Convert MDB to DuckDB
Upload a .mdb or .accdb or .mde file and get back a DuckDB file. Types are preserved rather than flattened to text. Free, no registration, up to 10MB.
Click to upload or drag and drop
CSV, Excel, SQLite, SQL, DBF (max 10 MB)
How your data is typed in DuckDB
Generated from the converter's own DuckDB type mapping — this is what it actually emits, not an example.
| Your data | DuckDB type |
|---|---|
| Whole number | BIGINT |
| Decimal (money) | DECIMAL(10,2) |
| Floating point | DOUBLE |
| True / false | BOOLEAN |
| Date | DATE |
| Date and time | TIMESTAMP |
| Short text | VARCHAR |
| Long text | VARCHAR |
| Binary data | BLOB |
Working from an .mdb file
An .mdb file is Jet 4, the engine Access used up to 2003. It is the format most likely to be sitting on a share drive with no copy of Access left in the building to open it - which is the situation this converter exists for.
- →Jet 4 caps a database at 2 GB and a table at 255 columns, which is why an .mdb that has outgrown its purpose is usually a migration rather than a rewrite.
- →There is no companion file to hunt for. A .ldb sitting beside the database is only a lock file from whoever last had it open, and nothing in it is needed - upload the .mdb on its own.
- →Every table is read into memory in one pass before anything is written out, which is affordable only because the free upload is capped at 10 MB; a full-size Jet database would not be.
Decimals and text in the .duckdb file
DuckDB takes the source's declared types more nearly unchanged than any other target here, which makes the two places where it cannot the things worth reading: the width of a decimal, and the length of a string.
- →DECIMAL tops out at 38 digits, so a wider source column is clamped rather than refused: an Oracle NUMBER(50,10) is created here as DECIMAL(38,10), and the scale is never allowed to grow past the precision holding it.
- →A decimal that declared no scale gets six places for its fraction rather than none, inside that same rule: a source precision of 10 becomes DECIMAL(10,6), one of 5 becomes DECIMAL(5,5), and one that declared no precision either becomes DECIMAL(18,6).
- →Strings become VARCHAR with no length attached to them. DuckDB's VARCHAR is unbounded, so no column has to be sized in advance and no row can be turned away for being longer than the column it goes in.
Reading MDB
- →Dates are exported in ISO form, avoiding the ambiguous 12/02/21 that Access tools produce by default.
- →NULL and the empty string stay distinct.
- →Access can hold dates outside the range it can represent. Those become NULL and the conversion tells you, rather than dropping them silently.
- →Requires mdbtools on the server; if it is unavailable you get a clear error rather than a partial conversion.
Writing DuckDB
- →A real .duckdb file, not a script — open it straight away with the DuckDB CLI.
- →DuckDB has genuine DECIMAL and BOOLEAN types, so nothing is flattened on the way in.
What you get
A ZIP containing database.duckdb. If anything about your data needed a judgement call, a _warnings.txt explains it.
Questions
- Is converting MDB to DuckDB free?
- Yes. Files up to 10MB convert free with no account. There is a limit of five conversions per day per IP address.
- Will my MDB data keep its types in DuckDB?
- Yes — that is the point. Whole numbers, decimals, dates and booleans are mapped to real DuckDB types rather than everything becoming text. The mapping table above shows exactly what you get.
- Do you store my file?
- No. The file is written to a temporary directory, converted, and the directory is deleted as soon as your download has been sent.