In millimeters, how many millimeters are there in 1 inch?

One inch is precisely equivalent to 25.4 millimeters. This conversion is important in various fields, such as construction and engineering, where measurements can be required in different units. Knowing that one inch equals 25.4 millimeters is essential for accuracy when using tools and preparing materials, particularly in building projects where specifications must be followed closely.

While it may seem reasonable to round this figure to 25 mm for simplicity in informal contexts, precision is crucial in professional settings, and the accurate value is exactly 25.4 mm. This ensures that any calculations involving inches and millimeters maintain the integrity expected in construction and other technical disciplines.