National Metric Day

Celebrated on 10/10/2026

Quick Fact

National Metric Day is celebrated on October 10th, a date chosen because it can be written as 10/10, representing the base-10 system of the metric system. The holiday promotes the use of the International System of Units (SI), which is used by all countries except the United States, Liberia, and Myanmar.

Origins and Establishment of National Metric Day

National Metric Day was established in 1975 by the U.S. Metric Board following the passage of the Metric Conversion Act of 1975. The act declared a national policy to increase the voluntary use of the metric system in the United States. The date, October 10th, was chosen to symbolically represent the base-10 nature of the metric system (10/10). The holiday was intended to raise public awareness and encourage adoption of metric units in everyday life.

Evolution and Modern Commemoration

Over time, National Metric Day has evolved from a government-led campaign into a grassroots educational event. While the U.S. Metric Board was dissolved in 1982, the holiday continues to be observed by educators, scientists, and metric enthusiasts. Celebrations often include classroom activities, quizzes, and community events that highlight the simplicity and global prevalence of the metric system. Today, it serves as a reminder of the benefits of a unified measurement system, especially in science, medicine, and international trade.

Facts & General Observations

• The United States is one of only three countries that have not officially adopted the metric system, alongside Liberia and Myanmar.
• The metric system is used in science and medicine worldwide, including in the U.S., where it is the standard for research and pharmaceuticals.
• National Metric Day is part of National Metric Week, which includes the week containing October 10th.

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