Frequently Asked Questions

Is xCubes Solver really free?

Yes. There are no sign-ups, no payments, and no usage limits. The site is supported by small advertising banners. You can solve as many cubes as you like, of any size from 2×2 to 15×15, without paying or registering anything.

Does this use AI?

No. The solver uses classical, deterministic search algorithms — the two-phase Kociemba algorithm for 3×3 and IDA* search with precomputed lookup tables for larger cubes. No machine learning, no neural networks, no AI of any kind is involved. Given the same scramble, the solver will always produce a valid solution. See the about page for more on the algorithms used.

What sizes can I solve?

Every NxN size from 2×2 to 15×15. Pick your size from the menu at the top. Different sizes use different solving algorithms internally, but the user experience is the same: enter the colors, press solve, get a step-by-step solution.

How long does a solve take?

For a 2×2 or 3×3, you get the solution instantly (milliseconds). For a 4×4 to 6×6, expect 2–10 seconds. The 7×7 typically takes 30–60 seconds. Larger cubes (10×10 and above) can take 1–5 minutes on a busy server day. The first time a given cube size is solved after a server restart, it may take longer because the algorithm loads its lookup tables into memory.

The solver says "Couldn't solve this position." What happened?

This almost always means there's a mistake in the colors you entered. The most common errors:

Double-check your entry carefully. A photo of your physical cube next to the website helps a lot.

Can I use the solver on my phone?

Yes, the site works on phones and tablets. The color-entry grid is easier to use on larger cubes (7×7 and above) with a wider screen, but it's fully functional on mobile. There's no app to install — just visit xcubes.app in your phone's browser.

Why are some solutions so long?

The solver prioritizes finding a valid solution quickly over finding the absolute shortest possible one. For a 3×3 the solution is usually within a few moves of the theoretical optimum (20 moves). For bigger cubes, the solver uses reduction methods that produce around 150 moves for a 7×7 and over 800 for a 15×15 — comparable to what experienced human cubers do, but not shorter.

Finding the truly shortest solution for a 7×7 is an open research problem and would require hours of computation per scramble. That's not practical for a free online tool.

What if my cube has stickers worn off or missing?

You'll need to be able to identify every sticker's color to use the solver. If a sticker is missing, look at the piece's other stickers and use the cube's standard color scheme to deduce what color it should be. Once you know all 6 × N² stickers, enter them as usual.

Can I solve a 17×17 or 21×21?

Not on xCubes Solver — we cap at 15×15. Algorithmically, the reduction method scales to any size, but storage and computation grow quickly. Most cubers who own 17×17 or 21×21 cubes solve them by hand and don't need a solver anyway.

Why is there a "classic" version and a new design?

The site has two interface designs: the v2 (futuristic) is the modern default, and the classic (v1) is the original look, kept for users who prefer a simpler aesthetic. Both run the same solver and produce the same solutions. You can switch at any time using the buttons in the header or the card at the bottom of the page.

Do you store the cubes I solve?

The site logs anonymous statistics (cube size, solve time, success or failure) for performance monitoring, but it does not store the actual scramble or your IP address against a personal identity. See the Privacy Policy for details.

How can I help / report a bug?

Use the "Contact / business inquiries" link in the site footer to reach the maintainer. Bug reports are very welcome — please include the cube size, the scramble (if you can), and what went wrong.

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