Left-pad Integers
Pad integers on the left up to a fixed width. Runs entirely in your browser, so your data never leaves your device.
0 chars · 0 lines
Output
The result appears here as you type.
How to use Left-pad Integers
- 1. Paste your integers. Enter the integers you want padded, one per line or separated by whitespace, regardless of how many digits each already has.
- 2. Set the target width. Enter Target width to define how many characters each integer should occupy after padding, such as 5 to turn 42 into a five-character string.
- 3. Choose the fill string. Enter Fill string to control what character fills the gap, such as 0 for zero-padding or a space for visual alignment.
- 4. Copy the padded integers. Copy the resulting list, where every integer has been extended on the left to match your target width using the chosen fill.
When to use Left-pad Integers
Left-pad Integers extends each number with a fill character on the left until it reaches a fixed width, most commonly for zero-padding. Use Left-pad Integers whenever numbers of varying length need to line up as fixed-width strings, like invoice numbers or file names.
- Formatting invoice or order numbers. Your invoicing system expects five-digit order numbers like 00042, but your data has plain integers of varying length. Zero-pad the whole batch to match.
- Naming sequential files consistently. You are generating file names like frame001.png through frame999.png and need the numeric part padded to a fixed width so files sort correctly.
- Matching a fixed-width legacy format. An older system expects numeric fields to always be a specific character width, and your export has integers of inconsistent length that need padding before import.
- Aligning a numeric column visually. You want a column of integers to display neatly stacked with consistent width, using space padding instead of zeros for a cleaner look in plain text.
Examples
Pad with zeros
Input
42
Output
00042
Longer integers stay intact
Input
5 123456
Output
5 123456
About the Left-pad Integers tool
Left-pad Integers runs as plain JavaScript in your browser tab, with no server behind it. Pad integers on the left up to a fixed width. Whatever you put in stays on your device from start to finish.
The tool is part of EditSafely's Integer Tools section, 133 single-purpose utilities built around the same idea: open the page, get the result, keep your data to yourself.
You can shape the output with 2 settings, including Target width and Fill string, and the result refreshes the moment you change one. 2 worked examples further down the page show exactly what the tool produces for real inputs.
That local-first design has practical benefits beyond privacy. The tool keeps working on a flaky connection once the page has loaded, results are instant because nothing round-trips to a server, and it is safe to use with confidential material.
Frequently asked questions
Does Left-pad Integers cost anything?
Yes, it is completely free. All 2,658 tools on EditSafely work without an account, a subscription or usage limits.
Is it safe to paste sensitive or confidential data?
No data leaves your device. The whole tool is JavaScript that runs inside your browser tab, so there is no upload, no server-side processing and no log of what you did. If you disconnect from the internet after the page loads, it keeps working.
How much text can I process at once?
There is no fixed limit. Because the work happens on your own device rather than on a shared server, the practical ceiling is your machine's memory, which comfortably handles inputs far larger than typical online tools allow.
Do I need to sign up or install anything?
Nothing to install and no account needed. Open the page in any up-to-date browser, including on a phone or tablet, and the tool is ready.
How do I use the result?
The output panel has a one-click copy button, and you can keep refining the input while you work; the result updates in place as you type.