Do all Spanish-speaking countries use the metric system?

That's right, the three countries which are not using the metric system are Liberia, Myanmar and of course… the United States of America. ... made it “lawful throughout the United States of America to employ the weights and measures of the metric system in all contracts, dealings or court proceedings. read more

Countries use the metric system because it is a sensible, easy to use and consistent system of measurements. All the individual units can be readily used in combination with each other, without the need for any numerical conversion factors. read more

There are only three countries in the world that do not use the metric system for official measurement. The United States, Burma (Myanmar) and Liberia all depend on older systems of measurements. Within these countries, however, the metric system is often used, especially in scientific and international contexts. read more