45 x 36 x 20 cm equals about 17.7 x 14.2 x 7.9 inches, a common under-seat cabin size.
Travel sites and airline pages quote dimensions in centimeters, inches, or both. If your tag reads 45 × 36 × 20 cm, here’s the clean conversion to inches and what that means for packing, sizers, and real-world fit under the seat. You’ll also see which airlines match this size, plus a quick method to convert any tape-measure reading without a calculator.
45 X 36 X 20 Cm Bag Size In Inches: Clean Conversion
The exact math uses the fixed relationship 1 inch = 2.54 cm. That’s the legal definition used in standards work and technical labeling. Using that constant, the size converts to about 17.7 × 14.2 × 7.9 inches. For travel, rounding to one decimal (or the nearest 1/8 inch) keeps the numbers readable on tags and sizers.
Quick Conversion & Fit Reference
| Item | Metric (cm) | Inches (decimal / nearest 1/8″) |
|---|---|---|
| Length | 45 | 17.7 / 17 3/4″ |
| Width | 36 | 14.2 / 14 1/8″ |
| Depth | 20 | 7.9 / 7 7/8″ |
| Linear Sum | 101 | 39.8 / 39 3/4″ |
| Box Volume (est.) | 32.4 L | ≈ 1,979 in³ |
| Laptop Sleeve Guide | Up to ~40 cm | Up to ~15.7″ |
| Typical Uses | Under-seat | Backpack, tote, slim duffel |
Why This Size Shows Up Everywhere
Many European carriers list an under-seat allowance close to this footprint. One well-known match is the easyJet under-seat size of 45 × 36 × 20 cm (handles and wheels included). If your bag fits these centimeters, it fits their sizer. A few airlines set smaller personal-item limits, so always compare the tag on your bag with the chart later in this guide.
How We Convert, Round, And Label Bag Sizes
The conversion uses a constant adopted across standards bodies: divide centimeters by 2.54 to get inches. To keep labels tidy, round to one decimal for tags and use a fraction like 1/8″ when you’re checking against metal sizers at the gate. Precision beyond that rarely changes a fit decision, since seams, corner caps, and soft shells can add a few millimeters.
Step-By-Step Method
- Write each side in centimeters: 45, 36, 20.
- Divide each by 2.54.
- Round to one decimal for a quick read. If you prefer a tape-measure feel, convert the decimal to the nearest 1/8″.
That’s how we reached 17.7 × 14.2 × 7.9 inches. If you want the fraction set, it’s 17 3/4″ × 14 1/8″ × 7 7/8″.
When Rounding Helps—And When It Doesn’t
Soft bags compress at the corners, so a rounded 17.7″ side won’t cause trouble in a sizer that’s a hair tighter. Hard-shell cases don’t give as much, and wheel housings can push depth over the line. If your case is rigid, measure the longest point, not just the shell panel.
About The Constant
The inch-to-centimeter relationship is fixed by standards: 1 in = 2.54 cm. You’ll see this in conversion guidance used across labs and industry. A clear reference is NIST’s appendix on conversion factors, which explains that inch-based units are defined from SI units; see the NIST conversion factor note that calls 2.54 cm per inch exact.
Travel Rules For 45 X 36 X 20 Cm Bag Size In Inches
This footprint aims at the “under-seat” tier. That tier usually rides free and avoids overhead-bin scrambles. Airlines enforce shapes a bit differently, so compare your tag with each carrier’s posted limits before you pack.
What Fits Inside A 45 × 36 × 20 Cm Bag
- 13–15″ laptop in a sleeve, plus charger and mouse.
- Noise-canceling headphones or earbuds case.
- Light sweater or scarf rolled tight.
- Toiletry pouch within liquids rules.
- Compact camera or mirrorless body with a small lens.
- Passport, wallet, phone, power bank, cable kit.
If you carry camera cubes, keep the cube height under 8″ so the zipper closes without bulging past 20 cm.
Packing Tips That Save Space
- Stand the heaviest items near the base so the bag sits flat under the seat.
- Use flat pouches for tech and documents; stacks waste the 20 cm depth.
- Choose a slim bottle or foldable pouch; round bottles eat width.
- Pick a soft case if you’re close to the limit; it flexes into sizers.
- Measure with wheels and handles included, since many carriers count them.
Does Linear Inches Matter?
Some carriers list a single “linear” number (length + width + depth). For this bag, the linear total is about 39.8″. That’s handy for shipping or checked-bag rules. For personal items, airlines usually list three separate sides, so go by the side-by-side numbers first.
Common Airline Limits Near This Size
Policies change, but the trend is simple: an under-seat personal item shows a tight footprint, and a larger overhead bag costs extra or requires a fare bundle. The rows below show current published under-seat dimensions from a few well-known carriers that travelers mix up with 45 × 36 × 20 cm. Always check your exact flight after booking.
Under-Seat Personal Item Allowances
| Airline | Free Under-Seat Bag (cm) | Free Under-Seat Bag (in) |
|---|---|---|
| easyJet | 45 × 36 × 20 | 17.7 × 14.2 × 7.9 |
| British Airways (small item) | 40 × 30 × 15 | 15.7 × 11.8 × 5.9 |
| Ryanair (small bag) | 40 × 30 × 20 | 15.7 × 11.8 × 7.9 |
Notes On The Chart
For easyJet, the under-seat allowance listed above comes straight from their policy page. British Airways lists a smaller “small item” in the seat area and a larger cabin bag for the overheads; the under-seat line is the one that maps to a personal item. Ryanair’s small bag sits close on length and width, with the same 20 cm depth. If your trip mixes carriers, plan to the smallest set of numbers and you’ll breeze through sizers.
How To Check Your Bag At Home
Measure The Longest Points
Place the bag on a flat surface. Measure shell to shell including corner caps, then re-measure across wheels and handles. Use the larger reading for each side.
Do A Simple Sizer Mock-Up
Cut painter’s tape to a rectangle on the floor at 45 × 36 cm. Stand the bag in the rectangle and check bulges. Set a book at 20 cm height to mimic a sizer’s depth bar. If it clears without force, you’re in range.
Buying A Bag Built To 45 × 36 × 20 Cm
Look for product pages that list dimensions including wheels and handles. Many tags list the shell only; that can put you a centimeter over once the puller and feet are counted. For backpacks and totes, look at the depth number and the shape of the corners—tapered tops slide under seats better than boxy tops.
Soft Vs. Hard Shell
Soft shells shave off a few millimeters in a tight sizer and let you pinch the top under the seat bar. Hard shells protect gear and keep structure, but the 20 cm depth limit becomes strict once the wheels are included. If you carry a laptop and camera, a soft daypack or slim duffel often wins for this footprint.
Best Uses For This Footprint
- Weekend hop with a small packing cube set.
- Work trips where the laptop and one change of clothes share space.
- Tech carry with camera, headphones, and cords in flat pouches.
Fast Math: Convert Any Bag From Cm To Inches
Use this pocket rule: divide by 2.54. If mental math helps, 2.5 is close enough for a quick check, then refine with 2.54 when you’re near a limit. The standard behind that number is fixed, and it’s the same one used on engineering drawings and labeling rules.
Mini Worksheet You Can Save
- Write the three sides in cm.
- Divide each by 2.54 and round to one decimal.
- Sum the three inch values if a policy lists linear inches.
That’s all you need to confirm a tag like 45 × 36 × 20 cm bag size in inches before you head to the airport. If you’re shopping online, you can paste the numbers into your phone’s calculator in seconds.
FAQ-Free Bottom Line
Here’s the plain answer people search for: the 45 × 36 × 20 cm bag size in inches is about 17.7 × 14.2 × 7.9. That footprint lines up with common under-seat rules, keeps a laptop and daily carry tidy, and avoids overhead-bin battles on airlines that enforce one free personal item. If you stick with the numbers above and measure the longest points—wheels and handles included—you’ll be set.