Quick answer: The four numbers that matter most on any power tool spec sheet are voltage (determines available energy), torque (rotational force in Nm), no-load speed (max RPM), and watt rating (sustained power output). Higher voltage does not always mean more power — it is the motor design, winding configuration, and electronic control that determine real-world cutting or drilling performance.
Most guides on this topic are written by reviewers who test tools. This one is written by engineers who build the motors inside those tools. Xiecheng's Motor Division has been producing power tool motors since 1986 — we currently manufacture over 2 million motor units annually across both brushed and BLDC motor platforms. When we explain what a spec number means, we are describing what we engineer on the production floor.
Voltage: What It Actually Controls
Voltage is the electrical pressure available to the motor. In cordless tools, it is set by the battery pack: a 5-cell lithium-ion pack delivers a nominal 18V (20V max), while a 3-cell pack delivers 10.8V (12V max). The "20V Max" and "18V" labels that confuse many buyers refer to the same cell configuration — 20V is the fully charged open-circuit voltage, 18V is the nominal working voltage under load.
Higher voltage gives the motor access to more energy per unit time, which enables higher peak power. But voltage alone does not determine performance. A poorly designed 20V motor can be outperformed by a well-designed 12V motor with optimized magnets, windings, and gear reduction. In our factory, we tune the same 46mm stator platform across 12V, 18V, and 20V configurations by adjusting the wire gauge and turn count in the copper windings.
Common Voltage Platforms in 2026
| Voltage Platform | Cell Count | Typical Applications | Weight Range |
|---|---|---|---|
| 12V (10.8V nominal) | 3S | Screwdrivers, compact drills, detail work | 0.8–1.5 kg |
| 18V / 20V Max | 5S | Drills, circular saws, jig saws, reciprocating saws | 1.5–3.5 kg |
| 36V / 40V Max | 10S | Heavy-duty saws, demolition, lawn equipment | 3.0–6.0 kg |
| 54V–60V FlexVolt | 15S | Table saws, sliding miter saws, large-format cutting | 4.0–8.0 kg |
Torque: The Force Behind Every Cut and Drive
Torque is the rotational force the motor delivers to the output shaft, measured in Newton-meters (Nm). It is what pushes a saw blade through hardwood or drives a fastener into steel. Most tool spec sheets list two torque values: hard torque (driving into rigid material like metal) and soft torque (driving into yielding material like wood).
A typical 18V cordless drill produces 40–80 Nm of peak torque. A professional-grade 18V impact driver can deliver 180–220 Nm. Our compound miter saws use corded motors rated for 15–25 Nm of continuous torque at the blade, which translates to 4,200–5,000 RPM at the cutting edge through a gear reduction system.
The relationship between torque and speed follows a simple rule: Power (W) = Torque (Nm) × Speed (rad/s), or approximately Power (W) = Torque (Nm) × RPM ÷ 9.55. A motor can trade torque for speed and vice versa while maintaining the same wattage. This is why gearboxes exist — they multiply torque at the expense of speed.
RPM: No-Load Speed vs Under-Load Speed
RPM (revolutions per minute) on the spec sheet is almost always the no-load speed — the maximum speed when the tool is running freely with no resistance. Under actual cutting or drilling load, the speed drops by 15–40% depending on the material and motor design.
For OEM engineers, the critical metric is the speed-torque curve: the relationship between motor speed and torque as load increases. A well-designed motor maintains a flatter curve — speed drops gradually as load increases, rather than falling off a cliff. This is where brushless motors with electronic torque control have a decisive advantage over brushed designs.
Speed Requirements by Tool Type
| Tool Category | Typical No-Load RPM | Under-Load RPM | Key Spec Focus |
|---|---|---|---|
| Circular Saws | 3,500–5,800 RPM | 2,800–4,500 RPM | Blade tip speed (m/s) |
| Jig Saws | 500–3,100 SPM | 400–2,500 SPM | Stroke length × SPM |
| Reciprocating Saws | 0–3,000 SPM | 0–2,200 SPM | Variable speed range |
| Miter Saws | 3,800–5,000 RPM | 3,200–4,200 RPM | Torque at start-up |
| Belt Sanders | 250–450 m/min (belt) | 200–380 m/min | Belt surface speed |
| Cordless Drills | 0–1,800 RPM | 0–1,200 RPM | Torque (Nm) + clutch settings |
Watt Rating: Corded vs Cordless
For corded tools, the watt rating on the spec sheet is the input power — the electrical power drawn from the wall. A 1,500W circular saw does not deliver 1,500W of cutting power; after motor efficiency losses (typically 60–75% for brushed, 85–92% for brushless), the actual mechanical output is 900–1,380W.
Cordless tools rarely list wattage directly. Instead, you calculate it: Watts = Voltage × Amperage. An 18V tool drawing 30A from the battery pack produces 540W of input power. With a brushless motor at 90% efficiency, that is roughly 486W of mechanical output — which is why cordless tools still have not fully replaced corded models for sustained heavy-duty cuts.
In our production testing lab, we measure output power using a dynamometer that applies calibrated resistance to the spindle. Our 1,600W corded 210mm circular saw delivers approximately 1,100W at the blade — a 68.7% efficiency rate typical for a quality universal motor.
Motor Type: How It Changes Every Specification
The motor type — brushed universal, brushed DC, or brushless DC — fundamentally alters what every other spec number means in practice. Here is a comparison based on our actual production data:
| Spec Parameter | Brushed Universal (AC/DC) | Brushed DC | Brushless DC (BLDC) |
|---|---|---|---|
| Efficiency | 55–70% | 65–78% | 85–92% |
| Operating Temp (continuous) | 120–160°C winding | 90–130°C winding | 60–90°C winding |
| Speed Control | Trigger/triac (basic) | PWM (moderate) | FOC/sinusoidal (precise) |
| Typical Lifespan | 300–600 hours | 200–500 hours | 1,000–2,000+ hours |
| Noise Level | 75–90 dB | 70–85 dB | 55–70 dB |
| OEM Unit Cost | Baseline (1×) | 1.1–1.3× | 1.8–2.5× (motor + ESC) |
| Battery Runtime (same task) | N/A (corded) | Baseline | 25–50% longer |
For a deeper dive into brushed vs brushless technology, read our complete brushless vs brushed motor comparison.
How to Read a Spec Sheet: What Manufacturers Don't Tell You
After 30+ years of building motors and tools, here are the spec-reading shortcuts our engineers wish every buyer knew:
- Ignore no-load speed for cutting tools. A miter saw rated at 5,000 RPM no-load will run at 3,800–4,200 RPM during a crosscut through 2×4 lumber. The under-load speed is what determines cut quality.
- "20V Max" and "18V" are the same platform. Both use 5-cell lithium-ion packs. The nominal working voltage is 18V; 20V is the peak at full charge. Do not compare them as different power classes.
- Torque without speed is meaningless. A drill claiming 80 Nm but at only 400 RPM is slower than one delivering 60 Nm at 1,500 RPM. Always check both numbers together.
- Input watts ≠ output watts. A 2,000W corded tool delivers roughly 1,200–1,700W of mechanical output depending on motor type. Compare output watts when possible.
- Amp-hours (Ah) measure runtime, not power. A 5.0 Ah battery does not make a tool more powerful than a 2.0 Ah battery — it just runs 2.5× longer before needing a recharge.
- Check the gear reduction ratio. A 2-speed gearbox (e.g. 1:10 for high-torque, 1:4 for high-speed) dramatically changes the output characteristics. Professional tools use metal planetary gears; budget tools often use nylon gears that wear faster under load.
What OEM Buyers Should Specify When Ordering Motors
If you are sourcing power tool motors for your own tool line, here are the critical specifications to define in your purchase order:
- Nominal voltage and voltage range — Not just 18V, but the operating range (15V depleted to 21V freshly charged).
- Rated torque and rated speed — These are the continuous-duty values, not peak. Define both at the motor shaft and at the tool output.
- Stall torque and stall current — Maximum force the motor can exert before stopping. This sets your protection circuit requirements.
- Motor OD and shaft dimensions — Must fit your tool housing. Common power tool motor diameters are 36mm, 42mm, 46mm, and 54mm.
- Thermal class — Class B (130°C), F (155°C), or H (180°C) insulation determines continuous duty limits.
- Certifications required — CE, UL, GS, EMC. Our motors carry GS, CE, UL, and EMC certifications under IATF 16949 quality management.
Xiecheng produces both complete power tools and standalone motor assemblies. Whether you need a 540-series LVDC motor for a drill or a 4635 BLDC motor for a professional saw, our engineers work with you to match the motor specification to your application requirements.
Related Guides
- Brushless vs Brushed Motor: Complete Comparison
- BLDC Motors in Power Tools: Why Every OEM Is Switching
- Vertical Integration in Power Tool Manufacturing
- OEM Power Tools: How to Partner with a Chinese Factory
Ready to Discuss Motor Specifications?
Whether you are an OEM designing a new tool platform, a distributor evaluating product specs, or an engineer comparing motor technologies — our Motor Division team can walk you through the specifications that matter for your application. With 260 engineers on staff and 40 years of motor manufacturing experience, we speak your language.