> For the complete documentation index, see [llms.txt](https://docs.sevenpens.com/drawtab/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.sevenpens.com/drawtab/core/pressure.md). # Pressure ## Overview **Pressure** is the physical force being exerted on the pen tip. ## Key concepts * **The pen senses pressure**, not the tablet. The pen communicates the pressure it detects to the tablet. * The [IAF](/drawtab/core/pressure/iaf.md) is the smallest amount of pressure an EMR pen will detect and report. * The [Pen pressure range](/drawtab/core/pressure/pen-pressure-range.md) is the range of physical force the pen can sense and output as pressure. In other words, its lower bound is the IAF and its upper bound is the **maximum pressure**. * A tablet splits the pressure range into segments called [Pen pressure levels](/drawtab/core/pressure/pen-pressure-levels.md). * The [Pen pressure response](/drawtab/core/pressure/pen-pressure-response.md) is the pen hardware's pressure behavior. It describes how a specific pen maps physical pressure to the logical pressure number sent to your computer. * A [Pen pressure curve](/drawtab/core/pressure/pen-pressure-curves.md) modifies or processes the pressure response of a pen. You can use it to solve or mitigate some pressure problems, or to achieve certain creative effects. * A [Pressure curve dead zone](/drawtab/core/pressure/pen-pressure-curves/pressure-curve-deadzone.md) uses a pressure curve to effectively increase the IAF. * The vast majority of drawing tablet pens are too sensitive to small changes in physical pressure near the IAF. This creates problems when [drawing at low physical pressure](/drawtab/core/pressure/drawing-low-pressure.md). You can address this with [Pen pressure curves](/drawtab/core/pressure/pen-pressure-curves.md) or **pressure smoothing**. * [Tilt affects pressure](/drawtab/core/pressure/tilt-affects-pressure.md). The pen is more sensitive when it is held perpendicular to the tablet surface. ## "Under pressure" video series If you'd prefer to watch, I built the "Under Pressure" video series on YouTube that goes deep into how pressure works. It explores all these concepts in great detail. {% embed url="" %} ## Relationship between the pen and the tablet * The pressure sensing mechanism is in the pen, not the tablet. * Tablets do play a role in processing pressure. They * Determine the number of pressure levels * Translate the pressure information from the pen into those levels * May process the pressure data before it is sent to the computer ## Units When dealing with the pressure (i.e. the force applied to the tip), the standard unit used is **gram force** abbreviated as **gf**. You may occasionally see this force described as **grams** and see the unit **g** used. This is technically incorrect, since grams are a unit of mass, not force. ## Disabling pressure Sometimes it is useful to disable pen pressure. For options, go here: [Disabling pen pressure](/drawtab/core/pressure/disable-pen-pressure.md). ## How EMR pens measure pressure There are two different techniques. The newer one uses a pressure sensor in the pen. More here: [EMR pressure detection](/drawtab/tech/emr/emr-pressure-detection.md). ## Notes * Pens, even of the same model, differ a little in their pressure sensitivity. * Pressure sensors are subject to wear. Over time, a pen may become less sensitive than it used to be. In practice, I have never noticed this in a meaningful way. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.sevenpens.com/drawtab/core/pressure.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.