The right size depends on your disposal model, but 1/8 inch and 3/16 inch are the most common
Most garbage disposals use a 1/8 inch or 3/16 inch Allen wrench to clear jams or remove the grinding chamber. The exact size varies by manufacturer — InSinkErator, Waste King, and Badger each design their own hex sockets. Before you buy a wrench, check your disposal's manual or look for a size marking stamped or printed near the hex opening at the bottom of the unit.
If you cannot find the manual, the safest approach is to buy a small set of Allen wrenches (also called hex keys) that includes sizes from 1/16 inch to 1/4 inch. A set costs $5 to $15 and covers most disposals you will encounter. Test-fit each size gently — the correct one will slide in smoothly without forcing.
Never force a wrench that does not fit. Forcing a too-small wrench can strip the hex socket, making future unjamming impossible without professional help. If no size in a standard set fits, your disposal may use a metric size (2 mm or 3 mm are common), which you can buy separately at any hardware store.
Key Takeaways
- Most disposals use either 1/8 inch or 3/16 inch Allen wrenches, but your manual or the unit itself will tell you the exact size.
- A small set of Allen wrenches costs under $15 and covers nearly all residential disposals.
- Test-fit gently and never force a wrench into the hex socket, because forcing can permanently damage it.
- If a standard set does not fit, your disposal likely uses a metric size like 2 mm or 3 mm.
How to find the size without a manual
Look at the bottom of your disposal unit. Most manufacturers stamp or print the wrench size directly on the housing near the hex opening. The marking might say "1/8"" or "3/16"" or show a metric equivalent. Shine a flashlight underneath if the marking is hard to read.
If there is no marking, check the nameplate on the side of the unit. It usually lists the model number. You can search that model number online with the word "manual" or "unjam" to find the correct size. Manufacturer websites (InSinkErator.com, WasteKing.com, and Badger.com are the three largest) have downloadable manuals searchable by model.
As a last resort, bring the model number to a hardware store and ask staff to test-fit sizes from a small set. They can tell you which one fits without forcing.
Why you need the exact size
A wrench that is too small will spin inside the hex socket without gripping. A wrench that is too large will not fit at all. Either way, you cannot turn the socket to free a jam or remove the chamber for cleaning.
More importantly, forcing a wrench that does not fit can strip the hex socket's edges. Once stripped, no wrench will grip it, and you will need a plumber to remove the chamber or replace the entire unit. Stripping is permanent and expensive to fix, so testing the fit first is worth the two minutes it takes.
Standard sizes across common brands
| Brand | Common Models | Typical Wrench Size |
|---|---|---|
| InSinkErator | Evolution, Badger, Compact | 1/8 inch or 3/16 inch |
| Waste King | L-8000, L-2600 | 1/8 inch |
| Badger | Badger 5, Badger 1 | 3/16 inch |
| Moen | Host series | 1/8 inch or 3/16 inch |
This table shows the most common sizes, but always verify with your manual or the unit itself. Manufacturers sometimes change socket sizes between model generations, so a newer Badger might use 1/8 inch while an older one uses 3/16 inch.
What to do if you cannot find the right size
If you have tested every size in a standard set and none fit, your disposal likely uses a metric size. Metric Allen wrenches are sold separately and come in sizes like 2 mm, 2.5 mm, 3 mm, and 4 mm. A metric set costs $5 to $10 and is worth buying if you plan to own the disposal long-term.
If metric sizes also do not work, the hex socket may be damaged or your disposal may use a different tool altogether (some older models use a slot-head wrench or a special key). At that point, call a plumber. Trying to force the wrong tool risks breaking the socket further and making the jam worse.
How to use the Allen wrench safely
Turn off the disposal and make sure it is unplugged before inserting the wrench. Insert the wrench into the hex socket at the bottom of the unit and turn it slowly by hand. You are trying to rotate the grinding chamber to dislodge whatever is stuck, not to force it.
If the chamber does not turn after a few gentle attempts, stop. Forcing it can break the motor or jam the mechanism further. Remove the wrench, plug the disposal back in, and run cold water for 30 seconds to see if the jam has loosened. If it has not, call a plumber rather than continuing to force it.
Once the chamber turns freely, unplug the disposal again and use tongs or pliers to remove any visible debris from the chamber. Do not put your hand inside. Plug it back in, turn it on briefly with cold water running, and listen for normal grinding sounds.
When to call a plumber instead
If the wrench fits but the chamber will not turn, or if it turns but the disposal still will not grind after you remove the jam, the motor or internal gears may be damaged. A plumber can diagnose the problem and repair or replace the unit.
You should also call a plumber if you do not feel confident using the wrench, if the hex socket is already stripped or damaged, or if the jam involves something that should never have gone down the drain (like glass, metal, or bone). Trying to clear these yourself can damage the disposal beyond repair.
Frequently Asked Questions
Can I use a different tool if I do not have the right Allen wrench?
No. Using a screwdriver, pliers, or any other tool will strip or damage the hex socket. The socket is designed for a specific wrench size, and nothing else will grip it safely. Buy the correct size — it costs less than $2 if you buy a single wrench, or under $15 for a set.
Is it normal for the chamber to be hard to turn?
Slight resistance is normal, especially if the disposal has not been used in a while. Turn slowly and steadily. If it feels completely stuck or you have to strain hard, stop and do not force it. The jam may be too severe for a wrench to clear safely.
What if the wrench spins but nothing happens?
The wrench may be too small and spinning inside the socket without gripping. Try the next size up. If you have already tested all sizes in your set, the socket may be stripped, or you may need a metric size. A plumber can tell you for certain.
Do I need to remove the entire disposal to use the wrench?
No. The hex socket is accessible from underneath while the disposal is mounted under the sink. You do not need to remove it. Just unplug it, insert the wrench from below, and turn gently.
Can I use an electric drill with an Allen wrench bit?
No. Always turn by hand. An electric drill applies too much force and can break the motor, strip the socket, or cause the chamber to spin so fast that it damages itself or throws debris. Hand-turning gives you control and lets you feel when something is wrong.