1. Core Unit System

Metric System

• Base Units: Derived from the International System of Units (SI), with core units including:
  • Length: Millimeter (mm), centimeter (cm), meter (m)
  • Thread Pitch: Millimeters (mm) – distance between adjacent threads (e.g., M10×1.5 means 10mm diameter, 1.5mm pitch)
• Decimal-based: All units are scaled by powers of 10 (e.g., 1m = 100cm = 1000mm), simplifying calculations and conversions.

Imperial (US Customary) System

• Base Units: Originated from historical British measurements, with core units including:
  • Length: Inch (in), foot (ft), yard (yd) (1ft = 12in, 1yd = 3ft)
  • Thread Pitch: Threads Per Inch (TPI) – number of threads per inch (e.g., 1/4"-20 UNC means 1/4-inch diameter, 20 threads per inch)
• Fractional Scaling: Lengths are often expressed as fractions (e.g., 3/8in, 5/16in) instead of decimals, making conversions less intuitive.

2. Origin & Global Adoption

Metric System

• Origin: Developed in France in the late 18th century, designed for universal standardization.
• Global Use: Adopted by over 95% of countries worldwide, including all EU nations, China, Japan, Germany, and most industrialized economies.
• Industry Standards: Dominates international manufacturing standards such as ISO (International Organization for Standardization), DIN (German Institute for Standardization), and GB (Chinese National Standards).

Imperial (US Customary) System

• Origin: Evolved from medieval British units, with minor variations between UK Imperial and US Customary (e.g., gallon volume differs).
• Key Users: Primarily the United States, United Kingdom (for legacy applications), Canada (hybrid use), and some Caribbean nations.
• Industry Standards: Used in standards like ANSI (American National Standards Institute), ASME (American Society of Mechanical Engineers), and BSW (British Standard Whitworth) for traditional industries.

3. Application in Fasteners & Industrial Products

Metric Fasteners

• Designation: Marked with "M" (metric) followed by diameter and pitch (e.g., M8×1.25, M12×1.75).
• Common Sizes: Diameters range from M1 to M64+; pitch classifications include coarse (ISO metric coarse, UNC equivalent) and fine (ISO metric fine, UNF equivalent).
• Use Cases: Global manufacturing (automotive, machinery, electronics, construction), export-oriented products, and cross-border projects.

Imperial Fasteners

• Designation: Based on diameter (fractional or decimal inches) and thread type (e.g., 1/2"-13 UNC, 3/8"-24 UNF, 5/16"-18 UNEF).
• Thread Types:
  • UNC (Unified National Coarse): For general-purpose applications.
  • UNF (Unified National Fine): For high-precision or high-load scenarios.
  • UNEF (Unified National Extra Fine): For thin materials or tight spaces.
• Use Cases: US/UK domestic manufacturing (construction, automotive aftermarket, legacy equipment), replacement parts for older machinery, and North American-specific projects.

4. Key Practical Differences for International Trade

5. Critical Notes for Cross-Border Business

1. Customer Regional Preference:
   • European, Asian, and African buyers typically require metric sizes.
   • North American (US/Canada) and UK buyers may specify imperial sizes for domestic use.
2. 

   뉴스 세부 정보
   집 > 뉴스 >

   회사 뉴스-DIFFERENCES BETWEEN METRIC AND IMPERIAL(US CUSTOMARY) SIZES

   사건

   뉴스

   사건

   DIFFERENCES BETWEEN METRIC AND IMPERIAL(US CUSTOMARY) SIZES

   2025-12-22

   Metric and Imperial (often referred to as US Customary in North America) are two distinct measurement systems widely used in global manufacturing, engineering, and international trade. Understanding their key differences is critical for product selection, cross-border business, and avoiding compatibility issues—especially for fasteners (e.g., bolts, nuts, screws) and industrial components. Below is a detailed comparison:

   1. Core Unit System

   Metric System

   • Base Units: Derived from the International System of Units (SI), with core units including:
     • Length: Millimeter (mm), centimeter (cm), meter (m)
     • Thread Pitch: Millimeters (mm) – distance between adjacent threads (e.g., M10×1.5 means 10mm diameter, 1.5mm pitch)
   • Decimal-based: All units are scaled by powers of 10 (e.g., 1m = 100cm = 1000mm), simplifying calculations and conversions.

   Imperial (US Customary) System

   • Base Units: Originated from historical British measurements, with core units including:
     • Length: Inch (in), foot (ft), yard (yd) (1ft = 12in, 1yd = 3ft)
     • Thread Pitch: Threads Per Inch (TPI) – number of threads per inch (e.g., 1/4"-20 UNC means 1/4-inch diameter, 20 threads per inch)
   • Fractional Scaling: Lengths are often expressed as fractions (e.g., 3/8in, 5/16in) instead of decimals, making conversions less intuitive.

   2. Origin & Global Adoption

   Metric System

   • Origin: Developed in France in the late 18th century, designed for universal standardization.
   • Global Use: Adopted by over 95% of countries worldwide, including all EU nations, China, Japan, Germany, and most industrialized economies.
   • Industry Standards: Dominates international manufacturing standards such as ISO (International Organization for Standardization), DIN (German Institute for Standardization), and GB (Chinese National Standards).

   Imperial (US Customary) System

   • Origin: Evolved from medieval British units, with minor variations between UK Imperial and US Customary (e.g., gallon volume differs).
   • Key Users: Primarily the United States, United Kingdom (for legacy applications), Canada (hybrid use), and some Caribbean nations.
   • Industry Standards: Used in standards like ANSI (American National Standards Institute), ASME (American Society of Mechanical Engineers), and BSW (British Standard Whitworth) for traditional industries.

   3. Application in Fasteners & Industrial Products

   Metric Fasteners

   • Designation: Marked with "M" (metric) followed by diameter and pitch (e.g., M8×1.25, M12×1.75).
   • Common Sizes: Diameters range from M1 to M64+; pitch classifications include coarse (ISO metric coarse, UNC equivalent) and fine (ISO metric fine, UNF equivalent).
   • Use Cases: Global manufacturing (automotive, machinery, electronics, construction), export-oriented products, and cross-border projects.

   Imperial Fasteners

   • Designation: Based on diameter (fractional or decimal inches) and thread type (e.g., 1/2"-13 UNC, 3/8"-24 UNF, 5/16"-18 UNEF).
   • Thread Types:
     • UNC (Unified National Coarse): For general-purpose applications.
     • UNF (Unified National Fine): For high-precision or high-load scenarios.
     • UNEF (Unified National Extra Fine): For thin materials or tight spaces.
   • Use Cases: US/UK domestic manufacturing (construction, automotive aftermarket, legacy equipment), replacement parts for older machinery, and North American-specific projects.

   4. Key Practical Differences for International Trade

   Aspect	Metric System	Imperial System
   Conversion Complexity	Simple (decimal scaling: 1mm = 0.03937in)	Complex (fraction-to-decimal conversions: 1/4in = 6.35mm)
   Compatibility	No direct interchangeability with imperial parts (threads, dimensions, and tolerances differ).	Cannot be mixed with metric fasteners (e.g., an M10 bolt will not fit a 3/8"-16 nut).
   Tolerance Standards	ISO tolerance classes (e.g., 6H/6g for threads)	ANSI/ASME tolerance classes (e.g., 2A/2B for threads)
   Cost & Availability	Widely available globally; lower production costs for mass-market products.	Limited availability outside US/UK; higher costs for custom or niche imperial parts.

   5. Critical Notes for Cross-Border Business

   1. Customer Regional Preference:
      • European, Asian, and African buyers typically require metric sizes.
      • North American (US/Canada) and UK buyers may specify imperial sizes for domestic use.
   2. 빠른 링크

      집 회사 소개 상품 적용 뉴스 사건 문의하기

      빠른 연락

      주소

      중국 젠장 주 닌보 시의 인저우 구 우시앙 시의 루펜 산업단지 1호

      Tel

      +86--18658229310

      이메일

      amylin@ybfasteners.com

      우리 뉴스레터

      할인 및 더 많은 정보를 얻기 위해 뉴스레터에 가입하십시오.

      이메일 보내기
      개인 정보 정책 |  사이트맵  | 중국 좋은 품질 접시형 머리 나사 공급업체. 저작권 © 2025 NINGBO YONGBIAO FASTENER CO.,LTD . 판권 소유.