Millimeters to Centimeters Converter — Convert mm to cm (Exact: cm = mm ÷ 10)
Accurate millimeters (mm) to centimeters (cm) converter using the exact SI relationship 1 cm = 10 mm. Built for fabrication, 3D printing, PCB layout, apparel & fabric, product specs, education, and DIY. Includes exact formula, step-by-step examples, precision guidance, expanded quick tables, and in-depth FAQs.
Exact factor: 1 cm = 10 mm ⇒ cm = mm ÷ 10. See all free length converters.
About Millimeters to Centimeters Conversion
The millimeter (mm) is the workhorse of precision fabrication—CNC machining, 3D printing, electronics, and mechanical drawings—because it aligns with tight tolerances and avoids fractional decimals. The centimeter (cm) improves readability for consumer contexts such as furniture, garments, packaging, and DIY. Converting millimeters to centimeters lets you keep canonical measurements in mm for manufacturing while presenting clean, scannable values in cm for customers and stakeholders.
Because the relationship is exact—1 cm = 10 mm—you can safely compute at full precision in millimeters, aggregate or scale values, and convert to centimeters at the edge. This practice prevents small rounding errors from compounding across BOMs, labels, and CSV exports.
If you also support imperial displays, keep those as separate tools (inches ↔ mm, inches ↔ cm). Each page provides its own constants, examples, and rounding guidance so teams don’t mix unit families accidentally.
Millimeters to Centimeters Formula
Exact relationship
Use either expression:
cm = mm ÷ 10
// reverse
mm = cm × 10Example:
125 mm ÷ 10 = 12.5 cmRelated Length Converters
What is a Millimeter (mm)?
A millimeter is 1/1000 of a meter. It’s the default unit in most CAD/CAM systems, slicers, and mechanical prints, offering whole-number clarity for small features, holes, and fits. Using mm reduces the need for fractional decimals that are common in centimeters or inches when tolerances are tight.
What is a Centimeter (cm)?
A centimeter is 1/100 of a meter. It’s ubiquitous in retail and household contexts—furniture dimensions, size charts, and DIY instructions—because the numbers are easy to read and compare at a glance. Many teams present cm to end users while keeping mm canonical in storage for analysis and manufacturing.
Step-by-Step: Converting mm to cm
- Read the length in millimeters (mm) from your drawing, caliper, or spec.
- Divide by 10 to convert to centimeters (cm).
- Round once at display time (e.g., 1–2 decimals for consumer pages; match instrument resolution for QA).
Example walkthrough:
Input: 1 mm
Compute: 1 ÷ 10 = 0.1 cm
Output: 0.1 cm (UI)Common Conversions
Everyday quick checks (mm → cm)
| mm | cm | mm | cm |
|---|---|---|---|
| 1 | 0.1 | 5 | 0.5 |
| 10 | 1.0 | 12 | 1.2 |
| 25 | 2.5 | 50 | 5.0 |
| 75 | 7.5 | 100 | 10.0 |
| 125 | 12.5 | 150 | 15.0 |
| 200 | 20.0 | 250 | 25.0 |
| 300 | 30.0 | 500 | 50.0 |
| 750 | 75.0 | 1000 | 100.0 |
Precision, Rounding & Significant Figures
Operational rounding
Use whole millimeters internally for fabrication and CAM pipelines; present centimeters with one or two decimals for consumer UIs. Store raw values exactly and round once on output so dashboards, BOMs, PDFs, and exports line up.
Consistent documentation
Name fields clearly (e.g., length_mm, length_cm) and include a methods note: “Exact: 1 cm = 10 mm; cm = mm ÷ 10; mm = cm × 10. Round once at presentation.” This prevents confusion when multiple systems interact.
Where This Converter Is Used
- 🛠️ Fabrication & machining: Specs authored in mm; consumer documentation in cm.
- 🧩 3D printing & CAD: Models and slicers default to mm; storefronts show cm for readability.
- 🔌 Electronics: PCB footprints, pad sizes, and housings validated in mm and summarized in cm.
- 🧵 Apparel & fabric: Pattern pieces in cm for readability; seam allowances and tolerances in mm.
- 📦 Product specs: Marketing cards in cm; engineering drawings and QA in mm.
Quick Reference Table
Common centimeter values (cm → mm)
| cm | mm | cm | mm |
|---|---|---|---|
| 0.1 | 1 | 0.5 | 5 |
| 1.0 | 10 | 1.2 | 12 |
| 2.5 | 25 | 5.0 | 50 |
| 7.5 | 75 | 10.0 | 100 |
| 12.5 | 125 | 15.0 | 150 |
| 20.0 | 200 | 25.0 | 250 |
| 30.0 | 300 | 50.0 | 500 |
| 75.0 | 750 | 100.0 | 1000 |
Frequently Asked Questions
What is the exact formula to convert millimeters to centimeters?
Use the SI decimal relationship: one centimeter equals exactly ten millimeters. To convert mm → cm, divide by 10: cm = mm ÷ 10. The inverse is mm = cm × 10. Because this mapping is exact—not approximate—results remain consistent across calipers, CAD drawings, slicers, PDFs, and CSV exports.
When should I present centimeters instead of millimeters?
Use centimeters when whole-number readability helps humans scan specs—think furniture listings, garment sizing, and DIY guides. Millimeters shine in fabrication where fine tolerances matter. A common pattern is to store canonical values in millimeters (or meters), then derive cm for consumer-facing UI.
How many decimals should I show for mm → cm?
Centimeters are larger, so one or two decimals typically suffice for consumer pages (e.g., 12.3 cm). For QA and inspection, match your instrument’s resolution. Keep internal precision high and round once at presentation to prevent drift between tables, PDFs, and exports.
Do millimeters and centimeters measure linear length only?
Yes—mm and cm are linear length units. For area use mm² or cm²; for volume use cm³ or mL. Length-to-area/volume conversions require geometry and should be handled with dedicated calculators to avoid unit-family mixups.
How can I avoid double-rounding and unit mix-ups?
Centralize conversions in a single utility, compute at full precision, and round once at output. Label columns with explicit units (e.g., length_mm, length_cm). Maintain a small regression set of known pairs (like 125 mm = 12.5 cm) and test both directions to catch regressions early.
Can I convert inches or feet to centimeters on this page?
This tool focuses on millimeters ↔ centimeters. For imperial conversions, use the dedicated pages (e.g., inches ↔ cm, inches ↔ mm, feet ↔ meters). Keeping pairs isolated ensures each page shows the exact factor, worked examples, and appropriate rounding guidance for that pair.
What’s a good QA checklist for 3D printing and CNC?
Verify your CAD model units (mm vs. inches), confirm slicer/CAM settings, and print/cut a calibration part with known edges (e.g., 20 mm cube or gauge). Add unit tests for boundary values (0.1 cm = 1 mm, 12.5 cm = 125 mm) and validate both directions to prevent subtle rounding errors.
Why are my summed totals slightly off after converting?
Rounding accumulates across many segments. Sum at full precision in a canonical unit (often millimeters), then convert to centimeters and round once for the final display. This keeps purchase orders, cut sheets, and inspection reports consistent across systems.
How should I name fields in databases and exports?
Use explicit, unit-suffixed fields like length_mm and length_cm. Include a methods note in documentation: “Exact: 1 cm = 10 mm; cm = mm ÷ 10; mm = cm × 10; round once at presentation.” Clear naming prevents ambiguity when teams collaborate with vendors.
Tips for Working with Millimeters & Centimeters
- Keep SI canonical (often mm for fabrication; m for engineering); compute centimeters at the edges for UI.
- Publish a single rounding policy and apply it consistently across BOMs, PDFs, labels, and exports.
- Separate length tools from area/volume calculators to avoid unit-family mixups in specs and contracts.