Last updated: October 19, 2026
The answer that matters before you buy a bag
A fully packed bag no larger than 40 × 30 × 20 cm is the simplest common dimensional target for a free underseat item on Ryanair, Wizz Air and easyJet. Ryanair and Wizz Air publish that small-bag allowance. easyJet publishes 45 × 36 × 20 cm, so its free bag can be wider and taller. The common target is not an assurance that every item sold as “24 litres” will fit, or that enforcement will be lenient.
The difference between these airlines becomes expensive when you book the outbound flight with one carrier and come home on another. A shopper may buy a bag advertised as “easyJet compliant,” then discover that its fully packed shape exceeds the Ryanair allowance. The answer is to compare all three external dimensions on the strictest leg, not to trust an “airline approved” label.
These are the official limits for the ordinary small bag, not for paid overhead baggage:
| Airline | Free underseat allowance |
|---|---|
| Ryanair | 40 × 30 × 20 cm. Must fit the sizer. Do not apply its separate 10 kg overhead-bag rule to this small item. |
| Wizz Air | 40 × 30 × 20 cm; 10 kg maximum. |
| easyJet | 45 × 36 × 20 cm; 15 kg maximum. You must be able to lift and carry it yourself. |
These facts come from Ryanair’s bag-policy page, Wizz Air cabin baggage rules and easyJet’s cabin baggage policy. Booking-specific baggage entitlements override casual descriptions in a travel blog.
The volume trap: a 23-litre bag can fail a 24-litre-sized rule
The published Ryanair/Wizz Air dimensions describe a geometric 40 × 30 × 20 cm box, whose volume is 24 litres. But an airline does not usually ask whether the volume of your bag happens to be 24 litres. It checks dimensions and fit.
Consider an illustrative backpack whose fully packed exterior is 42 × 29 × 19 cm. Its rectangular volume is approximately 23.1 litres (42 × 29 × 19 ÷ 1000). That is less than 24 litres, yet the 42 cm side exceeds a 40 cm maximum. A product page advertising the correct number of litres would not make it dimensionally compliant.
The opposite misunderstanding is just as common: easyJet’s 45 × 36 × 20 cm box is 32.4 litres geometrically, 35% larger than Ryanair’s 24-litre exterior box. This is not a claim that a real easyJet-labelled backpack holds exactly 35% more usable clothing. Pockets, padding, straps and rigidity change the usable interior, and different shapes can have the same marketed capacity.
Five worked fit examples before you get to an airport
The examples below are hypothetical filled-bag measurements for teaching the method, not physical tests of commercial bags. A “fits” in this table means its dimensions are no greater than the three published size limits; it does not promise sizer approval for a strange shape, protruding components, weight or a different fare.
| Packed dimensions | Dimensional result |
|---|---|
| 38 × 28 × 18 cm | Within all three limits, with some margin. |
| 40 × 30 × 20 cm | At the Ryanair/Wizz maximum; within easyJet’s limit. |
| 42 × 29 × 19 cm | Too long for Ryanair/Wizz; within easyJet’s limit. Litres do not decide fit. |
| 45 × 36 × 20 cm | Over Ryanair/Wizz limits; at easyJet’s maximum. |
| 55 × 40 × 20 cm | Over the free underseat limit on all three. This is overhead-bag territory. |
How to measure: put all your intended possessions inside the bag. Close every compartment. Measure the highest, widest and deepest parts of the bag in its fully packed state, including external bulges. Do not compress it by hand during measurement and assume it will stay that way in the airport sizer. The bag’s listed flat dimensions may not reflect its loaded shape.
A soft-sided bag can sometimes deform enough to fit a physical sizer, but that is not a guaranteed extra allowance. Choose a real margin rather than betting on an unofficial tolerance.
Handles and wheels: a subtle difference not all “comparison charts” explain
easyJet explicitly says its listed dimensions include handles and wheels. Wizz Air’s official cabin-baggage page says its size allowance excludes handles/wheels, with a specific additional wheel projection of no more than 5 cm. Ryanair requires fitting the physical sizer.
For a traveller using all three carriers, it is safer to measure the entire exterior and satisfy the strictest rule rather than seeking every carrier-specific exception. A bag with a hard wheeled base may be much less forgiving than a soft backpack even where the nominal case body looks compliant.
A bag advertised as “40 × 30 × 20 cm excluding wheels” should trigger a question: what are the fully packed dimensions including them? The seller’s answer could determine whether that exact product works across an itinerary.
Overhead bags are a different allowance and their sizes don’t match either
The three airlines offer purchased or fare-included larger cabin bags, but the dimensions are not identical.
- Ryanair: 55 × 40 × 20 cm, 10 kg, through Priority & 2 Cabin Bags or an eligible fare.
- Wizz Air: 55 × 40 × 23 cm, 10 kg, with WIZZ Priority.
- easyJet: 56 × 45 × 25 cm, 15 kg, when a larger bag is booked or your specific fare/membership conditions allow it. Membership alone can carry availability conditions; check the booking entitlement.
Sources: Ryanair, Wizz Air, easyJet. Wizz Air’s distinctive 23 cm overhead depth does not become a 23 cm Ryanair allowance. A hard case sized exactly 55 × 40 × 23 cm may fit Wizz’s paid trolley limit yet exceed Ryanair’s corresponding paid overhead depth by 3 cm.
The bag you carry for free under the seat and the additional bag you purchase to put overhead are separate categories. Priority boarding is not a magic exemption for any size or weight.
When should you pay for luggage rather than replace your backpack?
No airline has a universal one-price baggage add-on. Prices vary by route, departure date, booking time, capacity, fare and channel; easyJet expressly says bag prices vary. Therefore a guide offering one “current guaranteed fee” for every flight would mislead you.
Here is a break-even calculation, using hypothetical checkout amounts solely to demonstrate the method:
Cost of keeping an oversized bag = sum of the genuine add-on prices for each flight leg that requires it.
Cost of getting a smaller bag = the new bag’s actual purchase price, less any value you receive from replacing another item (if relevant).
- Two legs at €24 extra each: €48 in add-ons versus a €35 smaller bag. The bag costs €13 less, if everything you need fits.
- One leg at €14 extra: paying once costs €31 less than a €45 replacement bag.
- Three return trips at €20 per leg: six add-ons total €120. A €55 smaller bag costs €65 less across those trips.
These are not observed offers, airline fee quotes or shopping recommendations. They simply show why a traveller who takes many budget trips may make a different choice from a person flying once. Your real checkout can reverse every example.
Three non-price factors matter. A rigid bag may offer better protection for camera equipment. A soft backpack can be easier on cobblestone streets and tight transport. Travelling for work with a laptop may change what you cannot leave behind. Our answer is not always “buy a new bag”: sometimes one paid overhead item, or packing less, is a better decision.
A real-world planning case: easyJet outbound, Ryanair return
Imagine a London–Milan trip (a hypothetical airline combination, not a current flight offer). The outbound easyJet free limit is 45 × 36 × 20 cm. A fully packed 44 × 34 × 20 cm backpack falls within those dimensions, subject to weight and other conditions.
Your return fare is basic Ryanair. Its free limit is 40 × 30 × 20 cm. The bag exceeds two dimensions. There is no reliable way to save it by saying that easyJet allowed it last week. Your options are to reduce the bag’s actual exterior size, buy an appropriate Ryanair baggage entitlement if available and economical, or choose a smaller compliant bag in advance.
Repeat the same exercise with Wizz Air in the return position: the common free bag target is also 40 × 30 × 20 cm, with the Wizz-specific 10 kg maximum.
The purchase lesson: it is the airline on the strictest leg that sets your cross-airline shopping requirement. Check the return and any separately ticketed connection before you choose a product.
How to inspect an advertised “Ryanair-approved” backpack
Ask five specific questions before clicking Buy:
- Are these outside dimensions or main-compartment dimensions? Exterior matters.
- Were they measured empty or fully packed? Fabric and pockets stretch.
- Are handles, wheels and bulging side pockets included? Especially important on mixed-airline trips.
- Can the retailer confirm the exact model and revision? Similar model names often have different external shapes.
- What is the return policy if the actual bag is larger? Keep the packaging until you have independently measured it.
A seller’s “airline approved” wording does not replace the airline’s own rules. Keep the listing and measure the delivered bag while it is still returnable. This guide compares allowances and hypothetical dimensions, not physically tested backpack models.
Packing enough without turning an underseat bag into a swollen cube
The easiest way to lose dimensional compliance is to plan a 24-litre trip using an abstract number and then force extra shoes, cables and toiletries into external pockets. Begin with needs instead: travel documents, necessary medication, one or two changes of clothing, a weather layer and device charger. Bulky winter shoes or a camera may change the feasibility of a two-night trip.
Pack once at home and remeasure after closure. If you are taking a power bank, follow the airline’s separate safety restrictions for battery watt-hours rather than assuming bag dimensions answer battery questions. See our power-bank flight rules guide, and for clothing choices our carry-on packing guide.
The 30-second decision
- Flying any combination of these three on basic allowances? Shop for or pack to 40 × 30 × 20 cm or smaller, and respect Wizz Air’s 10 kg weight limit.
- Flying easyJet only? You may use the larger 45 × 36 × 20 cm small-bag allowance within its conditions.
- Already own a bigger bag? Get your actual add-on quote for every flight and compare it with the cost of a smaller bag.
- Buying an overhead trolley? Check each carrier’s paid dimensions separately; they differ in depth.
- At the published maximum? Measure fully packed, not flat, and keep some margin if possible.
Official rules and review date
Checked October 2026: Ryanair bag policy, Wizz Air baggage allowance, easyJet cabin bags, easyJet fees. Always confirm exact fare and booking entitlements before travelling. No first-hand gate test, manufacturer measurement or guaranteed quote is claimed.