Impact driver 101—the basics
A few years ago,
were a specialty tool,
rare on job sites and
scarce on store
you'll see several
models at any tool
retailer and hear their
wherever there's construction.
When a tool gains popularity that fast,
you have to wonder what's going on.
And, more important,
what you're missing.
To sort out the pros and cons of impact drivers, we put them in the hands of our staff editors
and field editors, who are pros on the job and DIY guys at home. Here's what we learned:
Tip 1: It's all about torque
Impact drivers have one
over standard drills and
drivers: enormous torque.
Basically, that means you
can drive a big screw (or
bore a big hole) with a
small driver. In this photo,
we sank 3/8 x 10-in. self-drilling
lag screws into cedar
lumber. No pilot holes, no
Tip 2: Not just for driving screws
Impact drivers make great drills. With small bits (up to 1/4 in.
or so), they act like a drill—but at nearly twice the rpm of most
cordless drills. With bigger bits, they kick into high-torque
impact mode so you can bore a big hole with a small driver.
Tip 3: One-handed driving
With a standard driver, you
have to get your weight
behind the screw and push
hard. Otherwise, the bit will
“cam out” and chew up the
screw head. Not so with an
impact driver. The hammer
mechanism that produces
torque also creates some forward
pressure. That means
you don't have to push so
hard to avoid cam-out. Great
for one-handed, stretch-and-drive
Tip 4: The only driver you'll ever need?
Maybe. An impact driver will
handle just about any job,
and some of our testers have
already retired their old drivers.
But when high torque
isn't needed, most of us like
to avoid the noise and reach
for standard cordless drills or
Tip 5: Loud, really loud
An impact driver can bring
a heavy-metal drummer
to tears. Wear muffs or
earplugs—or get fitted for a
hearing aid. Your call.
Tip 6: It's not a hammer drill
An impact driver works kind
of like a hammer drill and
sounds a lot like one. But
it's no substitute for a hammer
drill. An impact driver's
innards are engineered to
generate torque, not powerful
Tip 7: Use hex shafts only
The chuck on an impact driver
makes for quick changes; just
slide the collar forward and
slip in the bit. But you'll have
to buy hex-shaft drill bits.
Regular bits won't work.
Tip 8: Small and smaller
Generally, there's a big torque difference between 12- and
18-volt models. But some of the 18-volt sluggers are amazingly
compact—not much bigger than their 12-volt cousins.
Big torque in a compact tool—that's why most of our testers
favored the 18-volt versions.
Driver Size Comparison
The 18-volt driver is only slight larger than the 12-volt driver. Both are compact.
Tip 9: Easy to handle
You might think that extreme
torque puts extreme strain on
your arm. Nope. For reasons
Isaac Newton could explain,
an impact driver actually
generates less wrist twist
than a standard driver. Don't
be fooled by the macho-man
feeling you get when you
effortlessly sink a big screw.
A little princess can do the
Tip 10: Consider a combo kit
For a few bucks more than an impact driver alone, you can
add a driver, a drill or a hammer drill to your tool collection.
This driver/impact driver twosome cost us just $25 more than
either tool sold separately. We couldn't resist.
Tip 11: Prepare for impact
Pick up a set of hex-shaft
accessories for about $25
(drill bits, driver bits, socket
adapters). You'll want most
of that stuff sooner or later,
and buying a kit will save you
a few bucks. Check the label
and get a set that's tough
enough for impact-driver duty.
Tip 12: They all look alike outside, but . . .
The difference is how they transfer torque from the motor to the chuck. On a standard drill or
driver, the motor and chuck are locked together through gears; as the workload increases, the
motor strains. An impact driver
behaves the same under
light loads. But when resistance
increases, a clutch-like
mechanism disengages the
motor from the chuck for a split
second. The motor continues to turn
and builds momentum. Then the
clutch re-engages with a slam, transferring
momentum to the chuck. All
of this happens about 50 times per
second, and the result is three or
four times as much torque from a
Impact driver, torque: 930 in.-lbs.
Standard driver, torque: 265 in.-lbs.
Impact Driver/Standard Driver Comparison
These two tools may look alike on the outside, but they operate differently.
Tip 13: Good for gearheads, tooThey don't have nearly
the torque of big impact
wrenches, but cordless
impact drivers can be a
time-saver when you tinker
with engines. They're perfect
for small engines, where less
torque is usually enough. For
automotive work, consider
an “angle” version, such as
the Craftsman shown later. Hitachi,
Makita, Ridgid and others
also make angle impact
Impact driver round-up and test results
It wasn't easy, but after weeks of
testing, retesting and arguing, we
settled on six favorites. The models
shown here are widely available at
home centers and hardware stores.
If you're willing to do some hunting,
you'll find several other models and
Tip: Watch for falling prices.
Don't be surprised if you find lower
price tags than listed here. We
watched prices during a six-week
period and saw prices drop on one
out of every four models shown here.
The discounts (sometimes sales,
sometimes permanent price cuts)
were in the 10 to 20 percent range.
Back to Top
Impact driver round-up and test results, continued
Our Over-All Favorite: Milwaukee 2650-22
Cost: $320 (Ouch!)
Torque: 1,400 in.-lbs.
Weight: 3.5 lbs.
Battery: 18V lithium (2)
Of our 10
testers, eight gave
this one the top
rating. In our
matched or exceeded the others. In
addition to raw power, it has all the features
we loved: a tool-belt hook, a bright
work light and a battery “fuel gauge.”
Bummer: No onboard bit storage.
Dissenting opinion: The DeWalt
DCF826KL is better. It has almost
as much torque, but it's lighter, more
compact and comfortable.
— Gary Wentz, senior editor
Compact Bargain: Hitachi WH10DFL
Torque: 840 in.-lbs.
Weight: 2.2 lbs.
Battery: 12V lithium (2)
You can find a smaller and lighter
driver, or more torque, or a lower price.
But for a combination of all three of
those traits, you can't beat this light,
powerful, affordable little gem.
Cramp warning: If you have big hands
or wear gloves on the job, the handle
might be too short. Otherwise, it's one
of the most comfortable drivers we
Big Power in Small Packages
Torque: 930 in.-lbs.
Weight: 2 lbs.
Battery: 12V lithium (2)
we tried, this one
takes two prizes:
lightest and most
compact. Plus, it's a
runner-up in torque.
Bonus points: Battery fuel gauge!
Torque: 950 in.-lbs.
Weight: 2.3 lbs.
Battery: 12V lithium (2)
This driver tops
our list for 12-volt
although it's taller
than most, it's
Dissenting opinion: Torque—it's THE
reason to have an impact driver. So
these 12-volt models just don't make
sense. Get an 18-volt.
— Max Lemberger, field editor
Terrific Torque, Low Prices
Torque: 1,600 in.-lbs.
Weight: 3.6 lbs.
Battery: 18V lithium (2)
You can't beat
at a price that's
about $100 below
most of the competition.
Skepticism: Top torque rating by far, but
in our tests it performed about the same
as other pro-grade 18-volt models.
Torque: 1,200 in.-lbs.
Weight: 4.5 lbs.
Battery: 18V NiCad (2)
Though not as
most of the
driver has plenty
of torque for
all but the
toughest jobs—and a crazy-low
Curmudgeon's note: I wouldn't buy anything with
a NiCad battery. Lithium is the only way to go.
—Travis Larson, senior editor