تحويل ملليمتر مربع إلى بوصة مربعة: الهندسة والتصنيع والقياس الدقيق

Exactly 645.16 square millimeters equal one square inch. This precise relationship comes from the international definition of the inch as 25.4 millimeters. When you square this linear conversion (25.4 × 25.4), you get 645.16. For quick mental math, remember that 1 in² ≈ 645 mm², but for engineering work, use the full precision of 645.16 to avoid accumulating errors in critical calculations.

Historical standardization and legacy equipment are the primary reasons. North American industries, particularly aerospace and automotive, established their standards using imperial measurements decades ago. Converting entire manufacturing processes to metric would require recalibrating equipment, rewriting specifications, and retraining workforces - a costly process. Many companies now use both systems in parallel, with dual-dimensioned drawings, to accommodate international suppliers and regulatory requirements from different countries.