Power Rating FAQ
What is torque?
Torque is a measurement of how much force is required to turn an object. A common drill myth is that the higher the torque rating, the faster the drill will complete an application. Torque is not an indicator of how fast an object will turn..
What is speed (RPM’s)?
Speed is a rate of motion or how fast something turns. For a drill, it is how fast a bit turns when it is not applied to material. RPM’s means rotations per minute.
What is power?
Power is the combination of speed and torque. To the professional drill user, it is an indication of how fast a drill will complete an application.
What is Max Watts Out (MWO)?
MWO is the maximum power of the drill’s motor. It is a power measurement for the motor only.
What is Unit Watts Out (UWO)?
UWO is the maximum power output for a drill system. It takes into account the efficiency of the entire drill system (transmission, clutch, and chuck). UWO measures the power of the drill at the chuck.
What is the difference between MWO and UWO?
MWO gives the power output for only the motor whereas UWO gives the power output of the total drill system. UWO takes the transmission, clutch, and chuck into account. A drill that has MWO of 600 may only have a UWO of 500. This is a 17% loss in power due to an inefficient transfer of power from the motor through the transmission, clutch, and chuck. If a drill has a MWO of 600 and the UWO of 560, there is only a 7% loss of power. Measuring the drill’s power at the chuck is more indicative of the drills performance. The drill's UWO is what the user experiences on the job site.
How is a torque rating generated?
The process for which a torque rating is generated is a standard procedure in the industry. A drill is mounted into a rig (piece of testing equipment). The chuck of the drill is locked down onto a fixed spindle (spindle does not rotate). The drill is fully powered. The spindle, which is fixed, measures the force at which the drill is trying to turn it. The torque rating is a measurement of the amount of force that is being applied to the spindle at 0 RPM.
Example: Have you ever bogged down a drill? If you have, remember as the drill is locked into a piece of material, the drill cannot turn the chuck. If you keep applying pressure to the trigger, you can feel the energy in the drill trying to turn the chuck but nothing is moving. This example is similar to how a torque rating is generated.
What is the difference between peak torque and sustained torque?
As mentioned above, the process for which torque is measured is a standard in the industry. The way the data is interpreted is not. When the drill chuck is mounted onto a fixed spindle, and the drill’s trigger is depressed, an initial burst of energy will occur. This initial burst of energy is referred to as peak torque. As the trigger continues to be depressed, that initial burst of energy decreases to a constant level. This level is known as the drills sustained torque. Some manufacturers will choose their torque rating based on peak torque (which occurs in less than half a second) versus the sustained torque which occurs over an extended period of time. An example of a torque rating graph is shown below:
How is a power rating (UWO) generated?
Measuring a drill's power output is a common procedure in the industry. When manufacturers refer to power, they could be referring to UWO or MWO. A UWO rating is generated using a process that can reflect the user’s applications. A drill is mounted into a rig. The chuck of the drill is locked onto a spindle. The spindle in this test is not fixed and thus rotates as the drill is fully powered. With the chuck spinning at the maximum RPM (could be 1st, 2nd, or 3rd speed) torque loads are increasingly applied to the spindle. As the torque loads increase, the drill slows down. These torque loads can reflect the user’s applications. The drill’s Unit Watts Out is the point of the drills maximum power output (Power, remember, is a combination of speed and torque). It is found where the drills speed and torque level are the highest. Below is an example of a power rating chart: 
Is this power measurement new to the industry?
No. It is a measurement that has been around for many years. Power has just never been used as a rating specification (UWO) or been marketed. Since more power equals an increase in application performance, the UWO rating gives the user an indication of the drill’s performance level.
If a user has multiple drills and has one bit and one piece of material, would the torque required to turn the bit into the piece of material vary based on the drill used?
No. As long as the user is using the same bit and the same piece of material, it does not matter what drill (corded or cordless, 3/8" or 1/2", voltage or amp, etc.) is being used - The torque required will not change. However, if the user uses a bit that is of a different brand or design, or uses a different piece of material, or applies a different amount of pressure to one drill versus the other, the torque required differs.
What is the required torque for the most common user applications?
Below details the torque required for the most common bits and materials being used the professional drill user.
How does a drill achieve superior application performance?
The key to superior drill performance is to deliver the highest speed at the required torque level. The faster the drill turns at the required torque levels, the faster the drill completes an application.
What is the easiest way to explain the power rating to someone who normally uses torque as an indicator for a drills performance?
- Common Drill Myth: Higher the torque rating, the faster the drill will complete applications.
- Torque is the force to turn an object. Not how fast an object turns.
- Torque and speed are inverse. Higher the torque, the slower the applications are completed.
- Torque ratings are generated at 0 RPM (industry standard). No indication of how fast applications are completed.
- Best way to rate drill performance: Power
- Speed (how fast a drill turns) & Torque (force required to turn an object) = Power (time to complete an application)
- Power directly correlates to productivity. Gives users accurate rating in choosing the best performing drill.
- MWO is the power of the motor. UWO is the power of the drill system. UWO takes the drills transmission, clutch, and chuck into account. A drill’s UWO is what the user experiences on the jobsite.
Does the power rating (UWO) apply to corded drills?
Yes. You will see corded drills adopt this performance rating in the near future. Having a rating indicative of a drill’s performance level not only applies to cordless drills but also corded.