Drop your .ccurve or .cc4 file
or click to browse
Your file is sent to our server, converted in memory and sent straight back. It is never written to disk and it is never stored. One file at a time, up to 100 KB, and a real curve file is a couple of kilobytes.
Custom Curve Converter: .ccurve to .cc4 and back
Drop in a Custom Curve mouse acceleration profile and get the other version back. Custom Curve 3 saves .ccurve files, Custom Curve 4 saves .cc4, and this tool goes both ways. It is free, there is nothing to install, and you do not need an account.
Already have a curve? Make it better.
Tell the whaamkabaam coach how your aim feels, in plain words. It retunes the curve and keeps every version, so you can always go back.
Where to find more Custom Curve files
Players post their curves in the whaamkabaam Discord and we collect them in one place. Most posts come with a curve file you can download, free and with no account, and the rest are screenshots with nothing attached. Type in your DPI and your in-game sens and the closest ones come first.
Browse curves other players postedWhich direction do you need?
Custom Curve 3 to Custom Curve 4 (.ccurve to .cc4)
Custom Curve 4 can already open a .ccurve file on its own. Press Ctrl+I inside Custom Curve 4, pick the file, and it loads. If that is all you need, you do not need this page.
Use the converter when you want a real .cc4 file in hand: to keep as a backup, to send to someone, or to load on a machine where Custom Curve 4 is not installed yet.
Custom Curve 4 back to Custom Curve 3 (.cc4 to .ccurve)
This is the direction with no alternative. Custom Curve 4 only ever exports .cc4, and Custom Curve 3 is discontinued and can no longer be downloaded, so nothing is coming that would teach it the new format. If you or the person you are sending a curve to is still running Custom Curve 3, this converter is the way across.
About a third of the files converted here go in this direction.
What survives the conversion, and what does not
The shape of your curve comes through in both directions. Everything else depends on which way you are going, because the two versions do not store the same things. This is the whole list.
| Going to Custom Curve 4 | Going back to Custom Curve 3 | |
|---|---|---|
| The curve shape | Resampled and refitted to match the shape | Resampled and refitted to match the shape |
| A separate vertical curve | Kept | Kept |
| Number of points | Changed. Custom Curve 4 draws curves differently, so the converter picks new points, up to 32, that sit on the same line | Changed, for the same reason |
| Flat start and tail slope | Rebuilt using Custom Curve 4's own slope settings | Dropped. Custom Curve 3 has nowhere to put them |
| Per-point weights | Every point is set to 0.5 | Dropped |
| Hand accel modulation | Off | Dropped |
| Bias curve, rotation, Soft Angle Snapping | Set to defaults | Dropped |
| Input and output smoothing | Off | Dropped |
| DPI, polling rate, normalization | DPI 800, polling rate Auto, normalization off | Dropped |
| Profile name and description | Taken from your filename | Dropped |
| Custom Curve 3's own settings block (lines 6 to 12) | Never read. Custom Curve 4 defaults are written instead | Written as our defaults, not yours |
How the shape survives. Custom Curve 3 draws its line through the points you place. Custom Curve 4 draws a line that its points pull towards, so copying the numbers across changes the curve. That is what this converter used to do until August 2026. It now samples the curve and refits it, so the new file traces the same line rather than the same numbers. We have not yet loaded a converted file into Custom Curve 4 and compared the two on screen.
One more thing if you go up and come back. A round trip does not return your original file. Lines 6 to 12 of a .ccurve hold Custom Curve 3's own smoothing and DPI settings, the converter never reads them on the way up, and on the way back it writes its own defaults there instead. Keep your original file.
After the file downloads
Open Custom Curve 4 and press Ctrl+I, then pick the converted .cc4 file.
Then open the Output tab and set your real DPI. The converter writes 800 and leaves normalization off, because a .ccurve file does not carry a DPI the converter can trust. Custom Curve's own guidance is to run 1600 DPI or higher.
Coming back the other way, load the .ccurve in Custom Curve 3 like any other profile, and keep your original .cc4.
If your file will not convert
The converter refuses a file rather than guess at it. Here is what each message means.
| The message | What it means |
|---|---|
File must be .ccurve or .cc4 | The converter reads the file extension, not the contents. If you renamed the file, rename it back. |
File too large (max 100KB) | A real curve file is a couple of kilobytes. Anything near 100 KB is not a curve file. |
File is empty | The file has no content in it. Export a fresh copy and try that one. |
File must be valid UTF-8 text | The file has to be plain text the server can read. A file saved in another encoding lands here. |
Invalid ccurve file: Invalid .ccurve format | A .ccurve has to be exactly 13 lines, and every line has to be numbers separated by spaces. Files that have been opened and re-saved by a text editor, truncated, or hand-edited usually land here. Export a fresh copy out of Custom Curve 3. |
Invalid cc4 file: Missing or invalid XCurve | A .cc4 has to be readable JSON with an XCurve block in it. If the file was edited by hand, start again from a fresh export. |
Invalid cc4 file: XCurve.Points must be a list with at least 2 points | The file was read, and the curve in it has fewer than two points. Two points are the least a line can be drawn through. Open the curve in Custom Curve 4, place a second point, and export again. |
What a .ccurve file is, and what a .cc4 file is
What is a .ccurve file?
A .ccurve file is a mouse acceleration profile saved by Custom Curve 3, a Windows program that changes how far your cursor moves for a given speed of mouse movement. It is plain text, exactly 13 lines of numbers. The first lines hold the points of your horizontal curve, the next hold the vertical one, and the rest hold Custom Curve 3's smoothing and DPI settings.
What is a .cc4 file?
A .cc4 file is the same thing saved by Custom Curve 4, the current version of that program. It is JSON rather than plain text. Each point on the curve is stored as a speed, a sensitivity and a weight, and the file also carries the settings Custom Curve 3 never had, including hand accel modulation, the bias curve and Soft Angle Snapping.
Custom Curve 3 and Custom Curve 4, the short version
Custom Curve is made by G.I.S. and sold at mouseacceleration.com. Custom Curve 4 costs $19.99 once, runs on Windows 10 and 11, and comes with a 14-day free trial. There is no free edition and the maker says none is planned. If you bought Custom Curve 3 Pro, your key works in 4 and the upgrade costs nothing. Custom Curve 3 itself is discontinued and can no longer be downloaded, so if you still run it, keep your installer.
What Custom Curve 4 adds: control over how hard each point pulls on the curve, its own behavior past both ends of the curve, hand accel modulation so the curve reacts to how fast your hand is speeding up and not only how fast it is moving, a bias curve that splits horizontal and vertical sensitivity by the angle you are moving, Soft Angle Snapping with a built-in detector, input and output smoothing, and a polling rate override. Separate horizontal and vertical curves are not new: Custom Curve 3 had those too.
Prices and versions checked against mouseacceleration.com on 12 September 2026. Custom Curve 4 build 4.4.256.
Frequently asked questions
Related
- How the coach tunes a curve, if you want the curve itself to change and not just the file format
- Curves other players posted, free Custom Curve files from the whaamkabaam Discord, most of them ready to download
- What the studio costs
- What players say about their curves
- Custom Curve itself, from the people who make it
Last checked against Custom Curve 4 build 4.4.256 on 12 September 2026.