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Stanford Mattress Extender

This post describes how my friend Briar and I made a width extender for a twin -> full sized bed. This one is for sure compatible with the dorm bedframes at Stanford University, but might come in handy in your dorm too! The design is far from original.

All dimensions are in US Imperial Units, because you are probably going to a US hardware store.


The bedframe

A Twin XL bedframe is 36" x 80", theoretically. Your bedframe should be this size.

A full-sized mattress is 54" x 75". We need to increase the width to match this.


  • Electric Jigsaw
  • Electric Drill


  • 3-1/2" x 3/4" Lumber (8x 8' long OR 4x 12' long)

    Wood material is up to you, but make sure it doesnt flex too much.

    If you have a way to transport longer lengths of lumber, then you can be more efficient.

    Note to future self - I don’t think 3-1/2” x 3/4” is the advertised size. Its probably 4”x1” or something. These are just the measurements I took after losing the receipt.

  • 32x #6 x 1-1/4" Flat Head Wood Screws.

    Pack of 50 or 100 probably.


Two simple steps.

1. Cut the wood pieces

Use the jigsaw and make all these cuts.

Then, for all 52" pieces, use the jigsaw to round the corners. Be careful and keep control of the blade. Also, dont leave extra material. These are the width pieces, which should be slightly less than the width of your full-sized mattress (54").

2. Assemble

Lay the pieces on the floor and screw them together. Use two screws diagonally offset at each joint.

This is the only important dimension.


Just put em on the bedframe 👍