A typical full-size orchestral tuba weighs 25 to 35 pounds. The player does not need to hold up the heavy instrument without assistance. The chair the musician sits in supports the tuba's weight.
In part, the weight of a tuba depends upon its size. The most common options for tubas are 3/4, 4/4, 5/4 and 6/4 sizes. The variations between the lengths depends upon manufacturer. While there is consistency in size within one company, tuba sizes are not the same across different companies.
When tuba players are unable to perform while sitting, such as in marching bands, their instruments often weigh significantly less. Some drum corps tubas weigh only 15 pounds.