Bike Inner Tube Size Chart | Match Tube To Tire

Tube fit comes down to two numbers: tire width and ISO diameter, and both must match the size printed on your tire’s sidewall.

Buying a bike tube sounds simple until the labels start shouting 700x25c, 29 x 2.20, 47-622, and 26 x 1 3/8. One wheel can be described three ways, and tube boxes add even more ranges. Once you know which number is fixed and which number can flex, the choice gets much easier.

This chart is built to help you match a tube to the tire already on your bike. You’ll see how inch sizes, French sizes, and ISO numbers line up, where tube ranges make sense, and where riders get tripped up by labels that look close but do not fit the same rim.

How Tube Sizing Works On A Bike

An inner tube has to do two jobs. It must match the wheel diameter, and it must stretch across the tire width without being pushed too far. Get both right and installation feels normal. Miss either one and you’re more likely to deal with wrinkles, pinch flats, or a tube that fights you the whole way in.

The cleanest sizing system is ISO, also called ETRTO sizing. It uses width first, then rim diameter in millimeters. A tire marked 37-622 is about 37 mm wide and fits a 622 mm rim diameter. That last number is the one you treat like law. Width can span a range. Rim diameter cannot.

Start With The Number On The Tire

When you shop for a new tube, start with the tire sidewall, not the old tube. Tubes get swapped, mislabeled, or stretched into sizes that were never a great match. The tire tells you what the wheel is already using, so it is the safer place to read from.

Most tires show one or more of these markings:

• ISO / ETRTO: 28-622, 47-559, 54-584
• French style: 700x28c, 700x40c
• Inch style: 26 x 1.95, 27.5 x 2.25, 29 x 2.10

If you see more than one system on the sidewall, that’s normal. Brands print several versions to make the tire easier to shop across markets and bike types. The trick is to use the ISO diameter as your anchor, then choose a tube whose width range includes your tire.

Why One Tube Fits Several Sizes

Tube boxes often show a range such as 28/47-622 or 1.75-2.125. That does not mean the sizing is sloppy. Tubes are built to stretch, so one model can fit several nearby tire widths on the same rim diameter. A narrow road tube can cover a few millimeters. A mountain bike tube can span a chunk of width too.

Still, smaller ranges usually feel better in use. A tube that sits near the middle of its range is easier to seat, less likely to bunch up during install, and less likely to feel overworked. If your tire sits right on the edge of a tube’s range, it can work, though a closer match is nicer when you can get it.

What The Sidewall Numbers Are Telling You

Traditional sizes can fool you. Two tires may both say 26 inch and still fit different rims. A 700c road tire and a 29er mountain tire can share the same 622 rim diameter while looking nothing alike once width enters the picture. That’s why bike shops lean so hard on ISO sizing when labels get messy.

If you want a clean reference point, use the tire’s ISO line first. Both Continental’s ETRTO standards page and Park Tool’s fit standards put rim diameter at the center of the match. Once that number lines up, you can sort out width and valve style without guessing.

Bike Inner Tube Size Chart By Wheel Diameter

The chart below groups the sizes riders run into most often. Tube packaging varies a bit by brand, so treat the tube column as the label range you want to look for, not the only wording you may see in a shop or online listing.

Tire Size You May See	ISO Diameter	Tube Label To Look For
12 x 1.75–2.125	203	47/57-203
16 x 1.75–2.125	305	47/57-305
20 x 1.75–2.125	406	47/57-406
24 x 1.75–2.125	507	47/57-507
26 x 1.95–2.125	559	47/57-559
27.5 x 2.10–2.40	584	54/60-584
700 x 23–25c	622	18/25-622
700 x 28–35c	622	28/35-622
700 x 38–45c	622	37/45-622
29 x 2.10–2.40	622	54/60-622
27 x 1 1/4	630	32/37-630

When Similar Labels Are Not The Same

Some size pairs confuse riders again and again. The first is 700c and 29er. Both use a 622 rim diameter. The tube choice shifts with width, not with the name printed in big letters. A 700 x 28c road tire and a 29 x 2.25 trail tire do not use the same tube width, though the rim diameter line is the same.

The next pair is 27.5 and 650b. Those point to the same 584 rim diameter. Road, gravel, and mountain brands may label the tire one way or the other. If the width matches your tire and the diameter says 584, you are in the right part of the rack.

Then there’s old-school 26 inch sizing. This is where riders get burned. Modern mountain 26-inch tires usually use ISO 559. Older roadster and touring tires may use 590, 597, or other diameters hiding behind familiar inch labels. If your bike is older, the ISO number matters even more than usual.

Picking The Right Width Range

Width is where tube choice gets practical. Too narrow and the tube stretches thin. Too wide and it bunches during install, which makes pinches easier to cause with the tire lever or the bead. You want a tube range that covers your tire without forcing the tube to live at either extreme.

A good rule is to stay near the center of the printed range when you can. A tube marked 28/35-622 is a clean fit for a 30, 32, or 35 mm tire. It can still work at the edge of that range, though a more centered match usually feels better while mounting and while riding.

Your Tire Width	Tube Width Range That Fits Well	Range To Skip
23–25 mm	18/25	35/45
28–32 mm	25/32 or 28/35	18/25
35–43 mm	35/43 or 37/45	18/25
1.75–2.125 in	1.75–2.125	2.5–2.8
2.2–2.4 in	2.1–2.4	1.75–2.125
2.5–2.8 in	2.5–2.8	2.1–2.4

Valve Choice Still Matters

Tube size is only half the buy. Valve style has to match your rim hole, and valve length has to suit your wheel depth. Most road, gravel, and many tubeless-ready rims use Presta. Many kids, city, and older hybrid wheels use Schrader. Some city bikes still run Dunlop or Woods valves.

If your current tube works with your rim, copy that valve type unless you know the rim drilling can accept another one. Deep road rims add one more step: you may need a longer Presta valve so the pump head can reach it without a valve extender.

• Presta: slimmer valve, common on road and gravel wheels
• Schrader: car-style valve, common on many city, kids, and basic MTB wheels
• Dunlop/Woods: still seen on some city bikes and older utility bikes

Mistakes That Cause The Wrong Tube

Most bad tube buys come from a short list of habits:

• Matching only the big number. “700” or “26” alone is not enough.
• Ignoring the ISO diameter. This is the number that must line up.
• Buying a huge width range. A tube that spans too much can feel sloppy during install.
• Forgetting the valve. The size may be right while the valve makes the tube useless.
• Reading the old tube instead of the tire. The old tube may have been a compromise from day one.

If you’ve ever fought a tube that seemed to twist inside the tire or bulge under the bead, one of those mistakes was usually part of the story. Tube shopping gets a lot calmer once you read the tire first, match the ISO diameter, then narrow the width range and valve style.

A Simple Way To Buy The Right Tube Every Time

When you’re standing in a shop aisle or scrolling a product page, use this order. First, read the tire sidewall. Second, match the ISO diameter. Third, pick the width range that lands close to your tire rather than at the far edge. Last, copy the valve type and valve length your rim needs.

That short routine cuts through nearly all the noise around bike tube sizing. Once you start reading tubes this way, the labels stop feeling random. They turn into a plain fit check: same diameter, suitable width range, correct valve. Get those three right and you’re set.