Pen Pressure Test

How to test pen pressure

1. On Windows with a drawing tablet, turn on Windows Ink in the tablet driver first, for example Use Windows Ink in Wacom Tablet Properties. Browsers get pen pressure through it.
2. Draw in the black area with the pen tip, pressing lightly and then harder. The line should get thicker, and Pressure should rise from near 0 toward 1.
3. Watch Pressure levels seen: it counts the different pressure values the browser has received and should keep rising as you vary the pressure. If Pressure stays at 0.500 while you draw, no pressure data is reaching the browser.
4. Tilt the pen, then hold it just above the surface. Tilt X / Y changes on a pen that senses tilt, Contact shows Hovering on pens and devices that report hover, and Reported so far lists each pen feature the browser has passed on.
5. Press each pen button, then turn the pen over and draw with the eraser if it has one. Buttons lists what is held, and the eraser erases the line.
6. Press Clear to wipe the drawing and start the counts again.

What are pen pressure levels?

Pen pressure levels are the number of steps a pen or drawing tablet reports between its lightest and its firmest press, such as 4,096 or 8,192. Browsers scale every pen's pressure to a value from 0 to 1, so a web page can show the pressure it receives but cannot read the number of levels the hardware advertises.

Why pen pressure is not working

• Pressure stays at 0.500 while you draw: the browser gets the pen without pressure data. Anything that sends no pressure reports 0.5 while the tip is down, as a default rather than a reading of how hard you press.
• Pointer type shows Mouse: the browser is getting the pen as a mouse. On Windows, turn on Windows Ink in the driver, for example Use Windows Ink in Wacom Tablet Properties, then restart the browser.
• Pointer type shows Touch for a pen that senses pressure: some browsers and drivers report a pen as a touch. If another browser shows Pen, the first browser is the cause, not the pen.
• Pressure works in a drawing app but not here: on Windows, some drawing apps can read the tablet another way through their own settings, while browsers use Windows Ink. Some drivers also set Windows Ink for each app separately.
• The pen has no pressure sensor: Apple Pencil (USB-C) senses tilt but not pressure, so Pressure does not follow how hard you press with it, and that is not a fault. A stylus with a soft rubber or mesh tip works like a finger, so Pointer type shows Touch; check it with the Touch Screen Test.
• Pressure never reaches 1, or light strokes do not register: your pen driver’s settings can change the pressure your browser receives, so check its pressure settings. Lowest / highest shows the range you reached.
• Try another browser, and update the tablet driver: if pressure changes in the other browser, the pen works and the first browser or its settings are the cause.

What the pen read-outs mean

These are the ranges Pointer Events define. When the hardware or the browser has no data for a sensor, the browser sends the default in the last column, so a default can mean a missing sensor or a pen held exactly that way. Altitude / azimuth is the same pen angle as Tilt X / Y in another form, not extra sensor data: Chrome, for example, works it out from tilt, which it rounds to whole degrees. Where the browser does not report it, the read-out shows Not reported by this browser, and updating the browser may add it; the Browser Test shows which version you have.

What this test can detect

• Whether pen pressure reaches the browser at all: Pressure changes as you press, instead of staying at 0.500.
• A pressure range that ends early, such as a pen that never passes 0.700 or misses light strokes, shown under Lowest / highest.
• Tilt, twist and tangential pressure the pen passes on, as values that move away from 0° or 0.00.
• Hover: Contact shows Hovering while the tip is just above the surface, on pens, devices and browsers that report it.
• The eraser and each pen button, listed under Buttons while held.
• Drop-outs: gaps in a line you drew without lifting the pen.

How it works

The page reads Pointer Events in the drawing area, with the in-between positions a browser groups into one event where it lists them. While the tip is down, each position adds a line from 1 px wide at pressure 0 to 16 px at pressure 1; the eraser paints black, 6 px to 36 px wide.

Pressure levels seen counts the different values above 0 reported while pressed, for each pointer type, up to 10,000. Pressure counts as changing at 5 values, and as not changing once one value repeats for 20 pressed samples, or on any mouse press.