Change List Length Online
Change List Length Truncate, pad, or cycle any list to a target length. Free, offline, client-side - with auto-detected separators and custom placeholder text.
Resize any list to an exact length with one of three modes: truncate to the first N items, pad with placeholder text, or cycle the original items until the target is reached. Auto-detects the input separator and lets you choose a different output separator.
How to Use Change List Length Online
- Paste your list. Any separator works. Leave the Input separator on "Auto-detect" and the tool picks whichever of newline/comma/semicolon/tab/pipe shows up most on the first 4 KB of your paste.
- Pick the output separator. Defaults to newline. Useful when you need to convert between formats while also resizing - e.g. paste a CSV row, get a newline list of 10 items back.
- Set the target length. Any positive integer up to 100,000. Beyond that the tool refuses to avoid freezing the browser.
- Pick a mode. Truncate keeps the first N items (no effect when target ≥ current). Pad appends placeholder items like
Item 4, Item 5when target > current, with the prefix you choose. Cycle repeats the original sequence until the target is reached - great for filling templates. - Toggle "Skip empty items" if needed. On by default, so blank lines from a sloppy paste do not count toward the length.
- Click Adjust or press Ctrl/Cmd+Enter. The input is also debounced at 200ms so typing produces a live preview without pressing the button.
- Copy or download. Copy places the output on your clipboard. Download saves a .txt file with the new length and a timestamp in the filename.
Frequently Asked Questions
Is my data secure?
Yes. All processing runs in your browser with plain JavaScript – the list is never uploaded or logged. No network request touches your paste.
Is this tool free?
Yes – completely free with no registration, no usage limits, and no hidden fees. Use it for personal or commercial work.
What’s the difference between pad and cycle modes?
Pad fills with placeholder items (Item 4, Item 5 … using the prefix you chose). Cycle repeats your original items in the same order (apple, banana, cherry, apple, banana …). Pad keeps the new entries visibly fake; cycle keeps them plausible.
What happens in truncate mode?
Truncate cuts the list to exactly target items by keeping the first N. If target is greater than or equal to the current length, the list passes through unchanged – truncate never adds items.
Can I use different separators for input and output?
Yes. Pick any input separator (or let Auto-detect choose for you) and a different output separator – tab in, comma out, pipe in, newline out, whatever you need.
What does “Skip empty items” do?
Trims whitespace from each item and drops empty entries before adjusting the length. Useful when pasting from clipboards that add stray blank lines, or when using space as a separator with double spaces.
How large of a list can I process?
Up to 100,000 items runs in well under 100ms on a modern laptop. Beyond that the tool refuses with a clear error rather than silently freezing the page.
Can I customize the placeholder text in pad mode?
Yes. The “Placeholder prefix” field turns into the first word of every added item – so Row gives you Row 4, Row 5, … Leave it empty to add blank items instead.
What are common use cases for changing list length?
Preparing test data with an exact row count, generating synthetic datasets, creating placeholder bullet lists in docs, truncating long lists to a preview, or cycling a small list to match the row count of another dataset.
Will the original order of my items be preserved?
Yes in every mode. Truncate keeps the first N in original order, pad appends after the originals, and cycle repeats the sequence starting from item 1 each time.