Why 4 spaces specifically?

It's the most common indentation width in style guides that use spaces. Only exact runs of 4 consecutive spaces are converted; 2-space or irregular indentation won't match cleanly.

Does it affect spaces in the middle of a line, not just indentation?

Yes, the replacement isn't limited to leading whitespace; any run of exactly 4 consecutive spaces anywhere in the text is converted.

Is the width configurable?

Yes. The pattern is built from the width you choose and defaults to 4, so 2-space or 8-space indentation converts just as readily once the matching value is set.

Spaces to Tabs Online - Space to Tab Indentation

Overview

Introduction

Switching a codebase or config file's indentation style from spaces to tabs means precisely converting every indentation level.

This tool converts every 4-space run to a tab.

What Is Spaces to Tabs?

A converter that replaces every run of exactly 4 consecutive space characters with one tab character.

It runs entirely client-side as part of this site's String Tools collection, so nothing you paste is ever uploaded to a server.

How Spaces to Tabs Works

A regex matching 4 consecutive spaces is replaced globally with a tab character.

The transformation happens synchronously in JavaScript the moment you type, with no network round trip involved.

When To Use Spaces to Tabs

Use it when converting space-indented source code or config files to tab indentation.

It's a fast way to get the answer without opening a code editor, a REPL, or writing a one-off script just to check.

Often used alongside Tabs to Spaces and Whitespace Remover.

Features

Advantages

Simple, predictable conversion for standard 4-space indentation.
Builds its pattern from the width you specify, so the tool is not locked to a single indentation convention.
Converts a whole file in one pass, keeping the relative indentation depth of every line intact.

Limitations

Only matches exact 4-space runs; 2-space or inconsistent indentation won't convert as expected.
Doesn't distinguish leading indentation from spaces elsewhere in a line.

Examples

Converting indented code

Input

    indented
    code

Output

	indented
	code

Each 4-space indent becomes a single tab character.

Best Practices & Notes

Best Practices

Verify your source actually uses consistent 4-space indentation before converting, or the result may be uneven.
Convert the entire file rather than a fragment, so the indentation stays consistent throughout it.
Set your editor's tab width to the space count you converted from, so the file looks unchanged afterwards.

Developer Notes

The replacement regex is built dynamically as `{width} spaces`, defaulting to 4, so it matches runs of exactly that many consecutive spaces rather than any arbitrary run length.

Spaces to Tabs Use Cases

Converting a space-indented file to tab indentation
Normalizing indentation style across a codebase
Preparing code for a style guide that requires tabs

Common Mistakes

Running this on 2-space-indented code, which won't match the 4-space pattern.
Converting a file that already mixes tabs and spaces, which leaves the mixture in place and can make the indentation worse rather than better.

Tips

Use Convert Tabs to Spaces to reverse this operation.
Runs anywhere on a line are converted, not only leading indentation, so check aligned comments and tables after running it.

Spaces to Tabs