ALWAYS Do This To Your CARPENTRY + WOODWORKING Projects! (How to SQUARE UP Cabinets/Floors/Walls…)

ALWAYS Do This To Your CARPENTRY + WOODWORKING Projects! (How to SQUARE UP Cabinets/Floors/Walls…)

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Flush Vs. Proud:

ALWAYS Do This To Your CARPENTRY + WOODWORKING Projects! (How to SQUARE UP Cabinets/Floors/Walls…)

Understanding “squareness” is one of the most important parts of becoming a good carpenter or woodworker. This short video from The Honest Carpenter will explain what “square” means in carpentry and construction, how we determine if something is square, and how we keep it square!

As I mentioned in my “Plumb, Level, Square” video, the word “square” in construction simply means two lines, components or objects are sitting at a perfect 90-degrees to one another.

Building things square is massively important in carpentry, because elements built out of square will impact later phases of work that are built upon the first.

To determine square for very small objects like little boxes, you can just slide a TRY SQUARE into an interior corner and make sure both legs of the tool are touching the material evenly.

For anything slightly larger like a cabinet, it’s better to “pull diagonals” or “pull corners” to see if something is square.

Hook your tape measure onto one corner and pull to the opposite outside corner–note the measurement. Now pull from the other corner on the same side to the other opposite corner, and note that measurement. If the numbers are different, then your box is OUT OF SQUARE!

One corner is probably squeezed in, meaning that the other corner on that end is being pushed out. Rack the box back into shape and pull corners again until the numbers match up.

On very large structures like floors and walls, it’s best to use the 3-4-5 METHOD. Pull three feet on one leg of the structure and make a mark at 3′. Then pull 4′ out the other leg and make a mark. Now measure the distance between the two marks. If it’s 5′, then your structure is square. If it’s not 5′, then your structure is out of square–shift it into the right shape.

Once you have an object squared up, brace it by shooting a scrap piece of wood across two adjacent legs, locking the shape into place until glue dries, or your finished building!

Thanks for watching!
The Honest Carpenter


  1. George Gonzalez-Rivas on April 22, 2022 at 6:18 pm

    This was a very useful video… I have been that guy who "just sanded it flush…"
    But I was disappointed by your "ask somebody smarter" remark re 3-4-5 triangles. You obviously understand the principle and apply it daily. YOU are an excellent person to explain it. Too often we see people dismissing math/science as a remnant from the High School philosophy that cool people aren’t smart. You’re better than that.
    Just explain, like the Scarecrow in OZ, that the square of the hypotenuse is equal to the sum of the square of the sides. H^2= S^2 + S^2. Hence 3-4-5 works since 9+16=25 Using 3-4-5 , as opposed to the infinite number of alternatives, is simply because those are the smallest integers that solve the equation.

  2. WHK 2eZ on April 22, 2022 at 6:19 pm

    I love this channel and always learn something new!

  3. Dan P on April 22, 2022 at 6:19 pm

    The fancy name of those 3-4-5 patterns is Pythagorean Triplets; other relevant ones would be 5-12-13 and 7-24-25, in addition to the multiples of each as mentioned. They are solutions to the Pythagorean Theorem where all of the legs of the triangle are rational numbers.

  4. Davil on April 22, 2022 at 6:22 pm

    You are an amazing speaker! Thank you for All your videos! I learn in everyone of them!

  5. chris malcomson on April 22, 2022 at 6:22 pm

    When I make a chest with lots of drawers the same size I make a perfectly square interior former which makes all of them exactly the same. Formers are a great way to make multiples perfectly square without having to measure continuously.. Didn’t know that triangle thing, worth remembering. Why was it I was crap at math at school when my whole life as a cabinet maker is all about numbers?

  6. David Sigetich on April 22, 2022 at 6:23 pm

    Great tips for even small projects. Then there’s trying to figure out the source of un-squareness. I just discovered that my table saw was lying to me by about 1/2 of a degree or so, so the four sides of a box could be 2 or 3 degrees out. Fixed it! Thank you!

  7. The Auto Driver on April 22, 2022 at 6:24 pm

    You have brought up the question I have been asking lately about squaring things and which sawing system I should buy since I need either a table saw or a track saw. I watched a Kreg video using their track saw and ACS system and how their system made squaring easy and virtually certain. But it is expensive. Is there a less expensive way – and just as good of a way – to come up with the same consistent results of the ACS system?

  8. Me me on April 22, 2022 at 6:25 pm

    I am a rookie and I am dealing with this right now. It sucks. Lol

  9. Derek Dean on April 22, 2022 at 6:27 pm

    Everything I make is 91 degrees. 91 degrees. 90 degrees. 88 degrees.

    I give the item to someone. And I wait…

    We’re all evil geniuses in our own way.

  10. gizmorow21 on April 22, 2022 at 6:28 pm

    The Best Teachers are not the ones that know the most, but the ones that cause the most to know. Great job.

  11. Troy Stein on April 22, 2022 at 6:29 pm

    I have been looking for a straightforward video like this for forever! Thank you!!!

  12. Mr. Rusty on April 22, 2022 at 6:29 pm

    Also, there’s the 5-12-13 which is the same concept as 3-4-5 but the angle is more acute…

  13. David Magaña on April 22, 2022 at 6:30 pm

    Muy instructivo!

  14. 7F0X7 on April 22, 2022 at 6:32 pm

    How fitting is it that Jesus was a carpenter by trade and also the perfect corner stone which sets the foundation and is the rubric by which all adjacent foundational material is fitted and measured out. If your original corner to corner measurement is not perfect, then all built upon it will exacerbate the flaw. There’s a spiritual lesson here as well.

  15. Mr. Autumn on April 22, 2022 at 6:32 pm

    Thank you for this video. Sometimes the little things are the biggest pain in the ass.

  16. John White on April 22, 2022 at 6:34 pm


  17. Chef Spenser on April 22, 2022 at 6:34 pm

    Well done, once again-thanks!

  18. Dan Alaniz on April 22, 2022 at 6:35 pm

    Thanks! I just started DIY woodworking last year and I have learned so much from your videos. I’ve made the mistakes you described and now I need to incorporate this lesson, some discipline and patience into my work.

  19. Robert Hiday on April 22, 2022 at 6:36 pm

    nice.very well done. thanks.

  20. Keith Vance on April 22, 2022 at 6:36 pm

    Got the wood cut for a homemade arcade machine this is great advice. I am a very amateur wood worker whose expertise is electronics, I want it to look as good in real life as in my head.

  21. seefujoe169 on April 22, 2022 at 6:37 pm

    Excellent! Great example. Thank you.

  22. Veronica White on April 22, 2022 at 6:37 pm

    Thankyou, Ethan. That was very informative and much appreciated!

  23. Barrel Cooper on April 22, 2022 at 6:43 pm

    Tenacious D-iyer! I love it

  24. Dave Santiago on April 22, 2022 at 6:44 pm

    holy crapballs, i didnt know this is where im gonna be applying my grade 10 math (pythagorean theorem) in real life! hahahahah amazing info. its so frustrating sometimes that even though im trying really hard, i cant seem to square it.

  25. Christopher Cook on April 22, 2022 at 6:46 pm

    Great refresher tips 👍🏻

  26. Sundra Poonan on April 22, 2022 at 6:47 pm

    Spot on Ethan, this is brilliant advice on how to do things right (excuse the pun) from the start, and continue to check as you build, to ensure that everything stays square. Thank you for sharing your knowledge and experience, I really appreciate it.

  27. Jake Lilevjen on April 22, 2022 at 6:47 pm

    I suffer from chronic perfectionism, and get pissed when my 5’ x 7’ table top is out of square by 1/16” when measured from corner to corner. Does anyone have any experience or guidance on how close is good enough? When does out-of-square really start impacting the quality of your work? Is a 0.1 degree error (89.9 or 90.1 degrees instead of the desired 90) good enough for most applications? How about fine furniture?

  28. George Spindler on April 22, 2022 at 6:48 pm

    Hang a few doors. String line corner to corner. Measure diagonally each way. Flatness and square. I string line my stair nosing. Corner to corner measurements are the best way on large projects. The larger the job the more innovative you have to be. Square, flat, plumb.

  29. The Frank Perspective on April 22, 2022 at 6:48 pm

    I have absolutely never done every single mistake mentioned in this video. Nope. Not at all…

  30. Christopher Ortiz on April 22, 2022 at 6:48 pm

    Great info.. I have learn a lot from your videos. Appreciate you take the time explaining this methods. 😄

  31. Bari Khan on April 22, 2022 at 6:49 pm

    Another great video!

  32. Gary Williams on April 22, 2022 at 6:50 pm

    Thank you for his video tutorial – your commentary and explanations were clear, simple and compelling. Having just assembled my first ever – test piece – toy chest (slightly out of square) I will employ your ‘squaring’ methodologies next time 👍

  33. Dave on April 22, 2022 at 6:50 pm

    I like the 3,4,5 😉

  34. Vociferon Herald of the Winter Mist on April 22, 2022 at 6:55 pm

    One of my favorite kinds of videos to watch are finish carpenters fixing all of the mistakes of the builders and/or time. Just a slight settling of the foundation can make a HUGE difference when it comes to placing trim. I’ve seen some old houses with HORRIBLE issues. Try to put in cabinetry that goes almost up to the ceiling when the ceiling is way off kilter. It’s an art to make it work.

    This has always been a lingering question in my mind. When the structure is out of square and out of level do you match the lines of the house to continue the illusion that it’s consistent or do you go with plumb, level, and square despite the fact that it’ll be glaringly obvious.

  35. Devon Callahan on April 22, 2022 at 6:56 pm

    Should be "Right" not "Square" . Then you could say, "That aint right."

  36. Ty Cox on April 22, 2022 at 6:56 pm

    Square is only part of the challenge. Since we live in a 3 dimensional world, plum and level matter equally.

  37. Jason Hanson on April 22, 2022 at 6:57 pm

    Gotta love that 3-4-5 method.

  38. Mr. Ken on April 22, 2022 at 6:58 pm

    Now I know the importance of not being a square peg in a round hole.

  39. Wolfman on April 22, 2022 at 6:59 pm

    Thank you!!!!! Great Info!!! 😀

  40. Patricio Orozco-Contreras on April 22, 2022 at 6:59 pm

    Great vídeo !!! Thanks a lot for sharing 🙌🙌🙌

  41. Michael Bradford on April 22, 2022 at 7:02 pm

    Square and Plumb…a framers motto.

  42. Kelly B on April 22, 2022 at 7:04 pm

    Thank you for this video. Especially the 3-4-5 method to check your corners on larger objects. I just built a 4×8 table out of 2x4s and was pulling my hair out because every time I checked the diagonal it wasn’t equal. Very frustrating. Eventually got it but using that method would have saved a lot of time.

  43. CF542 on April 22, 2022 at 7:05 pm

    I’ve learned more from YouTube on DIY than I could have on my own. Content like yours literally has saved me hundreds if not thousands of dollars.

  44. Adrian on April 22, 2022 at 7:08 pm

    8:30 not oblique, OBTUSE (because an acute angle is also oblique) also, those are Pythagorean triples / numbers

  45. Scott Bitz on April 22, 2022 at 7:09 pm

    I understand that this was somewhat exaggerated to make a point, but the beauty of the panel addition to the back is that if your outer measurements match, you should know that it’s out of square as soon as you put it on!

    Of course, it’s also why I’ll be using square clamps when I’m making my wife’s hanging yarn shelf because I want it to be perfectly square and just be easier to build by myself that way!

  46. Mr. Rusty on April 22, 2022 at 7:11 pm

    I discovered 3-4-5 when I was maybe 7 years old building legos… I had no idea what it was or how important it is to building. But legos are square anyways when you put them together if they are 2 pegs wide or more. I’m almost 40 and use legos to make squares, plaster forms, or use as supports on corners when glueing together HO scale buildings and just scratchbuilding in general.

  47. Norman on April 22, 2022 at 7:11 pm

    You are doing a great job on your channel! You are missing out on potential viewers by not using a service such as P r o m o s m!!

  48. rich caro on April 22, 2022 at 7:12 pm

    Nice explanation. Thank you

  49. C P on April 22, 2022 at 7:17 pm

    Thank you for this awesome video! You’re a natural teacher!

  50. Lesley Ghost Dragon on April 22, 2022 at 7:18 pm

    Whenever I (arrogantly) think I know enough about a subject, that there’s really nothing more to learn, and so maybe I don’t need to watch that video of yours…, you always include something fantastic that I hope to remember to use in my next project! 🤓
    Thanks so much for your great videos 💟