How to Find Wiper Blade Size: Length and Arm Type
How to find wiper blade size for your car: where the length is listed, how to measure each side, and how to identify the arm fitting so the new blade clips on.
Here is how to find wiper blade size in one paragraph. A wiper blade needs two things to be right: its length, which is set separately for each position (driver, passenger and rear), and its attachment, which must match the fitting on the end of your car's wiper arm. Get the length from your owner's manual, the marking on the old blade, or a tape measure along the old blade. Get the attachment type by looking at the end of the arm itself. A size chart gives you the first. Only your arm gives you the second.
That second part is where most wrong purchases happen. The sections below cover both, in the order to check them. The connector descriptions come from a wiper maker's published guide, and the regulatory detail from the US federal standard, both read on September 25, 2026.
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The two numbers that decide a wiper blade
Length. This is the number people mean by "wiper size". It is the length of the blade, and it is often different for each side of the windshield. A car that takes one length on the driver's side can take a different one on the passenger side, and the rear wiper, if there is one, is usually its own size again.
Attachment type. This is the shape of the fitting at the end of the wiper arm, where the blade clips on. A blade of the perfect length is useless if its connector does not suit your arm. Many wiper arms look alike from a distance and are quite different up close.
A lookup chart that lists "22 in and 18 in" has told you the lengths. It has not told you the fitting, and on some models more than one arm type was used across years or trims.
How to find wiper blade size for your car: the length
Work through these sources in order. Each one is more specific to your car than the one after it is to anyone's.
1. The owner's manual
Many owner's manuals list wiper blade lengths or a replacement part reference in the maintenance or specifications section. If you do not have yours, our list of where to get your owner's manual free, by manufacturer shows each maker's source.
2. The old blade
Blades are often marked with a length or a part number on the frame or the packaging label. A part number can be looked up on the blade maker's site. For one brand worked through in full, our Michelin wiper blades size chart lists each part number with its length. This only helps if the old blade was the correct size in the first place. A previous owner may have fitted whatever was on the shelf.
3. A tape measure
Lift the arm away from the glass and measure the old blade from end to end. Do it for each position separately, and write the numbers down with the position beside them. Measure the blade, not the arm. If the old blade is clearly too short (it leaves an unwiped strip at the edge of its sweep) or too long (it hits the other blade or the windshield trim), note that too, because it means the old blade is not your reference.
4. A maker's vehicle lookup
Wiper makers publish lookups by vehicle. TRICO's installation finder, for example, lets you search "by vehicle" (type, make, year and model) or "by arm type." Treat a lookup result as a strong starting point, then confirm it against sources 1 to 3. For one maker's full list of lengths, see our Rain-X wiper blades size chart. Our explainer on why two websites give your car two different numbers covers why lookups sometimes disagree.
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Reading your own arm: the common attachment types
Now the part a chart cannot do for you. Look at the end of the wiper arm where the blade connects. Champion's guide to windshield wiper connectors, published on DRiV's Parts Matter site, describes these common types:
| Connector | How the maker describes it | Size variants listed |
|---|---|---|
| J-hook | "The most common type of connector," with "a J or U-shaped hook at the end" | Short J hook, 7mm, 9x3, 9x4, 9x3 short, reverse 9x4 |
| Side pin | "A small pin on the wiper arm that fits into a hole on the wiper blade attachment" | 1/4", 19mm, 22mm, 3/16" |
| Bayonet | "A small indent on the top that fits in a hole to attach the blade assembly to the wiper arm" | 5mm, 7mm, 19mm, 22mm |
| Pinch tab | "A pair of pinch tabs that you simply press together to release the wiper blade" | Not listed |
| Pinch tab button | Like the pinch tab, with "an additional locking button hole" | Not listed |
| Saddle | "Mainly used on medium- and heavy-duty vehicles and RVs" | 1/2", narrow, wide |
The same guide also covers older styles found on vintage cars, such as the wrist action (flat hook), dead locker and saddle hook.
How to tell them apart in practice
- A curved hook at the end of the arm is a J-hook. Then check its size: the guide lists several J-hook sizes, so the hook's width matters.
- A straight arm end with a pin sticking out sideways is a side pin. Its diameter varies, so compare against the sizes listed.
- A flat arm end with a small hole or indent near the tip points to a bayonet style.
- A blade that releases when you squeeze two tabs together is a pinch tab arm. Check for a button hole to tell the two pinch tab versions apart.
Take a clear photo of the arm end from the side and from above before you shop. It is much easier to compare a photo against a package than to remember what you saw.
Be aware that naming is not fully consistent across the industry, and other sources sometimes use "bayonet" loosely. Go by what the fitting physically looks like and match it to the drawing on the blade package or the maker's arm-type search, not to a name alone.
Why the box shows three fittings and the chart shows one size
This is the common confusion: the chart says one length, but the blade package lists several arm types. There are two reasons.
- Many blades are built to fit more than one arm type. A package may list the connectors it suits, sometimes with adapters included. The length on the chart still applies. Your job is to confirm your arm is one of the listed connectors.
- The chart may cover more than one arm. A model can change arm type across model years or trims. If the chart does not say which arm your car has, you need to check. Our guides on how to tell what trim your car is and model year vs build date help you pin down which version you have.
If your arm type is not named on the package, choose a different blade rather than forcing a fit. A blade that is not properly locked can come off the arm, and a bare arm can scratch the glass.
Why the length matters more than it seems
It is tempting to fit a slightly longer blade for "more coverage". The wiping pattern was designed for specific lengths.
In the US, the federal standard for windshield wiping systems, FMVSS No. 104, requires each passenger car windshield wiping system to wipe set minimum percentages of three defined areas of the windshield, listed in its tables as 80, 94 and 99 percent for areas A, B and C. You can read it at 49 CFR 571.104 on Cornell Law School's Legal Information Institute (read September 25, 2026). The maker designs arm length, sweep angle and blade length together to meet that. Change the blade length and you change what gets wiped.
In practice:
- Too short leaves unwiped areas, sometimes in your line of sight.
- Too long can hit the other blade, the windshield trim, or the edge of the glass, and may not follow the curve of the windshield properly.
This is why a car often has different lengths on each side. The two blades sweep different areas, and each length was chosen for its own arm.
A quick checklist before you buy
- Note the length for the driver side, passenger side and rear separately.
- Confirm the lengths from the manual or old blades, not only from a website.
- Photograph each arm end and identify its connector type.
- Check the blade package lists your connector type for each blade you buy.
- After fitting, make sure each blade is locked onto the arm before you run the wipers.
If an arm is bent, loose on its pivot, or does not press the blade firmly against the glass, a new blade will not fix it. That is a job for a shop.
Frequently asked questions
How do I measure my wiper blade size?
Lift the arm away from the windshield and measure the old blade from end to end with a tape measure. Measure each position separately, because the driver and passenger sides are often different lengths.
Are wiper blades the same size on both sides?
Often not. Many cars use a different length on the driver's side and the passenger side, and the rear wiper is usually its own size. Check each position rather than buying a matching pair.
What is a J-hook wiper arm?
It is an arm that ends in a J or U-shaped hook, which Champion's connector guide calls the most common connector type. J-hooks come in several sizes, so check the hook size as well as the shape.
Will any wiper blade fit my car if the length is right?
No. The blade's connector must also suit your wiper arm's fitting. Check that the package lists your arm type before you buy.
Can I use a longer wiper blade for better coverage?
It is not a good idea. Blade length is designed with the arm and sweep pattern. A longer blade can hit the other blade or the trim and may not follow the glass properly. Use the length specified for your car.
