Drill specification sheets are written for marketing departments, not for the people who use drills. A typical listing shows a peak torque figure that the tool will hit once under ideal conditions, a no-load speed measured without any resistance, and an Ah rating that tells you capacity but not runtime in real working conditions. If you know what each number actually means, and which ones matter for your specific use, you can buy the right drill rather than the one with the biggest headline figures.
This guide walks through every key specification you will see on a combi drill, explains what it means in practice, and gives you a framework for comparing tools honestly.
Torque: peak vs. working
Torque is the twisting force a drill applies to a fastener or drill bit. It is measured in Newton metres, or Nm. A common question is what Newton metres means in real terms. If you imagine a 1-metre-long wrench and you push on the end of it with 1kg of force, you are applying roughly 9.8 Nm of torque (force times distance). A cordless drill rated at 60 Nm is applying the equivalent of pushing that same wrench with about 6kg of force.
The number you see on the spec sheet is almost always peak torque, measured at stall (the point where the motor stops under maximum load). Working torque, which is what the tool delivers under sustained use, is lower. As a rough guide, working torque for most applications is somewhere between 40 and 70 percent of the peak figure. A drill rated at 90 Nm peak is not going to drive 90 Nm of resistance continuously; it is more likely to work at 40 to 60 Nm under typical conditions.
For most trade drilling tasks, torque is not the limiting factor anyway. Drilling 8mm holes in brick mortar or driving 60mm screws into timber is within the comfortable range of any drill rated above 50 Nm. Where torque matters more acutely is driving large-diameter hole saws, heavy lag bolts into hardwood, or mixing material in a bucket with a paddle, tasks where load is sustained and high.
What to look for: for general trade combi drill use, 60 Nm to 80 Nm is solid. For anything involving sustained heavy fastening or mixing, look at 80 Nm and above.
Clutch settings
Virtually all combi drills have an adjustable clutch, a rotating collar with numbered positions. The clutch is a torque-limiting mechanism: when the resistance on the bit reaches the clutch's set torque threshold, the clutch slips rather than letting the motor continue driving.
The purpose is twofold. First, it prevents over-driving screws: if you are fixing plasterboard or MDF screws that need to sit flush rather than below the surface, a correctly set clutch stops driving at exactly the right depth. Second, it reduces the chance of stripping screw heads under load.
The number of clutch positions varies. Budget drills may have 10 to 16; higher-specification tools often have 20 to 25. More positions give finer adjustment, which matters when working with a range of fastener sizes in different materials. A drill with 20 clutch positions gives you better precision for small screws in softwood than one with 10.
The highest position on the clutch collar is usually marked with a drill symbol rather than a number. This disengages the clutch entirely, allowing the full torque of the motor to be applied, which is what you want when drilling holes rather than driving screws.
What to look for: 18 or more clutch positions for versatile trade use. Fewer than 12 makes fine adjustment difficult.
No-load speed and gear settings
No-load speed is RPM measured with nothing attached to the chuck and no resistance on the bit. Like peak torque, this is a best-case figure. Under load, speed drops, and how quickly it drops depends on the motor design and the battery's ability to sustain current output.
Most combi drills have two gear settings. Low gear gives higher torque at lower speed; high gear gives higher speed at reduced torque. For slow, heavy work (driving large fasteners, drilling through masonry with a larger bit), low gear is appropriate. For fast, lighter work (smaller screws in softwood, small pilot holes), high gear reduces the time per fastener.
Common specifications look like: Low: 0-550 RPM, High: 0-2000 RPM. The 0 indicates variable speed from trigger pressure, not that the tool starts at zero and you have no control below full speed.
What to look for: for a general trade combi drill, low-gear top speed of around 450-600 RPM and high-gear top speed of 1800-2000 RPM covers the majority of applications.
Chuck size
Most combi drills have either a 10mm (3/8") or 13mm (1/2") keyless chuck. The chuck size determines the maximum shank diameter it can hold.
For trade use, a 13mm chuck is worth having. It accepts a wider range of bit shanks including larger hole saws, spade bits, and 13mm drill bits. The keyless mechanism means you can swap bits without a chuck key, which on a busy site is a practical necessity rather than a convenience.
Some compact or sub-compact drills use a 10mm chuck to save weight and length. For working in confined spaces (inside kitchen cabinets, under joists, inside wall cavities), the shorter drill body that a 10mm chuck usually accompanies can matter more than the slight reduction in bit capacity.
What to look for: 13mm keyless chuck for most trade applications. 10mm keyless if weight or compact size is the priority.
Impacts per minute and drilling modes
A combi drill has at least two modes: drill and driver. Most have three: drill, driver, and hammer. The hammer action is what distinguishes a combi drill from a standard drill driver.
In hammer mode, the drill bit moves forward and back rapidly while it rotates. The impacts per minute (IPM) figure tells you how many times per minute this hammering occurs. Typical figures are 25,000 to 48,000 IPM. More impacts per minute means more aggressive material penetration in masonry.
Hammer mode in a combi drill is adequate for drilling into brick and mortar for fixings. It is not equivalent to an SDS rotary hammer for sustained masonry drilling: SDS hammers use a different piston mechanism that delivers far more impact energy per blow. If your work involves drilling regularly into dense concrete, a dedicated SDS rotary hammer is the right tool. If you need to drill occasional fixings into brick walls between timber and other work, the hammer mode on a combi drill is sufficient.
What to look for: IPM above 30,000 for comfortable brick and mortar drilling. Do not buy a combi drill specifically for heavy concrete work expecting SDS-level performance.
Battery voltage and Ah: what actually determines runtime
All M18-class tools (from Milwaukee, Makita's 18V LXT, DeWalt XR, and the equivalent platforms) run on 18V nominal. Voltage determines the tool's power class; it does not meaningfully differ between brands at the 18V tier.
Amp hours (Ah) on the battery determines how long the tool runs between charges. A 5.0Ah battery holds 2.5 times the energy of a 2.0Ah battery. What this means in practice depends on the tool: a drill running at moderate load on a 5.0Ah battery will run approximately two and a half times as long between charges as on a 2.0Ah, assuming equal battery quality.
Weight increases with Ah. A 5.0Ah battery typically weighs around 750g to 900g; a 2.0Ah weighs around 350g to 450g. For all-day drilling work, the extra charge capacity is worth the weight. For lighter tasks or shorter sessions, a 2.0Ah reduces arm fatigue over a shift.
What to look for: 4.0Ah or 5.0Ah for general trade all-day use. 2.0Ah for occasional use or as a second battery for quick swaps. 6.0Ah or above for sustained heavy use only.
Weight
Drill weight matters more than spec sheets suggest. A drill that is 200g lighter does not sound significant, but over 100 repetitions of a fastening task in an overhead position, or a full day of fixing into walls at shoulder height, the cumulative difference in arm fatigue is real. Compact and sub-compact models sacrifice some torque and battery capacity for lower weight, and for some trades and tasks this trade-off is correct.
As a rough guide: a full-size 18V combi drill with a 5.0Ah battery weighs around 1.8kg to 2.2kg. A compact model with a 2.0Ah battery weighs around 1.2kg to 1.5kg.
What to look for: if you are drilling overhead for extended periods or working in tight spaces frequently, weight is a genuine specification, not just a comfort feature.