# Translation memory

Source: https://traduq.com/glossary/translation-memory · Updated October 14, 2026

A **translation memory** (TM) is a database of source sentences paired with their translations, which a [CAT tool](https://traduq.com/glossary/cat-tool) searches to suggest earlier translations when the same or similar text appears again.

## How a translation memory works

Each entry is a **translation unit**: one source segment, its translation, the two language codes and usually some metadata, such as who created it and when. Every time the translator confirms a segment, the CAT tool saves it to the TM. On the next job, each new segment is compared with the stored ones:

- an identical source comes back as a 100% match,
- a similar one as a [fuzzy match](https://traduq.com/glossary/fuzzy-match) with a score,
- anything below the lowest band counts as a new segment.

A TM stores sentences, not terms. Approved terminology lives in a separate [termbase](https://traduq.com/glossary/termbase).

## Why it matters for price and quality

Because reused sentences take less work, translators usually charge a share of the full rate for matched words. A [CAT analysis](https://traduq.com/glossary/cat-analysis) counts how many words fall in each band, which is how a TM lowers the cost of updates and repetitive texts. A TM also keeps wording consistent across documents, translators and years.

## File formats

Every CAT tool has its own TM format, such as Trados's .sdltm. To move a memory between tools, you export it as [TMX](https://traduq.com/glossary/tmx), the standard exchange format. Our post on [XLIFF, TMX and TBX](https://traduq.com/blog/xliff-tmx-tbx-formats-explained) explains how the formats fit together.

## Example

Last year you translated "Press the red button to stop the machine." and saved it to your TM. This year's manual says "Press the green button to stop the machine." Your CAT tool shows last year's translation as a fuzzy match of about 93%, highlights the changed word, and you only replace the colour.

A TM is only as good as what goes into it. Duplicates, empty units and conflicting translations produce bad suggestions; see [how to clean a TMX file](https://traduq.com/blog/clean-tmx-translation-memory). TraduQ's free [TM cleaner](https://traduq.com/tools/tm-cleaner), [TMX editor](https://traduq.com/tools/tmx-editor) and [TMX merge](https://traduq.com/tools/tmx-merge) work in your browser, and your memory is never uploaded.

## Try it

- [TM cleaner](https://traduq.com/tools/tm-cleaner) — Find and remove duplicates, empty and broken segments in a TMX.
- [TMX editor](https://traduq.com/tools/tmx-editor) — Edit target segments with memoQ-style tags, delete units and save a TMX.
- [Merge TMX files](https://traduq.com/tools/tmx-merge) — Combine several TMX files into one, without duplicates.
- [Open SDLTM files](https://traduq.com/tools/sdltm-converter) — Read Trados memories without Trados and save them as TMX, Excel or CSV.

## Related terms

- [TMX](https://traduq.com/glossary/tmx)
- [Fuzzy match](https://traduq.com/glossary/fuzzy-match)
- [CAT tool](https://traduq.com/glossary/cat-tool)
- [CAT analysis](https://traduq.com/glossary/cat-analysis)

## Related guides

- [Best memoQ Alternatives in 2026 (Free, Mac and Cloud)](https://traduq.com/blog/memoq-alternatives) — Looking for a memoQ alternative? Trados, Phrase TMS, Wordfast, CafeTran, OmegaT, MateCat and Smartcat compared: who each suits, price model, key difference.
- [How to Open an SDLTM File Without Trados (Free)](https://traduq.com/blog/open-sdltm-without-trados) — Open a Trados Studio .sdltm translation memory without a licence and convert it to TMX, Excel or CSV in your browser. Step by step, plus other ways.
- [Best Trados Alternatives in 2026 for Freelance Translators](https://traduq.com/blog/trados-alternatives) — Trados Studio alternatives for freelancers in 2026: memoQ, Wordfast Pro, Phrase TMS, CafeTran, OmegaT and MateCat on price, Mac and Trados files.