What happens if the target length is shorter than the input?

The string is returned unchanged — padding is never applied when the input is already at or beyond the target length, which matches JavaScript behavior.

Can I use a multi-character fill string?

Yes. When you supply more than one character, the fill pattern repeats and is truncated to fit exactly, just like JavaScript's padStart() and padEnd().

What does "Both" padding mode do?

"Both" splits the required padding evenly between left and right. If the amount is odd, the extra character goes on the right side.

Is there a length limit?

The tool caps output at 10,000 characters to prevent browser slowdown. For longer strings, copy the generated JavaScript snippet and run it in your own environment.

Does this work with Unicode characters?

Yes — the tool uses JavaScript string methods, which handle Unicode code points correctly. Emoji or accented characters in the fill string will work as expected.

String Padding Tool

Pad any string to a target length using padStart (left), padEnd (right), or both sides at once.

Input

String

Target length

Fill character

Padding direction

Left (padStart) Right (padEnd) Both sides

Result

Padded string

Result will appear here

JavaScript equivalent

Summary

String Padding Tool lets you pad any string to a target total length by prepending or appending a fill character of your choice. It mirrors JavaScript's built-in padStart() and padEnd() methods and is useful for formatting fixed-width columns, aligning numeric output, building test fixtures, and generating padded identifiers.

How it works

Enter the string you want to pad in the input field.
Set the target total length (must be greater than the current string length).
Choose a fill character — default is a space, but any character works.
Select the padding direction: Left (padStart), Right (padEnd), or Both sides.
The padded result appears instantly below along with the equivalent JavaScript snippet.

Use cases

Format numbers into fixed-width columns for logs or reports.
Left-pad order IDs or invoice numbers with leading zeros.
Right-pad labels to align them in a monospace table.
Generate padded test fixtures for unit tests.
Produce padded binary or hex strings for low-level data formatting.
Quickly verify what padStart() / padEnd() would return without opening a browser console.

Frequently Asked Questions

Last updated: 2026-05-23 · Reviewed by Nham Vu