How to scale a 3D print in Bambu Studio (and Bambu Handy)

To scale a 3D print in Bambu Studio, select the model, press S and type a percentage in the Scale row of the Object Operations panel. Typing 200 doubles every side and 50 halves it. Leave “uniform scale” ticked so the shape does not stretch. To hit an exact size, type it in the Size row instead, and the percentage follows.

Labels and shortcuts below were checked in Bambu Studio 2.8.2.61 (the public release from August 2026) and Bambu Lab’s wiki. On a Mac, read Ctrl as ⌘ and Alt as Option.

How do you scale a model in Bambu Studio?

Click the model on the plate, press S or click Scale on the top toolbar, and type a percentage in the Scale row of the Object Operations panel. 100% is the size the file came in at. Keep uniform scale ticked so X, Y and Z change together. Press Enter, then slice again.

The panel has five controls:

Control	What it does
Scale (%)	Size as a percentage of the imported file. With uniform scale on, typing in any one box sets all three.
Size (mm)	The model’s real measurements. Type the one you need and the percentage follows. Shows inches if Units is set to Imperial in Preferences.
uniform scale	Ticked by default. Untick it to stretch or squash one axis only.
Reset arrow	Appears at the end of the Scale row once the scale is not 100%. Click it to go back to 100%. Ctrl+Z undoes one step.
World / Object / Part coordinates	Sets which way X, Y and Z point. It only matters on a model you have rotated.

For an exact size, divide the size you want by the size the panel shows and multiply by 100. A figure 75 mm (2.95 in) tall that should stand 150 mm (5.91 in) tall needs 150 / 75 × 100 = 200%, or type 150 in the Z box of the Size row. The scale calculator does this math, including kit conversions such as 1:72 to 1:35.

If you know what one distance on the model should be, such as the gap between two holes, use the Measure tool instead. Measure the distance, click Edit to scale and type the correct length. Bambu Studio scales the whole model by that ratio.

Dragging the handles

With the Scale tool open, a box with handles surrounds the model. A tooltip shows the percentage as you drag.

• Corner handles (the four at the base) scale all three axes together.
• Side and top handles stretch one axis only.
• Shift while dragging moves in fixed 5% steps.
• Ctrl while dragging a side handle scales from that side only. The opposite face stays put.

Several objects, or one part of a model

Press Ctrl+A to select every object, or Ctrl+click to pick several, then type the percentage once. With a group selected, the Scale box always reads 100%, so the number you type multiplies their current size: typing 200 twice gives 400%. Press A (Arrange all objects) afterward if they crowd the plate.

To scale one part of a multi-part model, Alt+click it on the plate or click it in the object list. Part coordinates then appears in the menu, and the Scale and Size rows apply to that part alone.

Fixing a model imported in inches

A file drawn in inches opens 25.4 times too small, because Bambu Studio reads its numbers as millimeters. When a model’s volume is under 8 mm³, Bambu Studio asks on import: “The object from file … is too small, and maybe in meters or inches. Do you want to scale to millimeters?” Answer Yes and it multiplies the model by 25.4, or by 1,000 if it looks like meters.

If no prompt appears, right-click the model and choose Convert from inch (or Convert from meter). Restore to inch reverses the conversion. Typing 2540 in the Scale row gives the same size, since 25.4 × 100 = 2,540%.

How to scale up or scale down a 3D print in Bambu Studio

The steps are the same either way: above 100% makes the model bigger, below 100% makes it smaller. Only the checks afterward differ.

After scaling up: check it fits the build volume

A model that hangs over the plate or rises above the build height triggers this warning: “An object is laid over the boundary of plate or exceeds the height limit.” To find the largest size that fits, right-click the model and choose Scale to print volume. It scales the model evenly, up or down, until its tightest axis fills the build volume. Then it centers the model on the plate.

Worked example on an A1 mini, whose build volume is 180 × 180 × 180 mm (7.09 in each way):

1. The figure is 50 × 40 × 75 mm. You want it 9 in (228.6 mm) tall.
2. Scale: 228.6 / 75 × 100 = 304.8%. The height becomes 228.6 mm, 48.6 mm over the limit.
3. Largest that fits: 180 / 75 = 2.4, so 240%, giving 120 × 96 × 180 mm.

A model too tall to stand upright may fit lying on its side, or cut in two with the Cut tool (C).

After scaling down: thin walls and small holes

Every wall shrinks by the same factor. Bambu Lab’s wiki says a printed line is about as wide as the nozzle, 0.4 mm on the A1 mini’s included nozzle. A 1.2 mm wall at 30% becomes 0.36 mm, narrower than one line, so it may print with gaps or not at all. Slice and step through the layers in Preview to check.

Holes and pegs also shrink. A 5 mm hole at 50% becomes 2.5 mm, too small for its original screw or magnet.

Plastic and print time grow with the cube of the scale

Volume grows with the cube of the scale. At 200% every side doubles and a solid part holds 2³ = 8 times the plastic. At 50% it holds one eighth.

Scale	Each side	Solid volume
50%	× 0.5	× 0.125
75%	× 0.75	× 0.42
125%	× 1.25	× 1.95
150%	× 1.5	× 3.38
200%	× 2	× 8
300%	× 3	× 27

That cube applies exactly to a solid part. A sliced part scaled up weighs less than the cube suggests. Its walls and top and bottom layers keep their set thickness, so the shell grows roughly with the square of the factor and only the infill grows with the cube.

Slice again after scaling (Ctrl+R): the Preview lists the new filament weight and print time. To estimate before slicing, the print weight calculator works out grams for the new size with your walls and infill. The print time calculator estimates the hours.

How do you scale a print in Bambu Handy?

You can’t: Bambu Handy, up to version 4.3.0, has no scale setting. Bambu Lab’s guide to printing from the app lists the printer, plate, filament, copies and parts to print, but nothing that changes size. Scale the model in Bambu Studio on a computer, then send it to the printer. Handy can reprint it later from print history.

Bambu Handy’s release notes through version 4.3.0 (October 2026) add no scale option either. To print a MakerWorld model at a different size:

1. On a computer, sign in to Bambu Studio with the same Bambu Lab account as Handy. Bambu Lab’s wiki says the sign-in enables reprinting from history in the app.
2. Download the model’s 3MF or STL from MakerWorld and open it in Bambu Studio.
3. Scale it as above, slice, click Print plate and then Send.
4. Follow the print on Handy’s Device screen. To print it again at the same size, start it from print history in Handy.

Parametric MakerWorld models are a partial exception. Handy 3.19.0 (April 2026) added the Parametric Model Editor. If the designer made size one of the model’s settings, you can change it there.