# Pen Pressure Test

> Test pen pressure, stylus tilt, and twist online. Free drawing tablet pressure test with real-time pressure curves and estimated levels. Nothing uploaded.

- URL: https://bytescope.dev/en/pen-pressure-test/
- Locale: en · Also: [ja](https://bytescope.dev/ja/pen-pressure-test.md) · [zh-Hant](https://bytescope.dev/zh-Hant/pen-pressure-test.md)
- Runs: Nothing is uploaded. Pen and pointer events are processed locally in this tab.
- Requires: Any modern browser (Chrome, Edge, Firefox, Safari), desktop and mobile.
- Updated: 2026-09-08

## What it does

Test your stylus and drawing tablet in this tab without installing drivers or software. Draw on the canvas to run a live pen pressure test with real-time pressure curves, tilt angles, and barrel twist readouts. Whether you are troubleshooting why pen pressure is not working or verifying a new stylus, this page shows exactly what your browser receives from Pointer Events.

### Normalized values, not raw hardware levels

Web browsers report stylus pressure as a normalized floating-point number between 0.0 and 1.0 via the Pointer Events API (`pointerdown` and `pointermove`), rather than raw hardware analog-to-digital levels. Devices without pressure sensitivity (like mice or standard touchscreens) report a fixed fallback value of 0.5 according to the W3C specification. This page detects fixed-pressure inputs and clearly identifies them instead of displaying misleading pressure readings.

### Estimated pressure levels

Drawing tablet specifications often advertise 2048, 4096, or 8192 pressure levels. Because browsers do not expose the hardware specification directly, this tool analyzes the smallest non-zero step sizes between observed distinct pressure values to compute an estimated level count. Draw varied strokes from light touches to firm pressure to collect enough samples for an accurate estimate.

### Stylus tilt and barrel twist

In addition to pressure, compatible styluses (such as Apple Pencil, Wacom Pro Pen, or Microsoft Surface Pen) report tilt angles (tiltX, tiltY, altitudeAngle, azimuthAngle) and barrel twist rotation. The readout panel displays these values in real time so you can run a complete stylus tilt test and verify all dimensions of pen input.

### Privacy by design

All drawing input, pointer events, and pressure calculations are processed entirely on your device inside your browser tab. No coordinates, stroke data, or device telemetry are ever uploaded or transmitted to any server.

## Limits

Does not show raw hardware pressure levels (the browser normalises to 0–1) and does not fix driver problems.

## FAQ

### Why is pen pressure not working on my drawing tablet?

If pressure is not detected, check that your tablet driver (such as Wacom Tablet Properties or manufacturer utility) is installed and Windows Ink (or stylus support on macOS) is enabled. Browsers rely on the operating system's pen API to receive pressure data.

### Why does the stroke show 0.5 pressure with a mouse?

According to the W3C Pointer Events specification, devices that do not support pressure report a constant value of 0.5 for active buttons. This tool flags non-pressure inputs with an honest warning banner rather than mistaking 0.5 for stylus pressure.

### How accurate is the estimated pressure levels number?

The level count is a mathematical estimate inferred from the smallest step size between unique pressure readings observed during your drawing session. Because it is calculated from browser event quantization rather than read from hardware firmware, draw smooth slow strokes across the full pressure range to improve estimation accuracy.

### Does this online pen pressure test work with Wacom, iPad, and Surface?

Yes. Any device and stylus that emits standard Pointer Events with pen pointerType — including Wacom tablets, XP-Pen, Huion, Apple Pencil on iPadOS browsers, and Microsoft Surface Pens — is supported directly in the browser.

### Are my drawings or pressure data uploaded anywhere?

No. All pointer event processing, canvas rendering, and statistical analyses run locally in client-side JavaScript. No drawing data or device details leave your machine.

## Related tools

- [Touch Test](https://bytescope.dev/en/touch-test.md) — Multi-touch trails, browser event sample rate, and dead-spot grid.
- [Display & Monitor Test](https://bytescope.dev/en/screen-test.md) — Dead pixels, backlight bleed, banding, gamma, ghosting, refresh rate.