A technique to compute vehicle weight (GVW or GCW) solely from measurements of force and acceleration taken onboard the tractor is described. A means to measure both variables by a single inexpensive sensor is disclosed, and algorithms are presented. Methods to compensate for real-world variables such as wind and grade are discussed, as are results obtained during 20,000 Km of testing. A potential means to determine GCW onboard the tractor without any additional hardware is presented. Applications, including ITS, are discussed, as are methods for instantaneous calibration.