Pen Pressure Test
Draw on the canvas with your drawing tablet, pen display or stylus to see whether the browser receives pressure, tilt and twist from it. Strokes get thicker as you press harder, and a live graph shows exactly how pressure changes along each stroke.
How to use the Pen Pressure Test
- Connect your tablet or pick up your stylus and make sure its driver is running.
- Draw on the canvas, pressing lightly and then harder. The stroke should get thicker as you press.
- Watch the readouts: pressure, tilt and twist update live, and the graph shows pressure over time.
- Check the status line: it tells you whether real pressure data is arriving or only a fixed value.
- Adjust the curve and size to try soft or firm response, then download the drawing or clear the canvas.
What each value means
| Value | Range | What it measures |
|---|---|---|
| Pressure | 0 to 1 | How hard the pen tip presses. 0 = hovering, 1 = maximum. A mouse reports 0.5 while a button is held. |
| Tilt X | -90° to 90° | Angle between the pen and the vertical, leaning left (negative) or right (positive). |
| Tilt Y | -90° to 90° | Angle leaning towards you (positive) or away from you (negative). |
| Altitude / azimuth | 0° to 90° / 0° to 360° | The same tilt expressed as the angle above the surface and the compass direction of the lean. |
| Twist | 0° to 359° | Rotation of the pen around its own axis (barrel rotation), only on pens with a rotation sensor. |
| Tangential pressure | -1 to 1 | Barrel pressure from a finger wheel, as on an airbrush pen. 0 on most pens. |
| Report rate | Hz | How many pen samples per second the browser receives while drawing, including coalesced events. |
Pressure not working? Fixes by system
- Windows with Wacom, Huion, XP-Pen or Gaomon: open the tablet driver, enable Windows Ink for the pen, apply, then restart the browser. If pressure still shows 0.5, reinstall the latest driver and reboot.
- Windows with Surface Pen or pen laptops: pressure works out of the box in Edge, Chrome and Firefox; update the pen firmware and Windows if it does not.
- macOS: install the tablet maker's driver and grant it Accessibility and Input Monitoring permission in System Settings → Privacy & Security.
- iPad with Apple Pencil: Safari and other iPad browsers report pressure and tilt. Turn off Scribble if it interferes with drawing.
- Android: stylus devices such as Galaxy S Pen report pressure in Chrome. Passive capacitive styluses do not measure pressure.
- Linux: make sure the tablet is handled by the libinput or wacom driver; Chrome and Firefox read pressure on both X11 and Wayland.
Pressure curves
The curve setting changes how pressure maps to stroke width: Linear uses the raw value, Soft (pressure0.6) gives thicker lines with a light touch, and Firm (pressure1.8) needs more force for thick lines. The readouts and graph always show the raw pressure the browser receives.
Frequently asked questions
How does this pen pressure test work?
Modern browsers expose stylus data through the Pointer Events standard. Each pen event carries a pressure value from 0 to 1, tiltX and tiltY in degrees, twist in degrees and, on newer browsers, altitude and azimuth angles. The page reads these values as you draw and shows them live; nothing is sent anywhere.
Why does it always show 0.5 pressure?
A pressure of exactly 0.5 while drawing means the browser is not receiving pressure from the device and reports the default value for a pressed button. This happens with a mouse, and with a tablet whose driver is acting as a mouse. On Windows, enable Windows Ink in the tablet driver (Wacom, Huion, XP-Pen) and make sure the driver is installed and running, then reload the page.
My tablet works in drawing apps but not in the browser. What can I do?
Drawing apps often use the WinTab API, while browsers use Windows Ink. Turn on Windows Ink (or 'Use Windows Ink') in your tablet's driver settings, restart the browser, and try again. On Linux, Chrome and Firefox support pressure through X11 or Wayland input drivers. On macOS pressure works in Safari, Chrome and Firefox with the vendor driver installed.
Does the Apple Pencil or Surface Pen work?
Yes. Apple Pencil on iPad in Safari reports pressure and tilt, and Surface Pen and other Windows Ink pens report pressure, tilt and often eraser. Finger touch usually reports a fixed pressure or 0, because most touchscreens do not measure force.
What does pressure levels detected mean?
It is the number of distinct pressure values the browser delivered during your strokes. Tablets advertise 2048, 4096 or 8192 hardware levels, but browsers may round values and you rarely hit every level, so this count shows how smooth the data you actually get is, not the hardware specification.
What are tilt and twist?
Tilt X and tilt Y are the angles of the pen from vertical along the x and y axes, from -90 to 90 degrees. Twist is the rotation of the pen around its own axis from 0 to 359 degrees, supported by a few pens such as the Wacom Art Pen. If your pen has no sensor for a value, the browser reports 0.