BYTETOOLS

CSV to Fixed-Width Converter

Convert CSV to a fixed-width flat file online. Auto-fitted column widths, per-column alignment and padding, plus a copy-ready layout specification.

Drop a .csv file here or click to browse

What is the CSV to Fixed-Width Converter?

The ByteTools CSV to Fixed-Width Converter turns delimited data into the column-aligned flat files that banking, payroll, EDI and mainframe systems still expect.

  • Column widths auto-fitted to the longest value
  • Per-column width and left/right alignment
  • Custom padding character and inter-column gap
  • Truncate or keep values longer than their field
  • Layout spec with start, end, length and total record length
  • Everything runs locally — no upload, no sign-up

How to use the CSV to Fixed-Width Converter

  1. 1

    Paste your delimited data, or drop a .csv file into the drop zone.

  2. 2

    Pick the delimiter and say whether the first row is a header.

  3. 3

    Adjust each column's width and alignment, or click Auto-fit to content.

  4. 4

    Set the padding character, the gap between columns and how to treat over-long values.

  5. 5

    Copy or download the fixed-width file and its layout specification.

About the CSV to Fixed-Width Converter

The ByteTools CSV to Fixed-Width Converter turns delimited data into the column-aligned flat files that banking, payroll, EDI and mainframe systems still expect. Paste your CSV and each column's width is auto-fitted to its longest value, with numeric columns right-aligned and text columns left-aligned by default.

Every column is then yours to adjust: set an exact width, switch the alignment, change the padding character, choose the gap between columns and decide whether over-long values are truncated to the field or allowed to run on. The output updates as you go, in a monospaced box where the alignment is easy to check.

Alongside the file you get a layout specification listing each column's start position, end position, length and alignment, plus the total record length — the document the receiving system's integration team will ask you for. It is the exact inverse of our fixed-width to CSV tool, and like that one it runs entirely in your browser.

Frequently asked questions

What is a fixed-width file?

A text file where every field occupies the same character positions on every line, padded with spaces instead of separated by commas. Banking, payroll and mainframe interfaces still use them because a record can be read by position alone.

How do I choose the right column widths?

Start with Auto-fit to content, which sizes each column to its longest value, then widen the fields the receiving system specifies. If your data will grow, leave headroom — truncation is silent by design in fixed-width formats.

What happens if a value is longer than its column?

You decide. 'Truncate to the width' cuts it so the record length stays exact, which is what most interfaces require. 'Keep in full' preserves the data but pushes every later field out of position on that line.

Why would I change the padding character?

Some legacy formats pad numeric fields with zeros rather than spaces, so an amount is written 0000123456. Set the pad character to 0 and right-align that column to produce it.

What is the layout specification for?

It is the contract for the file: the start and end position, length and alignment of every field, plus the total record length. Send it with the file so the receiving system knows how to slice each line.

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