Calculation
Formula and game rule
Shell = width×height×depth − max(width−2,0)×max(height−2,0)×max(depth−2,0).
Building
Hollow Box Calculator
Calculate the exact number of blocks in walls, floor and roof together.
Hollow Box CalculatorTry it now
Your Minecraft mission
- Shell blocks
- 368
- Inside space
- 280
- Full stacks
- 5
Game rule: Results update instantly while you type.
Step-by-step guide
How to use the Hollow Box Calculator
Enter the outside width, height and depth of the rectangular structure.
Use shell blocks for one-block-thick walls, floor and roof together.
Review interior volume and convert the shell total into stacks.
Worked example
Example result
A 12×6×9 box has 648 total positions and 280 interior positions, so its complete shell needs 368 blocks.
What to check before using the result
- The shell includes both floor and roof; subtract those areas if you only want vertical walls.
- Very small dimensions may have no interior because opposite walls touch.
Java and Bedrock Edition
This is edition-independent geometry. The stack result assumes a 64-stack building material.
This page is designed for players looking for a Minecraft hollow box calculator, wall block calculator, house material calculator. The calculator runs locally in your browser and updates without sending your world coordinates or command inputs to the server.
Common questions
Hollow Box Calculator FAQ
Are corners counted more than once?
No. Subtracting the interior from the full volume counts every shell position exactly once.
Is the shell always one block thick?
Yes. For thicker walls, calculate the outer volume and subtract an interior reduced by twice the desired thickness.