ODT to BMP Converter

ODT to BMP Converter

An ODT is an editable OpenDocument Text file — the native document of LibreOffice Writer and Apache OpenOffice Writer, and an export target of Google Docs. BMP is the Windows device-independent bitmap: a header, an optional colour table, and rows of pixels. Converting between them rasterizes each page of the document into a flat picture, one BMP per page. People reach for it when a legacy Windows application, an embedded display, a label printer or an imaging pipeline will only accept a bitmap. One thing worth knowing before you start: what this tool writes is not always the raw 24-bit bitmap people imagine — the Quality Preset picks between three genuinely different BMP encodings, and the table further down shows what each one actually produces.

ODT Format at a Glance

BMP Format at a Glance

What Each Quality Preset Actually Writes

The BMP list offers only three entries — High, Medium and Low — and the picker opens on High. The other four presets that appear on formats like JPG and AVIF are deliberately hidden here, as are the "Target file size" and "Image Quality (%)" controls, because a bitmap has no continuous quality dial to turn. Measured on one US Letter page of body text, a footnote and a small table, rendered at the default 300 DPI (2,550 × 3,300 pixels):

Two things fall out of that table that are worth planning around. First, High is roughly 64× larger than the palette presets, because it is the only one the BMP format lets you store without compression. Second, Low is not reliably smaller than Medium — on this text page it came out marginally larger at every DPI tested, because dithering an image down to 86 colours scatters more short runs for the run-length encoder to trip over, and the V5 header adds a few dozen bytes on top. Choose Low for a palette constraint, not for file size.

How to Convert ODT to BMP

1. Upload Your ODT File: Drag your .odt onto the page or click "+ Add Files" to browse. Several documents can be queued and converted with the same settings in one batch.
2. Set Conversion Quality (DPI): This is the render resolution for the page rather than a compression setting, and on an uncompressed bitmap it drives file size directly. The choices are 72, 96, 150, 200, 300 (preselected), 400, 600 and 1200 DPI.
3. Pick a Quality Preset and Background Colour: Under Image Compression choose High, Medium or Low as described above. Under Image Transparency, the Colour dropdown fills the page background — White is preselected, and 24 other named colours are available.
4. Convert and Download: Click Convert. A single-page document downloads as one .bmp; a longer document returns one BMP per page with a "Download All (Zip)" button to collect them. No sign-up, no watermark.

How DPI Multiplies an Uncompressed Bitmap

At the High preset the arithmetic is exact — two bytes per pixel, and the pixel count grows with the square of the DPI. The same US Letter page measured across the ladder:

If the destination system only needs to display the page on screen, 150 DPI at the High preset is usually the sweet spot; going to 600 DPI multiplies the bytes by sixteen for detail a screen cannot show.

Frequently Asked Questions

Does a multi-page ODT become one BMP or many?

Many. A BMP file holds exactly one image, so each page of the document is rendered separately: a one-page ODT downloads as a single .bmp, and anything longer returns one bitmap per page in document order, with a "Download All (Zip)" button to fetch the set. There is no multi-page bitmap format to fall back on. If you want every page held together in a single file, convert to ODT to PDF; for a genuine multi-page raster container, ODT to TIFF is the closer relative.

Is the BMP this tool produces uncompressed 24-bit colour?

No, and it is a common misconception worth correcting. The High preset writes 16 bits per pixel — five bits each for red, green and blue — which is uncompressed but half the size of a 24-bit bitmap and quantised to 32,768 possible colours rather than 16.7 million. The Medium and Low presets are palette bitmaps that are compressed, using the BI_RLE8 run-length scheme. If a downstream system specifically requires 24-bit BI_RGB data, none of the three presets here matches that exactly, and you are better off exporting ODT to PNG and converting it with a tool that lets you name the bit depth.

Why is my BMP so much larger than a PNG of the same page?

Because the High preset stores every pixel literally while PNG applies lossless compression that is extremely effective on text. On the measured page, the High-preset BMP was 16.8 MB against 196 KB for a lossless PNG of the identical render — roughly 85× larger for pixel-identical content. BMP simply has no compression mode available above 8 bits per pixel, since Microsoft only defines run-length encoding for 4- and 8-bit bitmaps. Unless something downstream truly demands a bitmap, ODT to PNG is the better lossless choice.

Why did the Low preset give me a bigger file than Medium?

Because file size at these presets is decided by how well run-length encoding compresses, not by how many colours are in the palette. Dropping from 256 to 86 colours forces heavier Floyd–Steinberg dithering, which breaks long identical runs into short alternating ones — precisely the pattern BI_RLE8 handles worst. Measured at 72, 150, 300 and 600 DPI on a text page, Low came out a few percent larger than Medium every time. Medium is the preset to pick when size is what you care about.

Can I still select or search the text after converting to BMP?

No. Rasterizing paints the glyphs into a fixed pixel grid, so there is no text layer left to select, copy, search or reflow — the same is true of any image format. Getting the words back would mean running OCR over the bitmap. Keep the original .odt if you may need to edit again, convert to ODT to DOCX to continue editing in Word, or to ODT to PDF for a fixed copy that still has a searchable text layer.

What does the "Conversion Quality" dropdown actually change?

It sets the DPI at which the document's pages are rasterized, so it changes the pixel dimensions of the output rather than any compression parameter. A US Letter page comes out 612 × 792 at 72 DPI and 2,550 × 3,300 at the preselected 300 DPI; A4 comes out 2,480 × 3,508 at 300 DPI. Everything downstream — sharpness, legibility of small type, and on an uncompressed bitmap the file size — follows from that single choice, which is why it is the first setting to think about.

Can the background be transparent instead of white?

Not in these outputs. A rendered word-processing page is opaque to begin with, and none of the three BMP presets here writes an alpha channel, so the Image Transparency group's Colour dropdown decides what solid colour fills the page area. White is preselected because it matches a printed sheet; 24 other named colours are available if the bitmap will sit against a coloured background. For a page image that genuinely carries transparency, use ODT to PNG.

Is the upload private, and is there a size limit?

Your file is uploaded over an encrypted connection, converted on our servers — LibreOffice lays the document out, each page is rasterized at your chosen DPI, and the pages are encoded as bitmaps — and then deleted automatically after a few hours. No sign-up, no watermark, and nothing is shared or made public. There is no fixed page-count cap, but bear the arithmetic above in mind: a 20-page document at 600 DPI on the High preset is well over a gigabyte of bitmaps, so lower the DPI or pick Medium before converting anything long.