Frequently Asked Questions

What image formats are supported?

MetricCanvas accepts any image format your browser can render — which in practice means JPEG, PNG, WebP, GIF, BMP, and TIFF. If your browser can display it, the tool can load it. SVG files are not currently supported as they are vector-based and render differently at different scales.

How accurate are the measurements?

Accuracy depends on two factors: the resolution of your image and the precision of your calibration clicks. The tool itself introduces no additional error — it calculates pixel distances using exact Euclidean geometry.

In practice, the main source of error is click placement. At high zoom, you can place clicks within 1–2 pixels of the intended point. At a typical image resolution of 300 dpi, 1 pixel corresponds to roughly 0.085 mm — more than enough precision for most practical tasks.

For maximum accuracy: use the highest resolution version of your image, zoom in as far as possible when clicking calibration and measurement points, and choose the longest possible calibration reference.

Does it work on mobile?

Yes. MetricCanvas has a mobile layout with a collapsible top menu for the sidebar controls. Touch input is supported for panning and placing measurement points. For precise measurements on small screens, we recommend zooming into the area of interest before clicking.

Are my images uploaded to a server?

No. MetricCanvas processes everything locally in your browser. Your images never leave your device. There is no server-side processing, no storage, and no account. This also means the tool works offline once the page is loaded.

How does calibration work exactly?

Calibration establishes a scale factor: the ratio between a real-world distance and the pixel distance between two points in the image. Specifically:

scale = real_world_distance ÷ √((x₂−x₁)² + (y₂−y₁)²)

Once you set the scale, every measurement uses the same factor. If you draw a line between two points that are d pixels apart, the tool reports d × scale as the real-world distance.

The calibration stays fixed until you change it. If your image contains objects at different distances from the camera (like a photograph with depth), the calibration is only valid for the plane containing your calibration reference. Distances in a different plane will be proportionally incorrect.

Can I use multiple units (metres and feet, for example)?

MetricCanvas stores the scale in relation to whatever unit you specify at calibration. If you calibrate in metres, all measurements report in metres. If you calibrate in centimetres, everything will be in centimetres. To convert, you can calibrate in the target unit — for example, enter 90 cm instead of 0.9 m to get measurements in centimetres directly.

Can I measure angles or areas?

MetricCanvas currently measures straight-line distances between two points. It does not have a built-in angle tool or an area calculator. For areas, you can measure each side of a rectangular room and multiply; for irregular shapes, you can measure multiple segments and apply external calculations.

What export formats are available?

Three formats are available from the Export panel:

PNG — full annotated canvas image with measurement lines and labels overlaid. Resolution matches your original image.

CSV — tabular data with columns for label, pixel distance, real-world distance, and unit. Compatible with Excel, Google Sheets, or any data tool.

TXT — plain-text list of all measurements, one per line.

Does the tool save my session between visits?

Yes. MetricCanvas saves your canvas state — including uploaded images, calibration, and all measurements — in your browser's local storage. When you reopen the tool in the same browser on the same device, your session will be restored automatically. Clearing your browser's site data will erase the saved session.

Can I work with multiple images at once?

Yes. Each image you upload becomes a separate layer on the infinite canvas. You can show or hide layers independently, reorder them, and pan freely between them. Each layer can have its own calibration, which is useful when working with drawings at different scales.

What browsers are supported?

MetricCanvas works in any modern browser: Chrome, Firefox, Safari, Edge, and their mobile equivalents. It requires JavaScript to be enabled. There is no plugin or extension needed. Internet Explorer is not supported.

Is MetricCanvas available in other languages?

Yes. The interface is available in English, Spanish, Catalan, German, French, Italian, Portuguese, Russian, and Japanese. Use the language switcher to change language. The URL updates to reflect the selected locale (for example, /es for Spanish or /de for German).

Can I measure from a PDF?

PDF files are not directly supported. However, you can take a screenshot of the PDF page, or export it as a high-resolution image from any PDF reader, and then upload that image to MetricCanvas. For best results, export at 300 dpi or higher.

Can I share my annotated image with someone?

Yes — use the PNG export to save the annotated canvas as an image, then share that file. You can also use the Share button in the sidebar to copy the tool's URL, which others can use to open their own session (sessions are not shared or synced between users).