Pen pressure


Pressure is the physical force being exerted on its tip. Remember that it is the pen that measure the pressure, not the tablet surface.

The Initial Activation Force (IAF) is the smallest amount of pressure that an EMR pen will detect and report. The maximum pressure the maximum amount of pressure that an EMR pen can detect and report. The pressure range is the range of physical force the pen is capable of sensing and outputting as pressure. In other words its lower bound is the IAF and its upper bound is the maximum pressure.

  • A wide pressure range is very desirable. It contributes a lot to a good pressure experience. A wider pressure range is even more important than the number of pressure levels.

  • A lower IAF is good because it allows you to draw finer details better.

Rating scale for IAF and max pressure

To get a broad view into how different pens handle IAF and max pressure, consult this document: Pen pressure range comparison

The importance of low IAF

Some people REALLY need that EXCELLENT IAF of <1gf.

Others like (myself included) work fine with a 3gf IAF. I definitely notice the difference but it doesn't effect me with the kind of art I create.

Pressure levels

These days tablet brands say that they can handle 8K (8192) levels of pressure. Some tablets even claim to support 16K pressure levels.

Pressure level hype

Don't get caught up in hype about pressure levels.

I claim you only need 2048 levels of pressure (and probably even less than that). As a quick example watch this 35 second video:

Disabling pressure

Sometimes it is useful to disable pen pressure. For options on how to do so go here: Disable pen pressure.


  • Pens - even if they are of the same model - differ a little in their pressure sensitivity

  • Pressure sensors are subject to wear. Over time, you may find that a pen is less sensitive to pressure than it used to be. Though in practice, I have never experienced this in any noticable way myself.

How EMR pens measure pressure

There are two techniques. The techniques have two things in common:

  • The pressure is measured by the pen.

  • Then transmitted to the tablet.

The modern technique: the nib contacts a pressure sensor inside the pen. The nib goes through the hollow ferrite rod and then the nib touches the pressure sensor deeper in the pen. The ferrite rod does NOT move. The pen digitally encodes pressure data into the electromagnetic signal generated by the inductor coil. The tablet then decodes the digital pressure information from the signal.

The very old technique: Nib goes into the hollow ferrite rod but does not come out the other side. The nib is shaped in such a way that it is firmly embedded in ferrite rod. Ads the nib moves, so to does the ferrite rod. The movement of the ferrite rod changes the resonant frequency of the inductor coil. That change in frequency is then sensed by the tablet and translated to pressure.

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