An adjustable wrench is a hand tool used to loosen or tighten nuts and bolts with flat sides. It has one fixed jaw and one movable jaw, so you can adjust the opening to fit different fastener sizes.
Many people call it a Crescent wrench, but Crescent is a brand name. The generic name is adjustable wrench or adjustable spanner.
How an Adjustable Wrench Works
An adjustable wrench has a small worm gear near the head. When you turn the gear with your thumb, the lower jaw moves open or closed.
The main parts are:
- Fixed jaw — the stationary side of the wrench head
- Movable jaw — adjusts to fit the nut or bolt
- Worm gear — the thumbwheel that controls jaw size
- Handle — gives leverage for turning
The goal is to make the jaws fit tightly against the flat sides of the nut or fitting. A loose wrench can slip and round off the corners.
What an Adjustable Wrench Is Used For
An adjustable wrench is useful because one tool can fit many sizes of nuts and bolts.
Common homeowner uses include:
- Tightening furniture bolts
- Working on appliance leveling feet
- Loosening supply line nuts
- Holding or turning shutoff valve packing nuts
- Assembling fixtures or hardware
- Light plumbing repairs
- Tightening outdoor hose bib packing nuts
- General mechanical repairs around the house
It is not the perfect tool for every job, but it is one of the first wrenches most homeowners should own.
How to Choose an Adjustable Wrench
For most homeowners
Use an 8-inch or 10-inch adjustable wrench. This is the best size range for general home repairs.
For tight spaces
Use a 6-inch adjustable wrench. It is easier to fit under sinks, behind toilets, inside cabinets, or around small appliance connections.
For larger plumbing or outdoor work
Use a 12-inch adjustable wrench. The longer handle gives more leverage and the jaw opens wider.
For better grip
Look for:
- A jaw that does not wobble much
- Clear size markings
- A smooth adjustment wheel
- A comfortable handle
- A wide jaw opening if you do plumbing work
For nicer fixtures
Use a high-quality wrench with a tight jaw fit. Cheaper adjustable wrenches can have more jaw play, which makes slipping and rounding more likely.
Adjustable Wrench vs Tongue-and-Groove Pliers vs Pipe Wrench
| Tool | Best For | Avoid Using It On |
|---|---|---|
| Adjustable wrench | Nuts and bolts with flat sides | Round pipe |
| Tongue-and-groove pliers | Large or irregular plumbing fittings | Polished finishes without protection |
| Pipe wrench | Rough steel or iron pipe | Chrome, brass, copper, plastic, or decorative parts |
If the part has flat sides, start with an adjustable wrench. If it is round, choose a different tool.
How to Use an Adjustable Wrench
Open the jaws Turn the worm gear until the jaws fit around the nut or fitting.
Tighten the jaw Snug the movable jaw against the flat side of the nut. There should be very little wiggle.
Keep the wrench square The jaws should sit flat against the sides of the fastener.
Pull steadily Use controlled pressure. Do not jerk the tool or use a pipe as a handle extension.
Re-tighten as needed The jaw can loosen while you work. Recheck the fit often.
Common Mistakes
Leaving the jaw loose
This is the fastest way to round off a nut.Using it on round pipe
Adjustable wrenches are made for flat sides, not round surfaces.Using it as a hammer
This can damage the adjustment mechanism.Overtightening plumbing fittings
Many leaks come from damaged washers, cracked plastic nuts, or distorted fittings.Using one wrench when two are needed
On plumbing connections, one wrench may need to hold the valve or fitting while the other turns the nut.
Recommendations
Overall DIY Recommendation
8-inch adjustable wrench
Best for:
- General homeowner repairs
- Furniture and hardware
- Small plumbing fittings
- Appliance adjustments
Why it works:
- Easy to control
- Fits in tight areas
- Handles most common indoor repairs
Best Value Recommendation
Adjustable wrench set: 6-inch, 8-inch, and 10-inch
Best for:
- Homeowners building a basic toolkit
- Plumbing, furniture, appliances, and general repairs
- Jobs where you need two wrenches at once
Why it’s better:
- The small wrench fits tight spaces
- The medium wrench handles most jobs
- The larger wrench gives extra leverage when needed
Prosumer Recommendation
High-quality wide-jaw adjustable wrench
Best for:
- Frequent DIYers
- Plumbing repairs
- Working around fixtures and valves
- Anyone who wants less jaw wobble
What to look for:
- Smooth adjustment
- Minimal jaw play
- Comfortable grip
- Wide opening capacity
- Clear size markings
Fixers Club Tip
If you are working on plumbing, do not assume “tighter” means “better.” Many supply lines, compression fittings, and plastic nuts only need to be snug. If something keeps leaking after careful tightening, the issue may be the washer, ferrule, gasket, or thread type — not a lack of force.