Choosing an Impact Driver: A Complete Guide
An impact driver is one of the most versatile and frequently used tools in construction. This guide covers everything you need to know about choosing the right impact driver, from understanding torque and speed ratings to comparing battery platforms and evaluating features from leading manufacturers.
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What is an Impact Driver?
An impact driver is a power tool designed specifically for driving screws and fasteners. Unlike a standard drill, which applies continuous rotational force, an impact driver combines rotational force with concussive blows (impacts) that drive the fastener in short, rapid bursts. This impact mechanism delivers significantly more torque than a standard drill, making impact drivers ideal for driving long structural screws, lag bolts, and other heavy fasteners.
The impact mechanism also reduces the torque reaction felt by the operator. When a standard drill encounters resistance, the torque is transferred to the operator's wrist, which can be fatiguing and even injurious during extended use. An impact driver's concussive action absorbs much of this torque reaction, making it more comfortable to use for long periods and reducing the risk of wrist strain.
Impact drivers use hex-shank bits, which are quick-change and don't require a chuck. This makes bit changes faster than with a standard drill. However, impact drivers cannot be used for drilling (with standard round-shank drill bits) without a hex-shank drill bit adapter. Most contractors use both an impact driver for fastening and a drill for drilling.
Key Specifications to Consider
- Torque (measured in inch-pounds or Newton-meters) — the rotational force the tool can deliver
- Speed (measured in RPM) — how fast the chuck spins when not under load
- Impacts per minute (IPM) — how many concussive blows per minute the tool delivers
- Battery platform — which cordless battery system the tool is compatible with
- Brushless vs. brushed motor — brushless offers more power, longer runtime, and extended tool life
- Variable speed settings — allows the user to adjust speed for different applications
- LED work light — illuminates the work area when the tool is in use
Understanding Torque Ratings
Torque is the most important specification for an impact driver, as it determines the size and length of fasteners the tool can effectively drive. Modern impact drivers typically deliver between 1,000 and 2,000 inch-pounds of torque. For context, a standard drill typically delivers 400-600 inch-pounds — so even a modest impact driver provides significantly more driving power.
For most construction applications, an impact driver with 1,500 to 1,800 inch-pounds of torque is sufficient. This range can drive 4-inch and longer structural screws, lag bolts, and other heavy fasteners without straining the tool. For extremely demanding applications like driving large lag bolts into hardwood, consider a higher-torque model (1,800+ inch-pounds).
It's worth noting that more torque isn't always better. For delicate applications or when driving smaller fasteners, excessive torque can twist off screw heads or overdrive fasteners. Many impact drivers feature multiple speed and torque settings that allow the user to reduce power for delicate applications. This adjustability makes a high-torque impact driver more versatile.
Battery Platform Considerations
Choosing an impact driver also means choosing a battery platform, and this decision affects all future cordless tool purchases. Most contractors standardize on one battery platform so that batteries and chargers are interchangeable across all their cordless tools. This reduces the number of batteries and chargers needed and simplifies tool management.
Milwaukee's M18 platform is one of the most popular among professional contractors, offering an extensive selection of cordless tools, excellent performance, and wide availability. DeWalt's 20V MAX platform is similarly popular, with a comparable tool selection and performance. Makita's 18V LXT platform is known for precision engineering and ergonomic design. Metabo HPT's MultiVolt platform offers the unique ability to run tools on battery or AC power.
When choosing a platform, consider the full range of cordless tools you may want in the future — not just the impact driver. If you plan to build a complete cordless toolkit, the platform with the broadest tool selection that meets your needs and budget is the best choice. Our team can help you compare platforms and select the one that's right for you.
Brushless vs. Brushed Motors
Modern impact drivers are available with either brushed or brushless motors. Brushless motors (often branded as BL, FUEL, or similar) offer significant advantages over traditional brushed motors: more power, longer runtime per battery charge, and extended tool life. Brushless motors also run cooler and require less maintenance.
The primary disadvantage of brushless motors is cost — brushless tools are typically 30-50% more expensive than equivalent brushed models. However, the performance and longevity advantages often justify the higher cost, especially for contractors who use their tools daily. For professional use, brushless impact drivers are strongly recommended.
All major manufacturers now offer brushless impact drivers. Milwaukee's M18 FUEL line, DeWalt's 20V MAX XR line, Makita's LXT BL line, and Metabo HPT's MultiVolt line all feature brushless technology. These tools represent the current state of the art in cordless impact driver performance.
Choosing the Right Impact Driver for You
At Fastener Express, we carry impact drivers from Milwaukee, DeWalt, Makita, and Metabo HPT. Our team can help you compare models, evaluate specifications, and choose the right impact driver for your specific needs and budget. We also carry compatible driver bits, socket adapters, and other accessories.
For contractors who need a complete cordless toolkit, we can help you select a platform and build a coordinated tool package that shares batteries and chargers across all your cordless tools. This approach is more cost-effective than buying individual tools from different platforms and ensures that you always have charged batteries available.
We also offer tool repair services for impact drivers, including battery testing, switch replacement, and motor service. Our preventive maintenance programs can keep your cordless tools running at peak performance. Contact us to discuss your impact driver needs or to set up a contractor account for volume pricing on tools and accessories.
Frequently Asked Questions
What's the difference between an impact driver and a drill?
An impact driver combines rotational force with concussive impacts for driving fasteners, delivering more torque than a drill. A drill applies continuous rotational force and is better for drilling holes. Most contractors use both tools.
How much torque do I need in an impact driver?
For most construction applications, 1,500 to 1,800 inch-pounds of torque is sufficient. This range can drive 4-inch structural screws and lag bolts. For extremely demanding applications, consider 1,800+ inch-pounds.
Is a brushless impact driver worth the extra cost?
Yes, for professional use, brushless impact drivers offer more power, longer runtime, and extended tool life. The 30-50% price premium is typically justified for contractors who use their tools daily.
Which battery platform should I choose?
Choose based on the full range of cordless tools you may want, as batteries and chargers are interchangeable within a platform. Milwaukee M18, DeWalt 20V MAX, Makita 18V LXT, and Metabo HPT MultiVolt are all excellent professional-grade platforms.
Can I use an impact driver for drilling?
Impact drivers use hex-shank bits and don't have a traditional chuck, so you'll need hex-shank drill bits or an adapter for drilling. Most contractors use an impact driver for fastening and a drill for drilling.