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SnapScaleCalc

Scale workbench

Scale anything, and see everything that changes

Most scaling mistakes are not arithmetic mistakes. They happen because a resize changes more than the number you typed: the factor, the final percentage, the percentage change and the area and volume of the thing are four different answers to the same edit. This workbench shows all of them at once, from whichever of the five starting points matches your problem.
  • Exact rational engine
  • Factor · percent · size · area · volume
  • Runs in your browser

Choose what you are doing

Enter what you have and what you want. You get the exact factor, the percentage to type into a print dialog or slicer, the resulting size, and what happens to area and volume.

What you are scaling

Accepts 120, 4.75, 1/8 or 3' 7 1/2".

Scale by

The size the same feature should end up at. Units can differ from the start.

Derived from the unrounded factor as k² and k³.

Your answer

1.5×

Every length is multiplied by 1.5×, which is 150% of the original. 80 mm becomes 120 mm.

This is an enlargement: the result is larger than what you started with.

Before and after, to scaleOriginalScaled

Bar lengths are proportional to the calculated factor. Read the exact figures below.

Scale factor
1.5×

Exact: 3/2

Resize percentage
150%

Enter this in a print dialog or slicer

Reverse factor
0.666666…×

66.666666…% to undo it

Result
120 mm

120 mm

Equivalent ratio
1.5:1

Result : original, as a representative ratio

Difference
+40 mm

Original was 80 mm

Consequences of this factor

How length, area and volume change at this scale factor
MeasureMultiplierChange
Length (k)1.5×+50%
Area (k²)2.25×+125%
Volume (k³)3.375×+237.5%

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: 80 mm = 80 mm
  • Target measurement: 120 mm = 120 mm

Formula

k = target ÷ original

k = 120 mm ÷ 80 mm

k = 1.5× = 150%

Derived effects

  • Area (k²): 2.25×
  • Volume (k³): 3.375×
  • Result size: 80 mm × k = 120 mm

Exact calculation state: 3/2 — displayed values are formatted from this fraction, never re-used after rounding.

Calculated by SnapScaleCalc from the values entered. Methodology

Every calculator on this site

Each of these is the same engine with a different starting point and a different emphasis. Pick the group that matches the words you would use for your problem.

Learn scaling

The calculators give you the numbers. These guides explain why scaling behaves the way it does, and how to tell a correct result from a plausible one.

Explore all scaling guides — six illustrated guides covering notation, growth, conversion, fit, printing and verification.

What else changes when you resize something

The example above takes 80 mm to 120 mm. That single edit produces four separate readings, and the last one is the one that surprises people.

Resize factor — 1.5×

The multiplier applied to every length. It is the quantity the engine actually holds; everything else on the page is derived from it, unrounded.

Final percentage — 150%

The same factor written as a share of the original. This is the figure a print dialog, copier or slicer wants: the size to end up at, not the amount to add.

Percentage change — +50%

How much was added, relative to the original. It differs from the final percentage by exactly 100 points, which is why “scale to 150%” and “increase by 150%” land on different objects.

Area 2.25× and volume 3.375×

Area follows the factor squared, volume the factor cubed. A part that looks half again as big encloses more than three times the material — the reason a modest resize wrecks weight, filament and cost estimates.

Every workflow above reports the same four readings, plus the limits that apply to it — fit results are bounding-box geometry, volume assumes a solid uniform shape, and reference scales are compared rather than applied. The definitions, formulas and rounding policy are set out once on the methodology page.