Petrus Method for Big Cubes — Step-by-Step Guide from 4×4 to 20×20

[6 by 6]

“This thread will contain my Petrus method guide for big cubes. I’ll post the PDF and updates here.”

 

[6 by 6]

Hey everyone


I’m excited to share a detailed Petrus-style method I’ve developed for solving big cubes — from 4×4 all the way up to 20×20.


The idea is to start on a 4×4 to grasp the method, then scale up while keeping the same logical structure.


I’ve prepared a step-by-step guide in a PDF, covering block building, efficient edge pairing, and smooth layer transitions for each size.


Here’s the PDF on Internet Archive: https://archive.org/details/petrus-method

https://www.reddit.com/r/Rubiks_Cubes/comments/1mksgja/petrus_method_for_big_cubes_stepbystep_guide_from

If anyone tries it or gets stuck, feel free to ask questions here — I’m happy to help or discuss optimizations!


Happy cubing!
Shridarshan Mishra
6 by 6

 

[6 by 6]

Please share your feedback, tips, or creative ideas! I’m always looking to try new things and improve the method, and I’d love to hear your thoughts.

 

[Athefre]

I like some of the ideas here.

One standout trait of Petrus is reduction after 2x2x3. There's EO in the current Petrus form, and in the past Lars was also permuting the corners to be <U, R> solvable. After these reductions the rest is solved. For big cubes of all sizes I feel like the Petrus way would be to pair edges once reaching the stage where just two layers are unsolved. We've seen a couple of recent 4x4 methods do edge pairing after a 3x3x4 block. So your starting ideas and earlier edge pairing could be combined.

 

[6 by 6]

I like some of the ideas here.

One standout trait of Petrus is reduction after 2x2x3. There's EO in the current Petrus form, and in the past Lars was also permuting the corners to be <U, R> solvable. After these reductions the rest is solved. For big cubes of all sizes I feel like the Petrus way would be to pair edges once reaching the stage where just two layers are unsolved. We've seen a couple of recent 4x4 methods do edge pairing after a 3x3x4 block. So your starting ideas and earlier edge pairing could be combined.

Thanks a lot for the detailed insight! That’s a really interesting point about delaying edge pairing until only two layers remain.

I like the idea of experimenting with a 3×3×4 or similar block before pairing edges - that could make the transition feel smoother on big cubes. I’ll definitely try combining that approach with my current structure and see how it affects flow and lookahead.

Appreciate the feedback — this gives me a fresh angle to explore!

 

[6 by 6]

Quick Update

I’m planning to upload a walkthrough video soon showing how the Petrus Method can be applied on a 6×6.
In my PDF guide, I have applied Petrus method in 9×9, but since my 9×9 cube recently broke (and I don’t currently have a 7×7 or 8×8), I decided to try the concept on my 6×6 instead.

Don’t mind the video quality when it’s out - my main goal will be to clearly explain the logic and thought process behind using Petrus on bigger cubes.
I think it’ll be interesting for anyone curious about how the Petrus principles can extend beyond the 3×3.

Thank you, and happy cubing everyone!

 

[6 by 6]

6×6 Petrus Method – My Approach (Walkthrough Video)​

I just recorded a small walkthrough showing how I apply the Petrus Method on a 6×6.
This is my personal approach, and I tried to explain the logic as clearly as possible.
If you want, I can upload more walkthrough solves in the future for better clarity and deeper understanding of how Petrus concepts scale to big cubes.

Also, one question ---
Would it be useful if I also make a video on my classic reduction approach on 6×6, where I explain my full thought process while solving?
If you guys are interested, I’ll definitely record that too.

Video Link - https://drive.google.com/file/d/1U1Ksk9Xzrzmjeuo-w-nmK4l__aFKP2iZ/view?usp=sharing

Thank you, and happy cubing everyone!

 

[Adm_cb]

Do it for 21×21

 

[6 by 6]

Do it for 21×21

Absolutely not

 

[6 by 6]

Quick update!

I’ve decided to move all my big cubes walkthrough solves to YouTube because my Drive space is filling up fast.

From now on, I’ll upload every 7by7 and 6 by 6 solve to YouTube and share the link here in this thread.
This makes the videos easier to watch, cleaner to post, and accessible for everyone globally.
If you want to follow all my big cube content here is my channel: https://www.youtube.com/@Big_Cubes_Specialist

video link:

 

[6 by 6]

8×8 Solve Using Petrus-Style Method

I tried an 8×8 solve using my Petrus-style approach. I had a small mix-up near the end but still managed to finish the solve.

I’ve added more details in the YouTube description.

Video Link:

More big cube Petrus experiments coming soon!
Thank you and happy cubing!

 

[Adm_cb]

Do it for a 34×34

 

[6 by 6]

Do it for a 34×34

Give me a week to evolve into an octopus, then I will try it

 

[Caleb Valenzuela]

Do it for 21×21

what’s your obsession with 21x21s

 

[6 by 6]

what’s your obsession with 21x21s

I am not solving a 21×21
It’ll take so long that YouTube will drop the video quality out of pity.
I might have to upload it in parts… and even my mobile cube app only goes up to 20×20

 

[6 by 6]

Did a quick Petrus-style solve on 3×3 today

Since I’ve been using Petrus on every big cube recently, I thought…
why leave the 3×3 out of the fun?

So here’s a light 3×3 solve using the same Petrus-style flow -the smallest cube joining the big-cube party for once!

Video Link:

I’ve also made a playlist for all my Petrus-method solves, so everything stays organized in one place.

Playlist Link:

Petrus Method for Big Cubes – Full Solve Series

A complete collection of all my big cube solves using the Petrus method. If you want every solve in one clean, organized series - this is the place.

youtube.com

More solves coming soon!

Thank you and happy cubing!

 

[6 by 6]

9×9 Solve Using Petrus-Style Method
Tried another big cube today, this time the 9×9!
I decided to put Petrus method through another stress test and somehow managed to finish the solve in one clean attempt.
Not sure if it was skill or pure luck - probably a bit of both , also i think i practiced 9 by 9 a lot with Petrus method in physical cube, before publishing a pdf guide, that's why i think i solved cube in one go.

Solving big cubes on mobile is always an adventure…
especially because on 11×11 or 13×13 etc, it happens with me that after reaching the last steps and then one wrong algorithm move destroys the entire cube.

Solving a 9×9 on mobile still feels like playing a boss fight on hard mode… but I survived it.


Video Link:

And honestly, I don’t even want to think about what will happen when I try a 17×17 or 20×20.
At that point, either I’ll become a certified big-cube superhero… or the cube will eat me alive and I’ll vanish mid-solve.
We’ll find out in the future - if I survive

More big cube attempts coming soon!

Thank you and Happy cubing!

 

[abunickabhi]

Hey everyone


I’m excited to share a detailed Petrus-style method I’ve developed for solving big cubes — from 4×4 all the way up to 20×20.


The idea is to start on a 4×4 to grasp the method, then scale up while keeping the same logical structure.


I’ve prepared a step-by-step guide in a PDF, covering block building, efficient edge pairing, and smooth layer transitions for each size.


Here’s the PDF on Internet Archive: https://archive.org/details/petrus-method

https://www.reddit.com/r/Rubiks_Cubes/comments/1mksgja/petrus_method_for_big_cubes_stepbystep_guide_from

If anyone tries it or gets stuck, feel free to ask questions here — I’m happy to help or discuss optimizations!


Happy cubing!
Shridarshan Mishra
6 by 6

Petrus solve on a 20x20 is super wild.

I bet anyone would be interested in doing that , or if it is even worth the effort

 

[6 by 6]

Petrus solve on a 20x20 is super wild.

I bet anyone would be interested in doing that , or if it is even worth the effort

But I never jump straight to the final boss - I level up cube by cube.
That way, when I reach 20×20, it won’t feel like a challenge… it’ll feel like the next logical step.
Worth the effort? Probably not. But I also want to challenge myself to see how much patience I have… and how much frustration can i handle.

 

[6 by 6]

10×10 walkthrough solve (Petrus method)

Bigger cubes start getting chaotic, but surprisingly this one went fairly clean and I managed to finish it in a single attempt.

Also, from now on I’ll be sharing my failed solves too whenever I mess up - not just the clean ones.
Should be fun and painful to look back at

Video:

Now that 10×10 is done, I’m curious how far it goes!
More big cube solves coming soon!

Thank you and Happy cubing!