Blockspan

Blockspan is a client-side Fabric/Forge mod for builders who want quick, vanilla-feeling measurements while planning survival builds. Select two block positions and Blockspan shows a subtle in-world box with labels, dimensions, volume, distance, center point, and coordinates.

It is safe for survival worlds because it does not add blocks, items, entities, recipes, world generation, or server-required features. Saved areas are stored only in your local client config.

How to use

Look at a block and press R to set Point A. Look at another block and press R again to set Point B. The selected area will appear in the world with its length, width, height, and volume.

Press V to open the Blockspan menu, where you can rename the current area, choose a color, save it, hide/show saved areas, or delete saved areas.

Controls

R - Set the next point
Sneak + R - Force set Point A
Sprint + R - Force set Point B
C - Clear the active points
B - Toggle the Blockspan overlay
V - Open the Blockspan menu

Commands

All commands are client-side:

/blockspan label <name> - Set the current area label
/blockspan color <color> - Set the current area color
/blockspan colors - List available colors
/blockspan save [name] - Save the current selected area
/blockspan list - List saved areas in the current dimension
/blockspan enable <name or id> - Show a saved area
/blockspan disable <name or id> - Hide a saved area
/blockspan toggle <name or id> - Toggle a saved area on or off
/blockspan delete <name or id> - Delete a saved area
/blockspan clear-saved - Delete all saved areas

Measurements

Blockspan uses inclusive Minecraft-style measurements. If Point A and Point B are the two ends of a wall, both endpoint blocks are counted.

The overlay can show:

Point A and Point B coordinates
Length, width, and height
X/Y/Z delta
Straight-line distance
Center point
Total cuboid volume

Requirements FABRIC

Fabric Loader
Fabric API
Minecraft 26.1.2

Requirements FORGE:

Forge
Minecraft 26.1.2

Client-side only

Blockspan does not need to be installed on a server. It does not send packets, modify server data, or save anything into the world itself. Removing the mod will not damage or alter your saves.