3D Print Scale Calculator
Resize any model by scale factor or a target dimension, check it fits your bed, and see the real material and time cost — because volume grows with the cube of the scale.
Show instructions
1.Enter the model's current size
Type the original X, Y, and Z dimensions (in mm) from your slicer or model info. If you know the original filament weight or print time, add those too — the tool will scale them by the cube law so you get grams and hours, not just multipliers.
2.Choose how you want to resize
Pick one: enter a scale factor / percentage directly, enter a target dimension on one axis (the tool solves the factor and applies it to all three for uniform scaling), or enter your printer's build volume to get the largest scale that still fits the bed.
3.Read the dimensions, material, and time
You get the new X/Y/Z, the volume multiplier (s cubed) for filament, and an approximate time multiplier. Sanity-check the result against your spool and your patience, then re-slice in your slicer to confirm the exact grams and hours before you commit.
Material and print time scale with the cube of the factor — doubling a model’s size uses ~8× the filament. Time is approximate; infill, supports, and speed shift it.
Scaling a model in your slicer is one slider, but it hides a trap that catches almost everyone the first time. When you set the scale to 200%, every linear dimension — length, width, height — doubles. That part feels intuitive. What is not intuitive is what happens to the amount of plastic and the time on the printer: those track volume, and volume grows with the cube of the scale factor. Double the size and you do not use twice the filament. You use eight times the filament, and roughly eight times the hours. This calculator does that math for you so a quick "let's just print it bigger" doesn't quietly turn a 4-hour, 30-gram print into a 32-hour, 240-gram one.
There are three jobs this tool handles. First, resize by a scale factor and get every new dimension plus the volume (material) and approximate time multipliers. Second, resize to a target dimension — type the height or width you actually want, and it solves the scale factor and the rest of the box for you. Third, scale to fit your printer's bed: enter your build volume and it tells you the largest scale that still fits, so you stop discovering at slice time that the model is 12 mm too tall. The dimension math is exact geometry. The material multiplier is exact for a uniformly scaled solid. The time multiplier is honest about being an estimate — print time depends on infill, walls, supports, and speed, which we explain in the notes below.
The math
Let s = linear scale factor (e.g. s = 2.0 for 200%).\n\nNEW DIMENSIONS (exact):\n new_X = old_X x s\n new_Y = old_Y x s\n new_Z = old_Z x s\n\nSCALE FROM A TARGET DIMENSION (uniform scaling on one axis):\n s = target_dimension / original_dimension\n (e.g. want 150 mm tall from a 90 mm model: s = 150 / 90 = 1.667 -> 166.7%)\n\nSCALE TO FIT A PRINT BED (largest uniform scale that still fits):\n s_max = min( bed_X / model_X , bed_Y / model_Y , bed_Z / model_Z )\n (each axis must fit; the tightest axis sets the limit)\n\nMATERIAL / VOLUME MULTIPLIER (the cube law, exact for a uniformly scaled solid):\n volume_multiplier = s^3\n new_filament_grams = old_grams x s^3\n new_filament_length = old_length x s^3\n\n So s = 2 -> 2^3 = 8x material; s = 0.5 -> 0.125x (one eighth); s = 3 -> 27x.\n\nSURFACE AREA MULTIPLIER (exact):\n area_multiplier = s^2\n\nPRINT TIME MULTIPLIER (APPROXIMATE):\n time_multiplier is approximately s^3\n Time is dominated by the volume of material extruded (~s^3), but a portion of\n it (perimeter/wall and surface travel) scales nearer s^2. Treat s^3 as a close\n upper-ish estimate and re-slice for the real number.
Good to know
Material is exact; time is an estimate
For a model scaled uniformly, the volume multiplier of s^3 is exact, so the filament figure is trustworthy. Print time is not exact. It is dominated by the extruded volume (which scales s^3), but wall/perimeter and surface-travel moves scale closer to s^2, and your actual time shifts with infill density, wall count, layer height, supports, and speed. Use the time number to plan, then re-slice for the real value.
Scaling down is the same law in reverse
The cube law cuts both ways. Scale to 50% and you do not halve the plastic — you use one eighth of it (0.5^3 = 0.125). That is great for test prints: a quick 40% scale check costs about 6% of the material of the full part. Just watch small features and wall thickness, which can drop below what your nozzle can reliably print.
Uniform scaling assumed — check thin walls and clearances
This tool assumes you scale all three axes by the same factor, which preserves the shape. Scaling also multiplies wall thickness, holes, pins, and tolerances by s. A press-fit or threaded part that fit perfectly at 100% will usually need its clearances re-tuned after scaling, and a wall that was 0.8 mm becomes 0.4 mm at 50% — possibly too thin to print.
The bed-fit result is geometry, not orientation
Scale-to-fit uses the model's bounding box against your build volume on each axis. Rotating the model on the plate (e.g. printing a long part diagonally or laying a tall one on its side) can let a larger scale fit than the raw numbers suggest. Treat s_max as the safe, no-rotation answer and explore orientation in your slicer for more headroom.
FAQ
If I make a model twice as big, how much more filament does it use?
Eight times as much. Doubling the size (200% scale) doubles every linear dimension, but filament tracks volume, and volume scales with the cube of the scale factor: 2^3 = 8. A part that used 30 g at 100% will use about 240 g at 200%. This is the single most common surprise in scaling, and it is why the calculator shows the volume multiplier separately from the dimensions.
Does print time also scale by the cube of the scale factor?
Approximately, but not exactly. Most of your print time is spent extruding plastic, and the volume of plastic scales s^3, so time roughly follows the same curve. However, perimeter and surface moves scale closer to s^2, and infill, walls, supports, and speed all shift the result. Treat the s^3 time multiplier as a close planning estimate and re-slice the scaled model to get the true number.
How do I scale a model to an exact height or width?
Divide the target dimension by the original on that axis: s = target / original. For a 90 mm-tall model you want at 150 mm, s = 150 / 90 = 1.667, or 166.7%. Apply that same factor to all three axes for uniform scaling. The calculator does this and then fills in the other two dimensions and the material cost for you.
How do I scale a model to fit my printer's bed?
Compare your build volume to the model on each axis and take the smallest ratio: s_max = min(bed_X/model_X, bed_Y/model_Y, bed_Z/model_Z). The tightest axis sets the limit. If your bed is 220x220x250 mm and the model is 300 mm wide, the X axis caps you at 220/300 = 0.733, so 73% is the largest uniform scale that fits without rotating the part.
If I scale a model down to 50%, do I save half the filament?
No — you save far more. At 50% the volume drops to 0.5^3 = 0.125, so you use only about one eighth of the original filament and roughly an eighth of the time. This makes small-scale test prints extremely cheap. The trade-off is that fine details and thin walls also shrink by half and may fall below what your nozzle can print reliably.
Why does the material multiplier use volume instead of the spool length on the box?
Filament is extruded by volume, and a uniformly scaled solid changes volume by s^3. Whether you measure that in grams (volume x material density) or in meters of 1.75 mm filament (volume / cross-section area), both scale by the same s^3 factor. So you can multiply either your original weight or original length by s^3 and get the right answer.
Does scaling change wall thickness and tolerances?
Yes, and this matters. Uniform scaling multiplies everything by s, including wall thickness, hole diameters, pins, and clearances. A part with a snug press-fit at 100% will usually be too loose when scaled up and too tight when scaled down, and a 0.8 mm wall becomes 0.4 mm at 50%. Re-check fit-critical features and re-tune clearances after any significant scale change.
Should I scale in the slicer or in the original CAD/model?
For a quick uniform resize, scaling in the slicer is fine and fastest — the geometry math is identical. If you need to fix tolerances, change wall thickness independently of the overall size, or keep specific features at a fixed dimension, do it in CAD. The slicer scales everything proportionally; only the source model lets you scale some things and hold others constant.