Our three trial calculators — Colorado Trial, Colorado Domestic, and Colorado 16.1 Simplified Calculator — literally put the outline of your deadlines at your fingertips.

Our circular calculators are precise — they're printed by a company that specializes in the production of aeronautical and navigational instruments — and guaranteed to a tolerance of .005". And they're durable — made of hard plastic for years of use.

The Colorado Trial Calculator®, our most popular offering, is also available as PC-compatible software.