Nothing ruins a project faster than snapping a screw head off, stripping a slot into a shiny crater, or watching a chair leg crack because you drove the fastener too deep. Impact drivers are strong — often stronger than the fastener or the material you’re driving it into — and that mismatch is exactly what causes those headaches. Without a clear torque target, most people either baby the trigger and end up with proud screw heads, or lean on full power and split wood, cam out bits, or shear off bolts.
The fix isn’t a stronger arm or a fancier tool. It’s knowing the right torque range for the fastener size and material you’re working with, then dialing your driver to match. This guide gives you a complete impact driver torque chart — in both inch-pounds and Newton-meters — organized by screw gauge, bolt diameter, and material, from drywall to hardwood to sheet metal to masonry anchors. You’ll also learn how to translate those numbers into your driver’s speed settings, when an impact driver isn’t the right tool at all, and the habit that strips more screws than any other.
Quick answer: torque output varies a lot by brand and model, so treat any single number as a ballpark. As a rough guide, a #8 wood screw in softwood typically needs only 40–90 in-lbs, lag bolts have no published standard torque spec (follow the fastener manufacturer’s stated value and finish by hand just before the head seats to avoid over-torquing), and a drywall screw needs just 20–40 in-lbs. Matching torque to fastener size and material — rather than just mashing the trigger — is one of the most effective ways to prevent stripped heads, snapped shanks, and split material.
Quick Facts: Impact Driver Torque at a Glance
| Spec | Typical Range |
|---|---|
| Impact driver torque output (varies widely by model) | 1,000–3,000+ in-lbs (113–339 Nm) |
| Small screws (drywall, trim, #4–#6) | 15–45 in-lbs (1.7–5 Nm) |
| Wood screws, softwood (#8–#10) | 40–120 in-lbs (4.5–13.5 Nm) |
| Wood screws, hardwood (#8–#10) | 120–180 in-lbs (13.5–20 Nm) |
| Sheet metal screws (16–24 gauge) | 40–90 in-lbs (4.5–10 Nm) |
| Lag bolts/screws (3/8 in–1/2 in) | No published standard torque spec — follow manufacturer’s stated value[source]; finish by hand just before the head seats |
| Masonry/concrete anchors (1/4 in–3/8 in) | Roughly 48–360 in-lbs (5.4–41 Nm) — e.g., 4 ft-lbs for 1/4 in and 30 ft-lbs for 3/8 in per Simpson Strong-Bolt 2 data; always per anchor manufacturer’s stated torque |
| Speed settings & RPM range | 0–3,900+ RPM (varies by brand), 2–4 settings |
| Unit conversion | 1 ft-lb = 12 in-lbs; 1 Nm ≈ 8.85 in-lbs |
Treat the numbers above as general starting points gathered from common fastener and tool references, not certified specs. Always confirm against your fastener’s packaging and your driver’s manual for anything that matters structurally.
Understanding Impact Driver Torque Settings
Before you can use a torque chart, it helps to know what the numbers mean and how your tool actually applies them.
Torque Units, Explained
Impact drivers are almost always rated in inch-pounds (in-lbs) because the fasteners they drive are small. Larger tools, like impact wrenches for lug nuts, use foot-pounds (ft-lbs) instead. The conversion is simple: 12 in-lbs equals 1 ft-lb. Metric spec sheets use Newton-meters (Nm), where 1 Nm is roughly equal to 8.85 in-lbs, and 1 in-lb equals about 0.113 Nm. Keep a calculator handy if you’re cross-referencing a metric fastener spec against an imperial driver rating.
Speed Settings vs. True Torque Control
Most impact drivers don’t have a numbered torque dial the way a torque wrench does. Instead, they offer roughly 2 to 4 speed or power settings that indirectly limit torque by controlling motor speed and impact frequency. Top speeds vary more than you might expect between brands: some models top out around 2,900 RPM on their highest setting, while others — including several current brushless models — climb well past 3,000 RPM, with a few reaching close to 3,900 RPM. Higher-end brushless drivers sometimes add electronic torque control with settings labeled for specific fastener types (wood, metal, self-tapping). Always check your owner’s manual, since exact RPM and torque figures vary by brand and model.
| Setting | Approx. RPM | Approx. Impacts Per Minute | Best For |
|---|---|---|---|
| 1 (Low) | 0–1,000 | 0–1,200 | Drywall, trim, small screws, delicate materials |
| 2 (Medium) | 0–2,000 | 0–2,400 | General wood screws, deck screws |
| 3 (High) | 0–2,900, up to ~3,900 on some models | 0–3,200 | Lag bolts, large fasteners, dense hardwood |
| 4 (Precision/Self-Tap, select models) | Electronically limited | Varies | Sheet metal, self-tapping screws, delicate finish work |
Impact Driver Torque Chart by Fastener Material
Material matters as much as size. The same #8 screw needs very different torque in soft pine than in dense oak, and metal or masonry fasteners behave differently again. Use this table as your starting point, then fine-tune based on how the fastener feels going in.
| Material | Example Fastener | Torque (in-lbs) | Torque (Nm) | Suggested Setting |
|---|---|---|---|---|
| Drywall/gypsum board | #6 drywall screw | 20–40 | 2.3–4.5 | Low |
| Softwood (pine, fir, spruce) | #8 wood screw | 40–90 | 4.5–10 | Low–Medium |
| Hardwood (oak, maple, cherry) | #8–#10 wood screw | 120–180 | 13.5–20 | Medium–High, pre-drill recommended |
| Plywood, MDF, particleboard | #6–#8 screw | 30–70 | 3.4–7.9 | Low |
| Sheet metal (16–24 gauge) | Self-tapping screw | 40–90 | 4.5–10 | Low–Medium |
| Structural steel connectors | #10–#14 tek screw | Follow the screw manufacturer’s stated rating on the packaging | — | Medium |
| Plastic/PVC trim | Trim head screw | 15–30 | 1.7–3.4 | Low |
| Masonry/concrete | 1/4 in–3/8 in concrete anchor | 48–360 | 5.4–41 | Set to the anchor manufacturer’s stated torque with a torque wrench (e.g., about 4 ft-lbs for 1/4 in, 25–30 ft-lbs for 3/8 in) |
| Composite decking | #8–#10 deck screw | 100–150 | 11–17 | Medium |
These ranges are general starting points, not exact engineering specifications. For anything load-bearing — deck framing, railing posts, structural anchors — check the fastener manufacturer’s published torque spec or the project’s engineered drawings, and when in doubt, have a licensed contractor verify the connection.
Impact Driver Torque Chart by Fastener Size
If you don’t know the material specifics but do know the fastener’s gauge or diameter, this table gives you a reasonable middle-ground torque range. Cross-check against the material table above for a tighter number.
| Screw Gauge / Bolt Size | Diameter (in) | Torque (in-lbs) | Torque (Nm) |
|---|---|---|---|
| #4 | 0.112 | 15–30 | 1.7–3.4 |
| #6 | 0.138 | 25–55 | 2.8–6.2 |
| #8 | 0.164 | 40–100 | 4.5–11.3 |
| #10 | 0.190 | 60–130 | 6.8–14.7 |
| #12 | 0.216 | 90–160 | 10.2–18.1 |
| 1/4 in | 0.250 | 48–144 (grade-dependent: ~4 ft-lbs Grade 2, ~8 ft-lbs Grade 5, ~12 ft-lbs Grade 8, dry) | 5.4–16 |
| 5/16 in | 0.3125 | 130–290 (grade-dependent: ~11 ft-lbs Grade 2, ~17 ft-lbs Grade 5, ~24 ft-lbs Grade 8, dry) | 15–33 |
| 3/8 in | 0.375 | No published standard; follow manufacturer’s rating | — |
| 1/2 in | 0.500 | No published standard; follow manufacturer’s rating | — |
How to Set Your Impact Driver’s Torque Correctly
- Identify the fastener’s material and approximate size (gauge for screws, diameter for bolts).
- Look up the torque range in the tables above and note the suggested speed setting.
- Set your driver to the lowest speed setting that matches your target range. It’s easier to bump up a setting than to back out an overdriven screw.
- Test on a scrap piece of the same material before committing to the real workpiece, especially for hardwood, thin sheet metal, or finish-grade trim.
- Drive the fastener in short bursts near the end, easing off the trigger as the head seats flush. The impact mechanism engages with a distinct rattling sound — that’s your cue to ease up.
- For anything structural or safety-critical — ledger boards, joist hangers, railing hardware, load-rated anchors — use a calibrated torque wrench instead of an impact driver, and follow the fastener manufacturer’s exact torque spec rather than a general chart like this one.
Common Mistakes That Strip Screws or Snap Fastener Heads
- Maxing out the speed setting for small screws. Drywall and trim screws almost never need more than 40 in-lbs; full power will spin right through the drywall paper or snap the head.
- Skipping the pilot hole in hardwood. Dense wood like oak or maple resists the screw enough that torque builds faster than the wood can yield, often snapping the screw shank. A properly sized pilot hole — slightly narrower than the screw’s threaded shank — gives the wood somewhere to displace and largely solves this.
- Using the wrong bit size. A worn or undersized bit cams out under torque, chewing up the screw head and the surrounding material.
- Ignoring the fastener’s rated strength. Cheap screws snap well below the torque an impact driver can generate; check the packaging for a shear or tensile rating if the connection matters.
- Overdriving thin sheet metal. Self-tapping screws in 20–24 gauge metal can strip the hole they just cut if you keep the trigger down after the head seats.
Wear eye protection when driving screws with an impact driver. Bits can shatter, cam out, or send small metal shavings flying, especially at higher torque settings.
When an Impact Driver Isn’t the Right Tool
Impact drivers are excellent for speed and convenience, but they deliver torque in rotational pulses, which makes precise, repeatable torque control difficult. For a handful of situations, reach for something else instead:
- Structural framing connections. Deck ledger boards, joist hangers, hurricane ties, and other code-regulated connections typically have manufacturer-specified fasteners and torque values tied to load ratings. As a general rule, these should be set with a calibrated torque wrench, and anything affecting a building’s structure should be verified by a licensed contractor.
- Automotive and appliance assembly. Wheel lug nuts, engine components, and gas appliance fittings have exact torque specs where both under- and over-tightening cause failure; use the torque wrench setting the manufacturer publishes.
- Fine furniture and cabinetry. Delicate joinery and finish hardware benefit from a drill/driver with a mechanical clutch rather than an impact driver’s pulsing power.
Frequently Asked Questions
What torque should I use for deck screws?
Most #8 to #10 composite or wood deck screws drive well at 100–150 in-lbs (11–17 Nm) on a medium speed setting. Pre-drill near board ends to prevent splitting.
Can I use an impact driver for lag bolts?
Yes, for general construction lag bolts in the 3/8-inch to 1/2-inch range, most impact drivers can drive them, but there’s no published standard torque spec for lag screws — follow the fastener manufacturer’s stated value, and finish by hand just before the head seats to avoid over-torquing. For structural or load-rated lag connections, confirm the manufacturer’s torque spec and consider finishing with a torque wrench.
What’s the difference between in-lbs and ft-lbs?
They’re both units of torque; 12 inch-pounds equal 1 foot-pound. Impact drivers use the smaller in-lbs unit because fastener torque values are usually under a few hundred in-lbs, which would be an awkward fraction in foot-pounds.
How do I convert Newton-meters to inch-pounds?
Multiply the Nm value by 8.85. For example, 20 Nm converts to about 177 in-lbs. To go the other way, multiply in-lbs by 0.113 to get Nm.
Do impact drivers have adjustable torque like a drill?
Not exactly. Standard impact drivers adjust speed and impact frequency across roughly 2 to 4 settings rather than a true torque clutch, and top speeds vary a lot by model — some reach nearly 4,000 RPM on their highest setting. Some newer brushless models add electronic torque limiting with settings tuned for wood, metal, or self-tapping fasteners — check your specific model’s manual for exact in-lb figures.
What happens if torque is too high?
Excess torque strips screw heads, snaps fastener shanks, cracks wood near the fastener, strips out pre-cut threads in sheet metal, and can overdrive screws below the material surface, weakening the joint.
What impact driver torque is safe for drywall?
Aim for 20–40 in-lbs (2.3–4.5 Nm) on the lowest speed setting. Drywall screws need just enough torque to dimple the paper slightly without tearing through it.
Should I use a torque wrench for structural framing?
Yes, as a general practice. Structural connections — ledger boards, joist hangers, railing posts, and similar load-bearing hardware — should be fastened according to the manufacturer’s published torque specification using a calibrated torque wrench, and structural work should be verified by a licensed contractor where local code requires it.
Reviewed and edited by Jason Paik. Spotted an error? Tell us — we verify and correct. See how we create content.