3D print scale
3D print scale calculator
1. Slicer percentage
Enter the dimension as it is in the model file and the dimension you want on the finished print.
What you are scaling
Accepts 120, 4.75, 1/8 or 3' 7 1/2".
Enter the number only, for example 150.
Derived from the unrounded factor as k² and k³.
Your answer
137.5%
This is an enlargement: the result is larger than what you started with.
Bar lengths are proportional to the calculated factor. Read the exact figures below.
- Scale factor
- 1.375×
- Resize percentage
- 137.5%
- Reverse factor
- 0.727272…×
- Result
- 55 mm
- Equivalent ratio
- 1.375:1
- Difference
- +15 mm
Exact: 11/8
Enter this in a print dialog or slicer
72.727272…% to undo it
55 mm
Result : original, as a representative ratio
Original was 40 mm
Consequences of this factor
| Measure | Multiplier | Of original | Change |
|---|---|---|---|
| Length (k) | 1.375× | +37.5% | |
| Area (k²) | 1.890625× | +89.0625% | |
| Volume (k³) | 2.599609…× | +159.960937…% |
Area and volume figures are geometric consequences of the length factor. They describe a solid, uniformly scaled shape — not hollow parts, infill, wall thickness or material behaviour.
How this was calculated
Inputs
- Starting measurement: 40 mm = 40 mm
- Percentage: 137.5% (scale to)
Formula
k = percentage ÷ 100
k = 137.5 → 11/8
k = 1.375× = 137.5%
Derived effects
- Area (k²): 1.890625×
- Volume (k³): 2.599609…×
- Result size: 40 mm × k = 55 mm
Exact calculation state: 11/8 — displayed values are formatted from this fraction, never re-used after rounding.
Calculated by SnapScaleCalc from the values entered. Methodology
“Scale to” and “increase by” are not the same
At 137.5%, scaling to that percentage gives 55 mm, while increasing by it gives 95 mm. The selected reading is used above.
2. Build volume check
Enter the model's bounding box and your printer's usable build volume. Rotation here means 90° axis swaps only — check your slicer's own preview before committing.
Object and space
Object
Build volume
Tests every axis permutation and keeps the unrotated orientation on a tie.
For example 1.5 to check whether 150% still fits.
Your answer
416.666666…%
Bounding-box geometry only: no allowance for clearance, tolerance, handling, fixings or how the object is moved into the space.
- X166.6666… mm of 220 mm
- Y166.6666… mm of 220 mm
- Zlimit250 mm of 250 mm
The bar track is the available envelope. The axis that fills it completely is the one that runs out of room first.
- Maximum factor
- 4.166666…×
- Limiting dimension
- Z
- Scaled X
- 166.6666… mm
- Scaled Y
- 166.6666… mm
- Scaled Z
- 250 mm
Exact: 25/6
The dimension that runs out of room first
Available 220 mm
Available 220 mm
Available 250 mm
| Axis | At max scale | Available | Clearance |
|---|---|---|---|
| X | 166.6666… mm | 220 mm | 53.3333… mm |
| Y | 166.6666… mm | 220 mm | 53.3333… mm |
| Z | 250 mm | 250 mm | 0 — this axis is the limit |
How this was calculated
Inputs
- Object X: 40 mm
- Object Y: 40 mm
- Object Z: 60 mm
- Space X: 220 mm
- Space Y: 220 mm
- Space Z: 250 mm
- Rotation: not allowed
Formula
k_max = min(available_axis ÷ object_axis) across all axes
X→X: 5.5× Y→Y: 5.5× Z→Z: 4.166666…×
k_max = 4.166666…× (416.666666…%), limiting axis Z
Exact calculation state: 25/6 — displayed values are formatted from this fraction, never re-used after rounding.
Calculated by SnapScaleCalc from the values entered. Methodology
Assumptions in this calculation
- The object and the space are both treated as rectangular bounding boxes.
- Scaling is uniform: every axis is multiplied by the same factor.
- No clearance, tolerance or access allowance is subtracted — reduce the available space yourself if you need it.
- The object keeps its entered orientation.
Volume multipliers are geometry, not material
The k³ figure describes a solid, uniformly scaled shape. Filament or resin use depends on wall count, infill density, supports and orientation, so take the material estimate from your slicer after scaling — not from the volume multiplier.
How this calculation works
A slicer's scale box is uniform and applies to the model as loaded, so the percentage from step 1 lands on all three axes at once: the 40 × 40 × 60 mm example above becomes 55 × 55 × 82.5 mm at 137.5%. Measure the model dimension in the slicer's own object panel rather than from the source drawing — exported STL and 3MF files often carry a unit or orientation change already.
The build check is bounding boxes, not the mesh
Step 2 compares the model's bounding box against the usable build volume, axis by axis, and reports the smallest of those ratios as the largest scale that still fits, plus the axis that ran out first. Rotation is limited to 90° axis swaps: laying a tall part on its side is often what makes it fit, and the check will find that orientation, but it cannot evaluate an arbitrary tilt or nest a concave shape into free space around the gantry.
Print time follows area, material follows volume
Shell time tracks surface area (k²) while solid material tracks volume (k³), which is why a small percentage feels expensive: taking a 28 mm miniature to 32 mm is only 114%, but 48% more enclosed volume and a noticeably longer print. Those are geometric figures — take the filament or resin estimate from your slicer after scaling, since wall count, infill and supports dominate the real number. If you need percentage notation explained rather than applied, that belongs on the scale percentage calculator.
What this does not tell you
This is geometry. It does not know your nozzle diameter, layer height, minimum feature size, support requirements, shrinkage or the mechanical demands on the part. Scaling down takes walls, pins and holes below printable limits; scaling up magnifies warping, adhesion problems and print time.
Functional parts — threads, clips, press fits, gears, anything load-bearing — do not survive uniform scaling. Threads and fasteners follow their own standards, and strength does not scale with volume. Re-model rather than re-scale where fit or load matters.
Questions people ask about this
- What percentage do I type into my slicer?
- The “scale to” percentage: the target dimension divided by the model dimension, times 100. Scaling a 40 mm model to 55 mm is 137.5%.
- Will scaling to 200% use eight times the filament?
- Only for a solid part. Doubling every dimension multiplies geometric volume by eight, but a hollow print with fixed wall thickness and sparse infill uses far less than that. Use your slicer's estimate for material, and this page for geometry.
- Does the part still fit my printer?
- Enter the model dimensions and your build volume in the fit check below. It returns the largest uniform scale that stays inside the build area and which axis runs out first.
- Why did my scaled-down part fail to print?
- Wall thickness, embossed detail and small holes scale with everything else. Below roughly two nozzle widths a wall stops printing reliably, and no percentage fixes that — the model has to be edited.