How do I scale to a specific target size?

Set scale% = (target size ÷ original size) × 100, then enter that percentage.

3D Model Scale Calculator — Resize by Percentage

Q: Why does doubling the size use 8× the filament?

Volume grows with the cube of the linear scale: 2³ = 8.

Your inputs

Your result

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Enter your values to see the scaled dimension

Scaling a 3D model seems simple — increase the percentage in your slicer, get a bigger part. But the relationship between linear dimension and volume is non-linear in a way that surprises most 3D printing beginners: because volume is three-dimensional, scaling in all axes simultaneously causes material use to grow by the cube of the scale factor. A 20% scale increase leads to a 73% increase in material and print time. This calculator makes that relationship instantly visible before you commit to printing.

The formula, explained step by step

New dimension:
New size = original size × (scale% ÷ 100)
100 mm at 150%: 100 × 1.5 = 150 mm

Volume and material multiplier:
Multiplier = (scale% ÷ 100)³
At 150%: 1.5³ = 1.5 × 1.5 × 1.5 = 3.375× the material

At 200% scale, you get 2³ = 8× the material. At 50%, you get 0.5³ = 0.125× — an eighth of the material for a model at half size. This cubic relationship applies uniformly because the printer scales all three dimensions (X, Y, Z) simultaneously.

Scaling to a specific target dimension:
Scale% = (target dimension ÷ original dimension) × 100
To go from 80 mm to 60 mm: (60 ÷ 80) × 100 = 75%. Plug 75 into your slicer and the result is confirmed.

Scale factor vs. material multiplier quick reference

50% scale → 0.125× material (1/8th)
75% scale → 0.422× material (~42%)
90% scale → 0.729× material (~73%)
110% scale → 1.331× material (~33% more)
125% scale → 1.953× material (~95% more)
150% scale → 3.375× material (~238% more)
175% scale → 5.359× material (~436% more)
200% scale → 8.000× material (8×)
250% scale → 15.625× material
300% scale → 27.000× material (27×)

How to use this calculator

Find your original model dimension. Open your slicer (PrusaSlicer, Cura, OrcaSlicer, Bambu Studio) and check the model's current size. Most slicers show width × depth × height in the sidebar or object info. Pick any dimension that you want to track — usually the largest dimension for scale reference.
Enter the scale percentage. The percentage you plan to scale to in your slicer. 100% = original size. 150% = 50% larger. 75% = 25% smaller. This is the same value you enter in your slicer's scale field.
Read the new dimension. Confirms what the scaled size will be for that dimension.
Read the volume multiplier. This tells you how much more (or less) filament you'll use compared to the original. Multiply your slicer's current gram estimate by this multiplier to estimate the scaled print weight. Note: the multiplier is exact only for uniform scaling — if you scale each axis differently in your slicer, the calculation is more complex.

Real-world use cases for scale adjustment

Case 1: Scaling a cosplay prop to fit the wearer

A Mandalorian helmet downloaded from Thingiverse is modeled at 220 mm tall (a "medium" head size). The cosplayer's head requires 245 mm tall. Scale% = (245 ÷ 220) × 100 = 111.4%. Volume multiplier: 1.114³ = 1.383. If the original estimates 185 g of filament, the scaled version will need approximately 185 × 1.383 ≈ 256 g — an additional 71 g to fit properly. This also affects whether the model fits on the build plate, since all dimensions scale proportionally.

Case 2: Printing a miniature at different scales

A dungeon miniature is designed at 54 mm "heroic scale." To print at 28mm tabletop scale: 28 ÷ 54 = 0.519 scale, so 51.9% scale. Volume multiplier: 0.519³ = 0.140. If the heroic scale uses 12 g, the 28mm scale uses only 12 × 0.140 ≈ 1.7 g — and takes 7× less time. For batch printing miniatures, scaling down from designer scale to tabletop scale dramatically reduces material and time costs.

Case 3: Adjusting for fit tolerance

A phone case designed for an iPhone 15 is 2 mm too tight on all sides (the model's original is for a slim-fitting version). You need to scale up 3% to accommodate: 103% scale. Volume multiplier: 1.03³ = 1.093 — only 9.3% more material for a 3% linear scale increase. This is where the cubic relationship works in your favor — small dimensional adjustments have modest material cost impacts.

Case 4: Print farm scaling for sample vs. production

A product sample is printed at 75% scale for client approval before full production. Volume multiplier: 0.75³ = 0.422. If the full-scale version uses 95 g, the sample uses 95 × 0.422 ≈ 40 g — less than half the material and time. The client approves, and the farm scales to 100% for production. Using sample-scale prints for client approval is standard practice — this calculator confirms the material savings before printing the sample.

Case 5: Scaling up for wall thickness requirements

A functional bracket is designed at 60% of its intended size for a proof-of-concept. At 60% scale, wall thicknesses are only 0.6× the design spec — too thin for the nozzle diameter (0.4 mm minimum feature). Scaling to 100% gives proper wall thickness. Alternatively, redesign the model at the correct scale in CAD.

Minimum printable feature size at different scales

Scaling a model down doesn't just change the material amount — it changes which features are physically printable. With a 0.4 mm nozzle:

Minimum wall thickness: 0.4 mm (one extrusion width). Features narrower than this disappear at the slicer stage.
Minimum hole size: ~1 mm for functional (printable) holes; smaller holes print as solid or collapse.
Text legibility: Embossed text under 3 mm character height becomes illegible on most FDM printers. For readable text, keep character height above 5 mm at print scale.
Layer height and surface quality: At 0.2 mm layer height, scaling a 100 mm model to 50% means the same number of layers now cover 50 mm — relative surface quality (staircase effect) stays the same. Scaling up improves apparent surface quality for curved surfaces.

Before scaling down significantly, preview the sliced model in your slicer and check the "layer preview" to verify that all intended features are printing correctly.

Uniform vs. non-uniform scaling

This calculator assumes uniform scaling — the same percentage applied to all three axes simultaneously. This preserves the model's proportions and is by far the most common use case.

Non-uniform scaling (different % on X, Y, Z) stretches or compresses the model in specific directions. Use cases: correcting for dimensional inaccuracy in a specific axis (some printers are off by 0.5–1% on a single axis), adapting a model to fit a specific space (wider but not taller), or creating stylized stretched versions. For non-uniform scaling, use your slicer directly — each axis scales independently, and the volume multiplier is the product of all three scale factors: (X% ÷ 100) × (Y% ÷ 100) × (Z% ÷ 100).

How scaling interacts with print settings

Layer height stays constant: Scaling a model up doesn't automatically increase the number of layers; that depends on model height and your layer height setting. A 50 mm model at 0.2 mm layer height = 250 layers. Scaled to 100 mm: 500 layers at the same settings.

Wall count is absolute, not proportional: If you set 3 walls (perimeters), scaling the model from 100% to 200% doesn't give you 6 walls — still 3 walls, but each is the same 0.4 mm width. The wall-to-interior ratio changes significantly with scale, affecting strength per gram differently at different scales.

Support material scales cubically too: If a model at 100% needs 15 g of support material, at 150% scale it needs approximately 15 × 3.375 ≈ 51 g of support. For large print jobs, check your slicer's support estimate after scaling.

Scaling up large? Large prints benefit from high-speed printers and bigger nozzles (0.6 mm or 0.8 mm) which print faster and maintain quality at larger feature sizes. A 0.8 mm nozzle can print a 150% scale model 3–4× faster than a 0.4 mm nozzle with similar visual quality for items viewed at a distance.

Frequently asked questions

Why does doubling the size use 8× the filament?

Volume is three-dimensional. When you double every linear dimension (X, Y and Z all go to 200%), the volume — which is calculated as X × Y × Z — quadruples just from doubling two dimensions, then doubles again for the third: 2 × 2 × 2 = 8. This cubic relationship is fundamental to geometry and applies to any scaling in three dimensions. It's why a figurine printed at twice the size costs 8× more in material and takes roughly 8× longer to print (assuming the same layer height and infill).

How do I scale a model to a specific target size?

Divide the target dimension by the original dimension, then multiply by 100: scale% = (target ÷ original) × 100. Example: you want a model that's currently 85 mm tall to be 120 mm tall: scale% = (120 ÷ 85) × 100 = 141.2%. Enter 141.2% in your slicer's scale field. Verify by checking the displayed dimension in the slicer matches 120 mm.

Does scaling affect print quality?

Yes, in both directions. Scaling up improves apparent surface quality for curved surfaces (less visible layer lines relative to feature size) and makes fine details easier to print. Scaling down can push features below the minimum printable size — thin walls, fine text and small holes can disappear or fail. Always preview in your slicer after scaling to check: layer preview mode shows if all features are intact. If thin walls are disappearing, check if "thin walls" is enabled in your slicer settings.

Can I scale only one axis (for example, make it taller but not wider)?

Yes — most slicers have per-axis scaling. In PrusaSlicer: right-click the model → Scale → uncheck "Uniform scaling," then set X, Y, Z independently. In Cura: click the scale icon, disable the lock icon, then set each axis separately. In Bambu Studio/OrcaSlicer: similar per-axis controls in the scale panel. Non-uniform scaling changes the proportions of the model. The volume multiplier for non-uniform scaling is: (X% ÷ 100) × (Y% ÷ 100) × (Z% ÷ 100). This calculator assumes uniform scaling only.

Why is the scaled model larger than my build plate?

Build plate size is a hard limit. A model that fits at 100% may not fit after scaling. For printers with a 256 × 256 × 256 mm build volume (Bambu Lab P1S, Voron 2.4 300), a 200 mm model can't be scaled beyond 128% before hitting the limit. Solutions: print in multiple pieces and glue/bolt them together, rotate the model to use the diagonal of the build plate (the diagonal of a 256 mm square is 362 mm), or use a larger printer. Many designers publish "print-in-place" assembly versions of large models specifically to enable large-scale printing on standard printers.

How does scaling affect print time?

Print time scales approximately with the volume multiplier — roughly cubically for uniform scaling. A model that takes 3 hours at 100% scale will take approximately 3 × 3.375 ≈ 10 hours at 150% scale. However, the relationship isn't perfectly cubic because: print speed is constant regardless of model size, infill percentage is constant so infill line density increases proportionally, and some per-layer operations (Z-hop, layer changes) are fixed regardless of model size. In practice, scaling by 1.5× typically adds 3–4× the print time for most geometries.

Does scaling affect the structural strength of a part?

Counterintuitively, larger prints are often stronger in absolute terms but the same or weaker in specific strength (strength per gram). Walls remain the same absolute thickness (0.4 mm per perimeter), so they represent a smaller fraction of the total material as the model scales up. A part scaled to 200% doesn't have twice the wall thickness — it has the same wall thickness but proportionally less relative to the part size. For structurally critical scaled parts, increase wall count after scaling to maintain structural integrity, especially if scaling down below the original design's intended wall ratio.

What's the best way to scale a model for a specific material property?

Some materials shrink or warp after printing: ABS shrinks approximately 0.3–0.8% in all directions; Nylon shrinks 0.5–2% depending on humidity; PETG is mostly stable. To compensate for shrinkage, scale up by the inverse of the shrinkage rate. For ABS at 0.5% shrinkage: scale to 100.5% to get the correct final dimension. For a precisely fitting ABS part (e.g., a bracket that must fit a specific slot): scale to 101% and test-print a thin cross-section before the full print. Calibrate your specific filament's shrinkage on your printer before committing to precision parts.

How do I scale models from different unit systems?

CAD models from the US are often in inches; models from Europe in mm. If you import an inch-based model and your slicer is set to mm, the model will be 25.4× larger than intended. In Bambu Studio, right-click → "Fix model scale" and it detects the unit mismatch. In PrusaSlicer, there's a pop-up warning. If your model appears enormous (a 5-inch part showing as 127 mm — correct) or tiny (the model shows as 1 mm when it should be 25 mm), you likely have a unit mismatch. Scale by 25.4 (inches → mm) or 1/25.4 (mm → inches) to correct.

Can I use this calculator for resin printing?

Yes, the scaling formula is identical for resin and FDM. The volume multiplier applies to resin volume consumed. The key difference: at smaller scales, resin's higher detail resolution means you can print features at 50% scale that FDM cannot. Miniatures scaled to 50–75% are often better candidates for resin than FDM at any scale. Use the resin cost calculator with the scaled volume to estimate material cost: if the original 100% scale uses 8 ml of resin, at 75% scale it uses 8 × 0.422 ≈ 3.4 ml.

3D Model Scale Calculator