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Centimeters to Millimeters

1 Centimeter (cm) = 10Millimeter (mm)

By KAMP Inc. / UnitOwl · Last reviewed:

Result
10 mm
1 cm = 10 mm
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How Many Millimeters in a Centimeter?

One centimeter equals exactly 10 millimeters. To convert centimeters to millimeters, multiply by 10 — simply move the decimal point one place to the right. While this is the simplest possible metric conversion, it comes up in 3D printing when working with CAD software that uses centimeters as its default unit, such as certain configurations of Blender, SketchUp, or some engineering CAD programs. If you design a model in a CAD tool set to centimeters and export it without converting, your slicer will interpret the numbers as millimeters, making your model 10 times too small. Understanding this seemingly trivial conversion prevents a surprisingly common source of printing errors. It also helps when communicating with people who naturally measure objects in centimeters but expect the final model to behave correctly in a millimeter-based slicer and firmware environment. A quick unit check here can save an entire failed print. It is one of the simplest and most valuable import checks. In mixed CAD workflows, that small conversion is often the difference between a correctly sized part and a useless miniature.

How to Convert Centimeter to Millimeter

  1. Start with your measurement in centimeters.
  2. Multiply the centimeter value by 10 to get millimeters.
  3. Alternatively, move the decimal point one place to the right.
  4. The conversion is exact — centimeters and millimeters are both metric units.
  5. Common sizes: 1cm = 10mm, 5cm = 50mm, 10cm = 100mm, 20cm = 200mm, 25cm = 250mm.

Real-World Examples

Your Blender model is 5cm tall, but your slicer shows it as 5mm tall.
Blender exports the raw number (5). Your slicer interprets it as 5mm. You need to scale by 10x, or set Blender's export unit to millimeters. The correct height is 5 x 10 = 50mm.
A product design spec says the enclosure should be 12cm x 8cm x 3cm.
12 x 10 = 120mm, 8 x 10 = 80mm, 3 x 10 = 30mm. Enter these dimensions in your slicer. All three fit on most printer build plates.
You measured a replacement part with a ruler marked in centimeters and got 7.3cm long.
7.3 x 10 = 73mm. Enter 73mm in your CAD program. For a replacement part, measure multiple times and add appropriate tolerances.
A 3D model downloaded from a library appears 10 times too small in your slicer.
The model was likely designed in centimeters. Scale it by 1000% (10x) in your slicer. A 2cm part should become 20mm. Always check overall dimensions after importing.
A cosplay accessory should be 18.5cm long. What dimension should you set in a mm-based CAD tool?
18.5 x 10 = 185mm. Modeling it directly at 185mm keeps the slicer and printer workflow consistent from the start.

Quick Reference

Centimeter (cm)Millimeter (mm)
110
220
550
10100
25250
50500
1001,000
5005,000
1,00010,000

History of Centimeter and Millimeter

The centimeter was introduced as part of the metric system in 1795, defined as one hundredth of a meter. While the millimeter is the standard in 3D printing and precision manufacturing, the centimeter remains common in everyday measurements in many countries (height, fabric, furniture dimensions). The CGS (centimeter-gram-second) system of units was the dominant scientific system before being largely replaced by the SI system (meter-kilogram-second) in the 1960s. In CAD software, the default unit varies by program and region, which is the primary source of cm-to-mm confusion in 3D printing workflows.

Common Mistakes to Avoid

  • Exporting from a CAD program set to centimeters without converting to millimeters. The STL file format stores raw numbers without unit metadata. A 10cm cube exports as "10" and the slicer interprets it as 10mm — resulting in a part 10 times too small.
  • Confusing the scale factor. If your model is 10x too small, you need to scale by 1000% (not 10%). Slicers show scale as a percentage where 100% is no change. To multiply by 10, enter 1000%.
  • Not checking the default unit in your CAD software before starting a design. Blender defaults to meters (not cm or mm), Fusion 360 defaults to mm, and SketchUp can be set to either. Always verify before designing.
  • Trying to fix a 10x scale error by tuning printer steps, flow, or slicer percentages blindly. If a model was authored in cm and imported as mm, the real fix is correcting the source unit or scaling by exactly 10x.
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Frequently Asked Questions

Why do 3D printers use millimeters instead of centimeters?
Millimeters provide a convenient scale for 3D printing precision. Layer heights (0.1-0.3mm), nozzle diameters (0.4mm), and tolerances (0.1-0.2mm) are all easily expressed as simple decimals in mm. In centimeters, these would be 0.01-0.03cm, 0.04cm, and 0.01-0.02cm — awkward numbers with many leading zeros.
Which CAD programs default to centimeters?
Blender uses meters by default (so a "1 unit" object is 1mm in slicer interpretation if you export without adjusting). SketchUp can default to cm depending on template. Some versions of Rhino use cm. Always check Settings > Units before starting a model intended for 3D printing.
How do I avoid cm/mm confusion when sharing STL files?
Include the intended unit in the filename (e.g., "bracket_120mm.stl"). In the design notes, state "all dimensions in mm." If possible, include a calibration feature of known size (like a 10mm cube) so the recipient can verify scale after import.
How can I tell if a model imported 10 times too small?
Check the bounding-box size in the slicer. If an object that should be around 10cm appears as 10mm instead of 100mm, it was likely authored in centimeters and interpreted as millimeters. Scaling it to 1000% usually fixes the mismatch.
What should I do if a model imports exactly 10x too small?
Treat it as a unit mismatch first, not a calibration problem. Scale the model to 1000% in the slicer or go back to CAD and re-export in millimeters so the geometry and the slicer agree.
Quick Tip

Before your first print of any imported model, check its dimensions in the slicer. If a model that should be 10cm (100mm) shows up as 10mm, scale by 1000%. If it shows up as 100,000mm, the original was in meters — scale to 0.1%. Most slicers show the model bounding box dimensions, making this check quick and easy. Building this habit prevents wasted filament on incorrectly scaled prints.

Sources & References