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Convert Kilograms to Carats - Weight Converter

This converter converts a mass value expressed in kilograms (kg) to carats (ct). It is intended for quick, exact mathematical conversion when you have a numeric kilogram value and need the equivalent in carats.

The tool uses the defined unit relationship between the kilogram (SI base unit of mass) and the carat (a unit defined exactly as 0.2 grams). Guidance on measurement uncertainty, calibration, and legal metrology considerations is provided to help you use results appropriately.

Updated Nov 7, 2025

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Methodology

Unit definitions: one carat is defined as exactly 0.2 grams. One kilogram equals 1000 grams. The conversion is therefore a fixed mathematical relationship and does not require empirical measurement.

Best practice: perform conversions with sufficient significant figures for your use case, and when converting measured masses, account for measurement uncertainty and instrument calibration traceable to national standards (for example NIST or ISO/IEC 17025-accredited laboratories).

Worked examples

0.001 kg = 5 carats (0.001 × 5000 = 5).

0.5 kg = 2500 carats (0.5 × 5000 = 2500).

1 kg = 5000 carats (1 × 5000 = 5000).

Key takeaways

Converting kilograms to carats is an exact fixed-factor conversion: multiply kilograms by 5000 to get carats.

For measurements from physical scales, apply appropriate rounding and report measurement uncertainty. Use calibrated equipment traceable to national standards for legal or high-value applications.

Further resources

Expert Q&A

Why is the conversion exact?

The carat is defined exactly as 0.2 grams and the kilogram is an SI base unit (1000 grams per kilogram), so the mathematical relationship between kilograms and carats is exact and fixed.

How do I convert carats back to kilograms?

To convert carats to kilograms divide by 5000. Example: 2500 carats ÷ 5000 = 0.5 kg.

How many significant figures should I use?

Choose significant figures based on the precision of your measurement instrument. For digitally reported measured masses, match the instrument's display precision and include a statement of measurement uncertainty when required by protocol or regulation.

Do I need to calibrate my scale before converting?

Yes for measured masses. Calibration ensures traceability to national standards and reduces systematic error. Use calibration intervals and procedures consistent with ISO/IEC 17025 or your organization's quality management rules.

Are there legal or safety considerations?

For trade or legal metrology (e.g., selling gemstones by mass) follow applicable national regulations and OIML recommendations. For manual handling of heavy items refer to workplace safety guidance such as OSHA ergonomics and manual handling resources to prevent injury.

Sources & citations