How to Scale Miniatures in Chitubox & Lychee Slicer (Without Messing Up the Base)

If your STL file has an X-axis of 30mm, that is exactly 1.18 inches wide. This unit confusion — mixing millimetres and inches — is the most common mistake people make when scaling miniatures in slicer software, and it’s the one that taught me to never trust an import at face value.

The first time a file imported into Chitubox as a grain of rice, I spent an hour convinced the slicer was broken. It wasn’t. The sculptor had exported in inches, and my slicer was dutifully reading inches as millimetres. The fix took one number: scale everything up by 2540%. Since then I’ve developed a full routine that works in both Chitubox and Lychee every time, including how to scale a model without distorting the base.

The Golden Rule: Lock The Aspect Ratio

Before you type any number into a scale field, find the chain link icon and click it. When the chain is locked, changing one axis automatically updates the other two. This is how you avoid ending up with a miniature that looks like it was stepped on. I learned this one from a print that came off the plate looking like it had been through a hydraulic press — one axis at 114%, the others at 100%.

Slicer	Where to find the lock
Chitubox	Transform panel → Scale section → chain icon next to X/Y/Z
Lychee	Transform panel → Uniform scaling toggle (looks like a chain or a percentage sign with arrows)

Scaling in Chitubox

Chitubox is what I use for most of my proxy slicing. Here is the exact sequence I run:

1. Import your STL (File → Import → STL)
2. Select the model — click it in the viewport
3. Open the Transform panel (press T or click the Transform icon on the left toolbar)
4. Lock the aspect ratio — click the chain icon so it shows as connected
5. Type your percentage in the Scale X field — for a 28mm → 32mm conversion, enter 114.3
6. Check the height — the Z field should show the new height in mm
7. Click Apply (the checkmark) to confirm

Pro Tip: Scale Without Scaling the Base

If your miniature has an integral base that you do not want to scale, listen closely, because I ruined a hero’s scenic base this way once:

1. Before importing, use MeshLab or Blender to separate the base from the model
2. Import both pieces separately
3. Scale only the miniature body, leave the base at 100%
4. Merge them back together or print them as separate pieces and glue after

This is a common ask in the miniature printing community — a 32mm hero should not end up standing on a comically oversized 40mm base just because you scaled the whole model up. Trust me, nothing kills a good print faster than a base that dwarfs the model standing on it.

How to Measure Models in Chitubox

Before you type a single percentage, you need to know what you’re starting from. Measuring a model in Chitubox takes about three seconds:

1. Select the model in the viewport
2. Open the Transform panel (press T)
3. Read the X/Y/Z fields — Chitubox shows the current dimensions in millimetres, and those same fields double as the scale inputs

The number that matters for scale is the Z-axis — that’s the height. Select your model, look at the Z field, and you instantly know its current height in mm. That’s the source number for every conversion you type in.

Here is the catch I hit constantly: which height counts depends on how the sculptor measured it. Gaming scales like 28mm and 32mm measure to eye level, so a true 32mm model usually reads 34-35mm on the Z-axis once you include the forehead, hair, or helmet. If you measure a “32mm” model and see 34.5mm, that is not a mistake — that is eye level plus skull. If you have an unlabeled sculpt, print the scale reference bar and measure it in your slicer, and the reference library notes which measurement each scale uses.

A quick sanity check before you scale: a 28-32mm miniature should be roughly the height of your thumb. If the Z-axis shows a grain of rice instead, the file was exported in inches — jump down to the Lychee units section for the fix.

Scaling in Lychee Slicer

Lychee is my go-to for bigger batch prints because the interface feels faster. The steps mirror Chitubox:

1. Import your STL (the plus icon or drag-and-drop)
2. Select the model in the 3D viewport
3. Open the Transform panel (right sidebar, looks like a move/scale/rotate icon)
4. Enable uniform scaling — click the lock or chain icon
5. Enter your percentage — Lychee shows the scale as a multiplier, so 114.3% can be entered as either 114.3% or 1.143
6. Confirm — Lychee applies changes automatically

Lychee also shows you the real-world dimensions of the model in mm, so you can sanity-check your scale. A 32mm model should measure approximately 32mm in the Z-axis (plus or minus the base thickness). I always glance at that Z value before slicing — it has caught more mistakes than I care to admit.

How to Change Units in Lychee Slicer

Lychee works in millimetres out of the box, and most of the time you never need to touch the unit setting — model dimensions, the Transform panel, and the print bed all display in mm. But when you import STLs from a sculptor who exported in inches, you have two options:

Option 1: Change the display unit. Open Settings (or Preferences, depending on your Lychee version) and look for the unit selector next to the measurement readout. Switching it to inches only changes how Lychee displays dimensions — it does not rescale your model. I leave mine on millimetres and never think about it.

Option 2: Fix an inch-exported model — the one that actually matters. An inch file imports looking tiny because Lychee reads each inch as a millimetre. Don’t hunt for a hidden “import unit” toggle; just select the model, open Transform, enable uniform scaling, and enter 2540% (25.4 × 100). That converts inches to millimetres in a single step. Once it’s scaled, the Transform panel shows the real dimensions in mm so you can confirm the height before slicing.

Unit confusion is exactly why I check the Z-axis after every import: if a “32mm” hero imports at 32mm it’s good to go, and if it lands at 1.2mm you know precisely what happened.

When to Use mm vs Inches

Slicers display model dimensions in millimetres by default. If your STL was exported in inches, it will import looking either tiny (an inch-miniature showing as 1.2mm tall) or enormous (a mm-miniature showing as 25 feet tall).

Quick rule of thumb: A 28-32mm miniature should be roughly the height of your thumb. If it comes in looking like a grain of rice, it was likely exported in inches. Scale everything up by 2540% (25.4 × 100) to convert inches to millimetres.

Chitubox Unit Conversion Helper

If your file’s X-axis shows as, for example, 30mm:

Measurement	Value
Millimetres	30 mm
Inches	1.18 in
Scale to 32mm (from 28mm)	114.3%
Scale to 35mm (from 28mm)	125.0%

Use the STLACCESS scale engine to calculate any conversion, or browse the reference library for pre-calculated percentages. I use both constantly — that’s the whole reason I built them.

Common Mistakes to Avoid

These are the mistakes I’ve personally made, so you don’t have to:

• Forgetting to lock the aspect ratio — results in a squashed or stretched miniature. My hydraulic-press print was the teacher here.
• Scaling the base with the model — makes the base look wrong for the game system. Separate it first.
• Distinguishing between eye-level and top-of-head — 28mm refers to eye level; ratio scales like 1:56 are top-of-head. The scale reference has notes for each
• Skipping the test print — I always print one test piece and measure it with my PARKSIDE calipers before committing to a full squad. The STL scale calculator has a shrinkage compensation toggle for filaments that shrink more than the usual 0.2-0.5%