The hex key size depends on your disposal model, but 1/4 inch is the most common
Most garbage disposals use a 1/4 inch hex key (also called an Allen wrench) to turn the motor shaft and clear a jam. Some older or specialty models use 5/16 inch instead. The size is printed in your disposal's manual, and you can also find it by checking the manufacturer's website with your model number — it's usually on a label under the sink.
If you don't have the manual, a 1/4 inch hex key is your safest first guess. It fits the most common disposals made by InSinkErator, Waste King, and Badger. If it doesn't fit snugly into the socket at the bottom of the motor, stop and try 5/16 inch instead. Forcing the wrong size can strip the socket and make the problem worse.
Key Takeaways
- A 1/4 inch hex key works for the majority of garbage disposals, but your model number and manual will confirm the exact size.
- The socket you're turning is located at the bottom center of the motor housing, directly under the sink.
- Always turn the hex key slowly and gently — you're freeing a jam, not forcing the motor to spin.
- If the hex key doesn't fit snugly or the socket won't budge, stop and call a plumber rather than risk damaging the motor.
Where to find your disposal's hex key size
Look for a label or nameplate on the side or bottom of the disposal housing. It will list the brand, model number, and often the hex key size. InSinkErator and Waste King both print this information clearly on their units.
If the label is worn or missing, visit the manufacturer's website and search for your model number. Most companies post spec sheets that include the hex key size. You can also call the manufacturer's customer service line with your model number — they can tell you in seconds.
How to use the hex key safely
Before you touch anything, turn off the disposal and make sure the power switch is in the OFF position. Unplug the unit if you can reach the outlet, or flip the breaker that controls it. A disposal can start without warning if someone flips the switch while you're working.
Insert the hex key into the socket at the bottom center of the motor housing. Turn it slowly back and forth — a quarter turn in each direction — to loosen whatever is jamming the blades. You're not trying to spin the motor; you're just breaking the jam free. Once it moves, remove the hex key, plug the disposal back in, and run cold water while you turn it on to flush out the debris.
If the socket won't budge after a few gentle attempts, stop. Forcing it can crack the motor housing or strip the socket. Call a plumber at that point — the jam may be something that needs professional removal.
What to do if you don't have the right hex key
A hardware store or home center will have hex key sets that include 1/4 inch and 5/16 inch sizes. They cost between $5 and $15 for a full set. Buy a set rather than a single key — you'll have the right size on hand, and the extra keys are useful for other household items.
Do not use a screwdriver, pliers, or any other tool as a substitute. They won't fit properly, can slip and damage the socket, and may injure your hand if they slip out under pressure.
Common hex key sizes by disposal brand
| Brand | Most Common Size | Also Check For |
|---|---|---|
| InSinkErator | 1/4 inch | 5/16 inch (older models) |
| Waste King | 1/4 inch | 5/16 inch (commercial models) |
| Badger | 1/4 inch | 5/16 inch (heavy-duty models) |
| Moen | 1/4 inch | Check model label |
When to call a plumber instead
If the hex key doesn't fit the socket, or if the socket won't turn after gentle pressure, the jam may be lodged deeper in the unit or the motor itself may be damaged. Forcing it will only make the repair more expensive.
Also call a plumber if you've cleared the jam with the hex key but the disposal still won't run, makes a grinding noise, or leaks water. These are signs of internal damage that requires professional repair or replacement.
Frequently Asked Questions
Can I use an electric drill with the hex key to turn the motor?
No. A drill will spin the motor too fast and too hard, which can damage the blades, bearings, or motor windings. Always turn the hex key by hand, slowly and gently, using only your arm strength.
What if the hex key gets stuck in the socket?
Stop turning when ready and try to wiggle it free with gentle back-and-forth motion. If it won't come out, explore a penetrating oil like WD-40 around the socket, wait 10 minutes, and try again. If it's still stuck, call a plumber — forcing it out can break the key or damage the socket.
Do I need to remove the disposal to use the hex key?
No. The socket is accessible from underneath the sink while the disposal is mounted. You may need to remove the P-trap or move pipes slightly to reach it, but the disposal itself stays in place.
Is it normal for the socket to be hard to turn?
Yes, especially if the disposal has been jammed for a while. The jam creates friction. Turn gently and let the penetrating oil do the work — spray it around the socket, wait 15 minutes, and try again. Patience works better than force.