A double ear clamp size chart lists each clamp by its open and closed inside diameter, for example 22.5 to 27 mm (0.886 to 1.063 in). To pick a size, measure the hose outside diameter where the clamp will sit, after the hose is pushed onto the barb. Choose the clamp whose range puts that number a little above the middle.
The reason is arithmetic. The two ears of a 2-ear clamp can only absorb a fixed length of band, and that length sets how far the clamp can shrink. Work it out and you can check on paper whether a clamp will grip your hose before you crimp one.
If the clamp type itself is still open, read what a double ear clamp is and how to choose a double ear clamp first. This page deals only with size.
Double ear clamp size chart in mm and inches
Double ear clamps are catalogued in metric. The usual name for a size joins its smallest and largest diameter, so “2327” means a clamp that works from 22.5 mm to 27 mm. Inch catalogues usually convert those ranges and may add a rounded “nominal” fraction. Dixon’s pinch-on double ear clamps, for example, use the same four-digit codes and list 2023 as 0.748 to 0.906 in with a 7/8 in nominal size.
The chart below is a representative selection, not a full catalogue. The ranges come from the Oetiker 2-ear clamp technical data sheet for product groups 101 and 151, which covers 3.1 to 46 mm. The right-hand column gives the nearest size in the Mikalor two ear clip range. The two makers split the scale slightly differently. Inch values are our conversions (mm ÷ 25.4).
| Ref. (Oetiker style) | Range, mm | Range, inch | Span, mm | Nearest Mikalor range, mm |
|---|---|---|---|---|
| 0305 | 3.4 – 5.0 | 0.134 – 0.197 | 1.6 | none (starts at 5) |
| 0507 | 5.0 – 7.0 | 0.197 – 0.276 | 2.0 | 5 – 7 |
| 0709 | 7.0 – 9.0 | 0.276 – 0.354 | 2.0 | 7 – 9 |
| 0811 | 8.1 – 11.0 | 0.319 – 0.433 | 2.9 | 9 – 11 |
| 1113 | 10.8 – 13.0 | 0.425 – 0.512 | 2.2 | 11 – 13 |
| 1315 | 12.5 – 15.0 | 0.492 – 0.591 | 2.5 | 13 – 15 |
| 1517 | 14.0 – 17.0 | 0.551 – 0.669 | 3.0 | 14 – 17 |
| 1518 | 15.0 – 18.0 | 0.591 – 0.709 | 3.0 | 15 – 18 |
| 1619 | 16.0 – 19.0 | 0.630 – 0.748 | 3.0 | 15 – 18 / 17 – 20 |
| 1720 | 16.2 – 20.0 | 0.638 – 0.787 | 3.8 | 17 – 20 |
| 2023 | 19.0 – 23.0 | 0.748 – 0.906 | 4.0 | 20 – 23 |
| 2225 | 21.0 – 25.0 | 0.827 – 0.984 | 4.0 | 22 – 25 |
| 2327 | 22.5 – 27.0 | 0.886 – 1.063 | 4.5 | 23 – 27 |
| 2731 | 26.3 – 31.0 | 1.035 – 1.220 | 4.7 | 28 – 31 |
| 3134 | 29.3 – 34.0 | 1.154 – 1.339 | 4.7 | 31 – 34 |
| 3437 | 32.0 – 37.0 | 1.260 – 1.457 | 5.0 | 34 – 37 |
| 3740 | 35.0 – 40.0 | 1.378 – 1.575 | 5.0 | 37 – 40 |
| 4346 | 40.6 – 46.0 | 1.598 – 1.811 | 5.4 | 43 – 46 |
Two things stand out. The span (largest minus smallest diameter) is only 2 to 5.4 mm, far narrower than a worm gear clamp. And neighbouring sizes overlap, so most hose diameters fit two or three clamps; the section on choosing between sizes uses that overlap.
Material limits availability. Oetiker’s stainless group (151, 1.4307) mirrors its zinc-plated group (101) for most sizes, but 1619 is listed zinc-plated only. Mikalor lists W1 zinc-plated sizes to 46 mm but W4 (304) only to 25 mm. Confirm your size exists in stainless before designing around it. Our post on 304 vs 316 double ear clamps covers the grade question itself.
How the two ears set the range: take-up arithmetic
An ear clamp shrinks in one way only: each ear, a raised loop in the band, is squeezed flat, which removes band length from the loop around the hose. Once both ears are flat, the clamp cannot shrink further. That is why the catalogue minimum is a hard stop.
Circumference first, diameter second
The band works in circumference; the chart is printed in diameter. Circumference equals π times diameter. If a clamp’s diameter shrinks by ΔD, the band has lost π × ΔD of working length. On a 2327 clamp the span is 4.5 mm, so the two ears together must absorb about 3.1416 × 4.5 = 14.1 mm of band. That is roughly 7 mm per ear.
Oetiker publishes a related rule for its single ear clamps. Their data sheet gives the maximum diameter reduction as the ear width divided by π. So a fully closed ear removes roughly its own width from the circumference. The 2-ear sheet publishes no ear widths, so extending the rule to two ears is our approximation:
- Approximate rule (our extension, not a maker figure): maximum diameter reduction ≈ (width of ear 1 + width of ear 2) ÷ π.
- Turned around: the combined ear width a size needs ≈ π × (max diameter − min diameter).
- Reality check: real ears never close to zero gap, the band stretches a little under load, and the first ear may spring back slightly when the second is closed. Treat the result as a ceiling, not a promise.
Here is the same arithmetic applied to the double ear clamp size chart above (calculated, not published values):
| Size | Diameter span, mm | Band length absorbed (π × span), mm | Approx. per ear, mm | Same span, inch |
|---|---|---|---|---|
| 0709 | 2.0 | 6.3 | 3.1 | 0.079 |
| 1315 | 2.5 | 7.9 | 3.9 | 0.098 |
| 1720 | 3.8 | 11.9 | 6.0 | 0.150 |
| 2023 | 4.0 | 12.6 | 6.3 | 0.157 |
| 2327 | 4.5 | 14.1 | 7.1 | 0.177 |
| 3134 | 4.7 | 14.8 | 7.4 | 0.185 |
| 4346 | 5.4 | 17.0 | 8.5 | 0.213 |
The buyer’s lesson: more range needs bigger ears, and bigger ears stand taller. Going from 2023 to 2327 adds only half a millimetre of span. If your hose ODs vary by 5 mm or more batch to batch, an ear clamp is the wrong tool and a screw clamp is the better fit.
Will the closed diameter compress your hose enough?
Fitting inside the range is not the same as sealing. What matters is how hard the band squeezes the hose wall against the barb, and that depends on wall thickness.
A widely used method, set out in this Oetiker ear clamp selection guide published by Qosina, works in three steps:
- Hose OD on the shaft = barb shaft diameter + 2 × hose wall thickness. This is where the clamp will actually sit.
- Compression ceiling = (hose OD on shaft − clamp minimum diameter) ÷ (2 × wall thickness), as a percentage. This is the most the clamp could squeeze the wall if both ears closed completely.
- Position in range: the hose OD on the shaft should sit slightly above the middle of the clamp’s range.
The same guide suggests compression targets for tubing: roughly 15 to 20 percent for soft silicone, 20 to 30 percent for silicone and TPE around 50 to 60 Shore A, and 25 to 30 percent for braided tubing. It adds that testing finds the best figure. We found no verified figure for reinforced rubber hose, so treat anything outside roughly 15 to 40 percent as a warning sign (our rule of thumb, not a published limit).
Reading the ceiling the right way
Ear clamps are closed to a set pincer force, not a set gap. The ears stop where hose resistance balances that force, and in a correctly sized clamp they stop almost closed, as Oetiker’s installation note and the Wikipedia entry on hose clamps both say. So:
- Ceiling too low (under about 15 percent): both ears close completely before the wall is squeezed enough. Dixon’s installation procedure treats two fully closed ears as a sign the clamp is too large.
- Ceiling sensible (about 20 to 40 percent): the ears stop with a small gap, the hose carries the load and the clamp keeps some spring.
- Ceiling very high (50 percent or more): the ears stay visibly open, and pressing harder risks shearing the band. The clamp is probably a size too small for that wall.
How to measure for a double ear clamp
Our general guide on how to measure hose clamp size covers calipers, pi tapes and common errors. Here is what differs for ear clamps, where a 1 mm error can mean the wrong size.
Measure the hose on the fitting, not off it
A hose stretched over a barb grows in OD. Measure with the hose fully seated, where the band will sit: on the shaft behind the last ridge, not on the ridge. Take two caliper readings at 90 degrees (coiled hose goes oval) and average them, to 0.1 mm.
When you can only measure parts separately
On a design job, calculate instead. Measure the barb shaft and the largest ridge diameter; take wall thickness as half of (hose OD − ID). Then:
- Hose OD on shaft = shaft diameter + 2 × wall. This is the number you size the clamp to.
- Hose OD over the ridge = ridge diameter + 2 × wall. This is the largest diameter the open clamp must slide over if you fit it after the hose goes on.
The result runs slightly high because the wall thins as it stretches, so check one sample assembly if you can.
Check the open diameter against the ridge
An ear clamp cannot be opened up; its largest diameter is fixed. Dixon’s pinch-on clamp installation procedure makes the point plainly: the clamp has to slide over the hose OD after the stem is inserted. If the clamp maximum is below the hose OD over the ridge, either slip the clamp on before the hose goes onto the fitting, or move up a size. On a line, that changes the build sequence.
Note the wall and the hose type
Record wall thickness and hose type (soft PVC, silicone, rubber, reinforced). Two hoses with the same OD but 2 mm and 4 mm walls give very different ceilings with the same clamp.
Why a crimped clamp can’t be measured
Measuring the old clamp and ordering the same does not work with ear clamps:
- The diameter you see is a result, not a size. It shows where hose resistance stopped the ears, not the clamp’s range.
- The band is no longer round. It flattens beside each ear, so readings vary with angle.
- The ears are permanently deformed. It has to be cut off, and a cut band tells you nothing.
- Nobody knows how hard it was crimped. One ear may be shut and the other half shut.
A stamped size code on the band, if readable, is the best clue. Otherwise remove the clamp, leave the hose on the fitting, measure and size from scratch.
Worked double ear clamp sizing examples
These four jobs show the double ear clamp size chart in use. Barb and hose dimensions are illustrative, not from a specific product; measure your own. Ranges come from the chart; the ceiling uses the formula above.
Garden hose on a 5/8 in barb
Illustrative figures: barb shaft 15.5 mm, ridge 17.0 mm, rubber hose wall 3.5 mm. Hose OD on the shaft works out at 22.5 mm (0.886 in), and over the ridge it is 24.0 mm. The 2327 is out: 22.5 mm is its minimum, so the ears would bottom out. The 2225 has a midpoint of 23 mm and a ceiling of about 21 percent, and its 25 mm open size clears the ridge. The 2023 gives a ceiling near 50 percent but opens only to 23 mm, so it must be pre-placed. For a hand repair, use 2225; on a line that pre-places clamps, 2023 grips harder. Our guide to hose clamps for garden hoses and irrigation compares other clamps for this job.
Sprayer line, 3/8 in ID PVC
Illustrative figures: barb shaft 9.5 mm, ridge 11.0 mm, reinforced PVC wall 3.0 mm. Hose OD on the shaft is 15.5 mm (0.610 in), and over the ridge it is 17.0 mm. The 1517 sits exactly at its midpoint, with a ceiling of 25 percent, but it only opens to 17 mm. so slide it on first. The 1518 clears the ridge but its ceiling is about 8 percent, so it would close fully and underclamp. Choose 1517. Sprayers see pressure spikes when nozzles shut; Mikalor lists a pressure limit per size, falling as diameter rises.
Pond pump outlet, 1 in flexible PVC
Illustrative figures: barb shaft 25.0 mm, ridge 27.0 mm, wall 4.0 mm. Hose OD on the shaft is 33.0 mm (1.299 in), and over the ridge it is 35.0 mm. The 3437 (32 to 37 mm) clears everything but gives a ceiling of only about 12 percent, so its ears would probably close completely. The 3134 (29.3 to 34 mm) puts 33.0 mm above its midpoint of 31.65 mm. Its ceiling near 46 percent means the ears stop short of closed, which is acceptable on soft, low-pressure pond hose. Pre-place it (it opens to 34 mm, under the 35 mm ridge). A screw clamp is often the easier answer here; see the alternatives below.
Compressor air hose, 3/8 in ID rubber
Illustrative figures: barb shaft 10.0 mm, ridge 11.5 mm, wall 3.8 mm. Hose OD on the shaft is 17.6 mm (0.693 in), and over the ridge it is 19.1 mm. The 1619 (16 to 19 mm) has a midpoint of 17.5 mm, a ceiling of about 21 percent and an open size just under the ridge. That is the textbook fit, pre-placed. But Oetiker lists 1619 in zinc-plated steel only. If you need stainless, the 1720 (ceiling about 18 percent, slides on afterwards) is the fallback; inspect it for fully closed ears.
| Job (illustrative) | Hose OD on shaft | OD over ridge | First choice | Ceiling | Fit sequence |
|---|---|---|---|---|---|
| Garden hose, 5/8 in barb | 22.5 mm / 0.886 in | 24.0 mm | 2225 (21 – 25) | ≈21% | After hose is on |
| Sprayer, 3/8 in PVC | 15.5 mm / 0.610 in | 17.0 mm | 1517 (14 – 17) | ≈25% | Pre-place |
| Pond pump, 1 in PVC | 33.0 mm / 1.299 in | 35.0 mm | 3134 (29.3 – 34) | ≈46% | Pre-place |
| Air hose, 3/8 in rubber | 17.6 mm / 0.693 in | 19.1 mm | 1619 (16 – 19) | ≈21% | Pre-place |
Choosing between two double ear clamp sizes
Because neighbouring sizes overlap, most hoses could take two or three clamps. These rules settle it, in order of priority:
- Rule out any size where your OD is within about 0.5 mm of the minimum. The ears will close fully before the hose is squeezed. That half millimetre is our working margin, not a catalogue figure.
- Of what remains, prefer the size whose midpoint sits just below your OD. That leaves the ears room to close on the hose.
- Check the ceiling. If it is below about 15 percent, go down a size. If it is above about 50 percent on a thick or hard wall, go up one.
- Check the open size against the ridge. If the smaller clamp cannot slide over, either change the build sequence or take the larger size and accept a lower ceiling.
- Check availability in your material. Some sizes come only in zinc-plated steel, and some stainless ranges stop early.
- Check the maker’s pressure figure for the chosen size if the line runs above low pressure.
Hose hardness tilts the choice. Soft PVC and silicone tolerate the smaller size with a higher ceiling; hard reinforced rubber may leave its ears wide open, so aim for a ceiling in the 20s.
If one brand’s split leaves you on a boundary, check the other brand’s split in the first table before settling.
Inspecting the result
Dixon’s field check: if both ears close completely, fit the next smaller size; a first ear that opens slightly after the second is crimped is acceptable. Also look for cracks at the ear bends and hose bulging past the band edges, and stagger the ears if two clamps share a barb.
Pincers and crimping, briefly
Use pincers made for ear clamps, never side cutters or pliers, which nick and unevenly close the ear. Oetiker’s data sheet lists hand, pneumatic and cordless tools up to 20 mm but only powered tools for 22 to 46 mm. Close the first ear, then the second, then recheck the first; Oetiker notes it may need a second crimp.
Sizing a re-adjustable alternative from OneTouch
OneTouch Exim does not stock double ear clamps, or any ear clamp. We supply worm gear, constant torque, lined, T-bolt and V-band clamps. If ear clamps are hard to source, or your hose tolerance exceeds their few millimetres, a small worm gear clamp is the usual swap: a wider range per size, retightenable, removable without cutting.
The trade-offs: a taller housing, no tamper evidence, and on soft hose a perforated band can bite through its slots (the lined version prevents that). Map your range below, then see the perforated worm gear clamp category.
| If your hose OD on the shaft is | Double ear sizes that cover it | OneTouch alternative | OTE range |
|---|---|---|---|
| 6 – 15 mm (0.24 – 0.59 in) | 0507 to 1315 | 4SS0004 all-stainless mini | 0.22 – 0.63 in (5.6 – 16.0 mm) |
| 12 – 19 mm (0.47 – 0.75 in) | 1113 to 1720 | 4SS0006 all-stainless mini | 0.44 – 0.78 in (11.2 – 19.8 mm) |
| 14 – 22 mm (0.55 – 0.87 in) | 1315 to 2023 | 4SS0008 all-stainless | 0.50 – 0.91 in (13 – 23 mm) |
| 16 – 26 mm (0.63 – 1.02 in) | 1518 to 2327 | 4SS0010 all-stainless | 0.56 – 1.06 in (14.2 – 26.9 mm) |
| 22 – 37 mm, soft hose (0.87 – 1.46 in) | 2225 to 3437 | 4CL9416 lined, all-stainless | 0.81 – 1.50 in (21 – 38 mm) |
Per the product pages, the 4SS minis run a 5/16 in band (1/4 in hex) and the 4SS0008/0010 a 1/2 in band (5/16 in hex); every 4SS part is 301 stainless with a 410 screw, not 316. For the worked examples: sprayer and air hose fit the 4SS0008, the garden hose the 4SS0010, and the pond hose the lined 4CL9416.
If you have an ear clamp part number from Oetiker, Mikalor, Dixon or a private label, our clamp cross-reference lists the OneTouch screw clamp sizes that cover the same diameters.
Double ear clamp size questions buyers ask
Is a double ear clamp sized by hose ID or hose OD?
By outside diameter, measured where the clamp sits with the hose on the fitting. The ID matters only because it and the barb set that stretched OD.
What does a code like 1720 or 2327 mean on a double ear clamp size chart?
It is shorthand for the clamping range in millimetres: 1720 covers about 16.2 to 20 mm and 2327 covers 22.5 to 27 mm. The digits are not always exact, so read the range itself.
Can I use a bigger double ear clamp and just crimp harder?
No. A clamp can only shrink by the band its two ears can absorb. Once both ears are flat, extra force does nothing except risk cracking the band. If both ears close fully on your hose, the clamp is too large; fit the next smaller size.
How do I convert a double ear clamp size from mm to inches?
Divide each end of the range by 25.4. A 19 to 23 mm clamp becomes 0.748 to 0.906 in. Keep three decimals: a span may be only 0.08 in, and a fraction like 7/8 in hides where your hose sits.
Do stainless and zinc-plated double ear clamps of the same size have the same range?
Usually, but not always. In Oetiker’s sheet a few stainless sizes start 0.1 mm higher than the zinc-plated equivalent, and some sizes are only listed in one material. Mikalor’s published stainless list stops at 25 mm. Check the exact part, not just the size code.
Why does my double ear clamp leak even though it is in range?
Usually the hose OD sits too close to the clamp minimum, the ears were crimped unevenly, or the clamp sits on the ridge instead of behind it. Re-measure and recheck the ceiling first.
Send us the barb and hose numbers
Switching to a screw clamp you can retighten? Send us the hose OD on the shaft, wall thickness and quantity, and we will name the OneTouch size or tell you plainly if an ear clamp remains the better part. Start with the cross-reference table if you have a part number, or send the measurements through our contact and quote page. For other clamp families, the mm and inch size hub is the place to start.