<ul>
<li>A four-digit number (e.g. 2212)</li>
</ul>

<p>This number describes the dimensions of the stator inside the motor. The first two digits are the diameter (in mm) and the second two digits are the height (again, in mm.)</p>

<ul>
<li>A Kv number (<a href="https://drones.stackexchange.com/q/49/68">already explained on this site</a>)</li>
</ul>

<p>Kv - or <em>K<sub>v</sub></em> - has some really good answers at the provided link so I won't go into detail here, but it is approximately the RPM per volt.</p>

<ul>
<li>A number with N and P (e.g 12N14P)</li>
</ul>

<p>This describes the magnets present. The number before N is the number of electromagnets and the number before P is the number of permanent magnets. More magnets means more torque, but also higher cost and size.</p>

CC BY-SA 4.0
2020-05-31T16:09:55.787Z
I believe your first point is wrong. Those numbers measure the stator size, not the motor size.
ifconfig
CC BY-SA 4.0
2020-05-31T16:41:54.917Z
I think you're right; I knew they were dimensions so quickly Googled to check which way round and it seems the first few links make the same mistake - but searching for mechanical drawings clearly show the rotor is wider than the motor numbers. Answer updated.
Kralc
CC BY-SA 4.0
2020-06-01T08:33:26.567Z
The size numbers did originally refer to the stator (and generally still do for FPV quads, as 2204 was the original CDROM motor), but various Chinese makes have switched to use the overall motor size - presumably to make their motors sound bigger when ordering on-line. You need to actually check the dimensional diagram to see which scheme a particular motor is using. Here's an example that uses the overall size: https://oscarliang.com/1811-micro-brushless-outrunner-motor-review/
Robin Bennett
CC BY-SA 4.0
2020-05-31T08:51:46.277Z
2020-06-01T07:36:23.920Z
2020-06-01T07:36:23.920Z
Kralc
<p>Brushless DC (BLDC) motors can have a range of numbers on them:</p>

<ul>
<li>A four-digit number (e.g. 2212)</li>
<li>A Kv number (<a href="https://drones.stackexchange.com/q/49/68">already explained on this site</a>)</li>
<li>A number with N and P (e.g 12N14P)</li>
</ul>

<p>What do they mean?</p>

<hardware><brushless-motors>
What do the numbers mean on a brushless DC motor?
Kralc
# What do the numbers mean on a brushless DC motor?

(Asked by: username_0 on 2020-05-31)

Brushless DC (BLDC) motors can have a range of numbers on them:

* A four-digit number (e.g. 2212)
* A Kv number ([already explained on this site](https://drones.stackexchange.com/q/49/68))
* A number with N and P (e.g 12N14P)

What do they mean?

**Tags:** hardware, brushless-motors


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## 1 answers

### Answer by username_0 on 2020-05-31. Score: 9

* A four-digit number (e.g. 2212)

This number describes the dimensions of the stator inside the motor. The first two digits are the diameter (in mm) and the second two digits are the height (again, in mm.)

* A Kv number ([already explained on this site](https://drones.stackexchange.com/q/49/68))

Kv - or *Kv* - has some really good answers at the provided link so I won't go into detail here, but it is approximately the RPM per volt.

* A number with N and P (e.g 12N14P)

This describes the magnets present. The number before N is the number of electromagnets and the number before P is the number of permanent magnets. More magnets means more torque, but also higher cost and size.

> **Comments:**
> **username_1**: I believe your first point is wrong. Those numbers measure the stator size, not the motor size.  
> **username_0**: I think you're right; I knew they were dimensions so quickly Googled to check which way round and it seems the first few links make the same mistake - but searching for mechanical drawings clearly show the rotor is wider than the motor numbers. Answer updated.  
> **username_2**: The size numbers did originally refer to the stator (and generally still do for FPV quads, as 2204 was the original CDROM motor), but various Chinese makes have switched to use the overall motor size - presumably to make their motors sound bigger when ordering on-line. You need to actually check the dimensional diagram to see which scheme a particular motor is using. Here's an example that uses the overall size: https://oscarliang.com/1811-micro-brushless-outrunner-motor-review/  

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