BMP to SVG converter
Choose a BMP and get an SVG of vector shapes traced from its pixels: one colour for cutting and engraving, or up to twelve flat colours for artwork.
Free, no account. The file is read by code running in your browser. It is not uploaded, and nothing about it is stored.
If the page says it cannot read your BMP, it is one of the rarer kinds browsers do not decode. Save it again as a 24-bit BMP or a PNG.
How to convert a BMP to SVG
- Choose your BMP file or drop it on the box.
- Pick black and white for a single outline, or colours for flat artwork.
- Move the threshold, or the number of colours, until the preview on the right matches the bitmap on the left.
- Download the SVG. It takes the name of your BMP.
What a BMP file is
BMP is the bitmap format Windows has used since the 1980s. It usually stores every pixel as it is, with no compression at all: three bytes for each pixel in the common 24-bit kind, with each row padded to a multiple of four bytes. That makes the sums easy. A 1,000 × 1,000 pixel 24-bit BMP is 3,000,054 bytes, the 54 being the header. The same picture as a PNG might be a twentieth of that.
BMPs turn up where simple software writes pictures: Windows Paint, older scanners, screenshots from instruments and machine controllers, embroidery and sign software, and games that keep their artwork in the open. There are also smaller kinds with a palette of 2, 16 or 256 colours. The 2-colour kind, which Paint calls a monochrome bitmap, is one bit for each pixel.
Why BMPs trace well, and where they do not
Because nothing has been thrown away to save space, a BMP has none of the speckle that JPG compression leaves round edges. What the tracer sees is what was drawn. A monochrome bitmap is the ideal case for a black and white trace: every pixel is already ink or paper, and the threshold hardly matters.
The weakness is the opposite one. Drawings made in Paint with the pencil or the fill bucket have hard, stair-stepped edges with no soft pixels along them, so there is nothing to tell the tracer where between two pixels the true edge runs. Turn the smoothing up a step or two and the stairs become clean slants and curves. Scans saved as BMP behave like any scan: use black and white, and raise “Ignore specks under” to drop dust.
Transparency, size and what the browser reads
- Transparency: most BMP files have none. A drawing on a white background stays on white, and in colour mode that white is written as a rectangle the size of the picture behind everything else; delete it afterwards, or trace in black and white. The few 32-bit BMPs that carry transparency are read as your browser reads them, and see-through areas count as white paper.
- Size: a BMP of any size can be chosen. One over 2,000 pixels on its longer side is scaled down to that before tracing.
- Kinds that open: the picture is decoded by your browser. Chrome, Edge, Firefox and Safari all read the ordinary uncompressed kinds: 1, 4, 8, 24 and 32 bits for each pixel. Rarer ones may be refused, and the page then says it could not read the file.
Questions
Is the SVG just my bitmap wrapped in an SVG file?
No. Nothing of the BMP is put in the SVG. The file holds paths made of straight lines and Bézier curves that follow the edges of the bitmap’s areas of colour, so it can be scaled, cut and engraved. In colour mode there is also one plain rectangle, for the background colour.
My BMP is huge. Will it be slow?
The size in megabytes comes from the lack of compression, not from extra detail. A 3 MB BMP is only a 1,000 pixel square picture, and it traces in a second or two on most devices.
Why do I get a big rectangle round my drawing in colour mode?
That is the bitmap’s background. In colour mode the colour that covers the most area, usually the white behind the drawing, is written as a rectangle the size of the picture. In a vector editor, select it and delete it. In black and white mode the background is paper and is not traced.
Can I convert a 1-bit BMP from a scanner?
Yes, and it is the easiest kind: black and white mode gives one outline for every black area. If the scan is dotted with dust, raise “Ignore specks under” until the dots go.