Convert ACCDB 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 .accdb file
An .accdb file uses ACE, the engine that replaced Jet from Access 2007 onward. It adds attachment and multi-value fields that have no equivalent in any relational target, so it is worth knowing what happens to them before you convert.
- →Ordinary tables and columns convert exactly as they do from .mdb - the reader is the same one.
- →Attachment and multi-value fields have no relational equivalent and no type of their own here: they fall back to text columns rather than stopping the conversion.
- →ACE supports a genuine database password, and there is no way to supply one to the reader - remove the password in Access before uploading.
- →The recognised Access extensions are .mdb, .accdb and the compiled .mde. A compiled .accde front-end is not among them, so upload the .accdb it was built from.
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 ACCDB
- →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 ACCDB 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 ACCDB 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.