’s does not.
Items Canada treats more strictly
Pepper and bear spray top the list: the US has a narrow checked-bag pathway for one small can; Canada bans it in both bags — and for some formulations, mere possession is a crime with a police-notification protocol at the checkpoint. Cannabis inverts: domestically legal in Canada within possession limits, federally illegal everywhere in the US, and a criminal offence crossing the border in either direction — including all CBD. Safety matches show the friendliest split: both allow one book in the cabin, while Canada alone offers a carrier-approved route for checked matches that the US does not.
What is genuinely identical
The big three never change: liquids (3.4 oz / 100 ml, one bag per person), lithium batteries (cabin only, spares protected), and bludgeon-class sports gear (bats, golf clubs, ski poles — checked only). Knives, box cutters, and tools over 7 inches check in both countries. Both let EpiPens and other medication exceed liquid limits when declared, and both screen small pets the same way: carrier through the X-ray, animal in your arms through the metal detector.
Whose checkpoint are you even at?
Security follows the departure country: CATSA in Toronto, TSA in New York. The twist is US preclearance — at Vancouver, Toronto Pearson, Montreal, Calgary and other major Canadian airports you clear US customs before boarding, so a Canada-legal item (say, 150 ml of declared eye drops) waves through CATSA and then presents itself to CBP an hour later under US import logic. That sequence is legal for medication — just slower — but it is exactly where Canadian-legal cannabis becomes a US federal problem: cross the preclearance hall with it and you are at a US border post on Canadian soil. The liquids allowance never changes along the way; jurisdiction does.
FAQs
Is airport security stricter in Canada or the US?
Neither — they are differently strict. Canada is tighter on scissors (6 cm vs 4 in), total powders (350 ml cap), pepper spray (never, police referred), and loose skate blades. The US is tighter on bowling balls (checked only) and cannabis (federally illegal everywhere). The liquids rule itself is identical: 3.4 oz / 100 ml containers in one quart/1 L bag.
Can I fly domestically in Canada with cannabis?
Yes — within the Health Canada public-possession limit, on domestic flights only, with liquid/topical forms inside your 1 L liquids bag. Never cross any international border with it: taking any amount into or out of Canada is a criminal offence, and it is federally illegal to bring into the US.
I bought pepper spray for bear country in Canada — can I fly with it?
No. CATSA prohibits pepper spray in both bags, and several formulations are illegal to possess in Canada at all — checkpoint protocol is a police notification. Buy bear deterrent at your Canadian destination instead.
Whose security rules apply when I fly Toronto → New York?
CATSA screens you in Toronto by Canadian rules; when you land you clear US customs — increasingly before departure at airports with US preclearance. Coming home New York → Toronto, TSA rules apply at the US airport and CBSA customs on arrival. The liquids allowance is identical at both checkpoints.
Do I need my baby with me to bring breast milk?
Neither authority requires it for breast milk specifically — both allow it over the liquid limit with or without the child. But CATSA requires an infant (under 2) to be present for other baby items (food, formula, juice) over 100 ml — TSA does not.
Are the TSA and CATSA liquid rules the same?
Effectively yes: every container must be 3.4 oz (100 ml) or less, all inside one quart-size (1 L) clear bag per passenger. The differences live around it — Canada’s total powder cap, the baby-food presence rule, and the ointment-of-choice exceptions they name explicitly.