Stylus Pressure Tester
Draw on the paper above. Stroke width and ink darkness follow the pressure your stylus reports.
Pressure and tilt are read live from the browser Pointer Events API on your own device; your drawing never leaves this page.
How it works
仕組みDraw on the canvas below to see exactly what your stylus reports to the browser: live pressure from 0.00 to 1.00, the peak you reached, the pointer type, and pen tilt when your hardware supports it. Stroke width and ink darkness follow the pressure signal in real time, so a faulty pressure curve, dead nib, or driver problem shows up immediately as flat, lifeless lines. Pressure data comes straight from your pen, screen, and driver working together, so the only way to test that chain is to draw on your own device.
A constant 0.50 while pressing means the browser is treating your input as a plain mouse; the Pointer Events spec assigns mice a fixed 0.5 when a button is down. That happens with non-pressure styluses, missing pen drivers, or browsers that don’t pass pen data through. An active stylus (Apple Pencil, S Pen, Surface Pen, Wacom) should show smoothly varying values.
Usually not. Many pens require a very firm press to hit full scale, and some drivers cap the reported maximum below 1.00 by design or by pressure-curve settings. If your peak lands around 0.8-0.9 with a hard press and the low end responds smoothly, the pen is healthy; a jumpy or stepped reading is the real warning sign.
Tilt (tiltX/tiltY, in degrees from vertical) is a separate sensor from pressure, and plenty of otherwise good pens simply don’t have it: many budget styluses and older Apple Pencil setups in browsers report 0 or nothing. If your pen advertises tilt but shows none here, check the driver, and note that some browsers only expose tilt for certain pen protocols.