Research shows that smaller field size favours biodiversity and it is hypothesized that autonomous arable crop equipment would make it possible to farm small fields profitably. To test this hypothesis algorithms were developed for machine time over a range of field sizes. The Hands Free Hectare (HFH) linear programming model was used to assess the economic implications of field sizes. The study considered rectangular fields in the West Midlands from 1 to 100 ha farmed with tractor sizes of 38 hp, 150 hp and 296 hp. Results showed that field times (hours/hectare) were longer for small fields with equipment of all sizes and types, but field size had the least impact for small equipment. The results showed that autonomous equipment reduces costs on farms with fields of all sizes. If temporary labour is available, conventional farms with small fields use the smaller equipment, but the extra hiring increases wheat production costs by £30-£40/ton over costs on farms with autonomous equipment. The larger 150 hp and 296 hp tractors were not profitable on the farms with small fields. The economic viability of autonomous equipment irrespective of field sizes shows that it could facilitate biodiversity gains and environment schemes, such as Environmental land management schemes (ELMS) in the United Kingdom and Agri-environment schemes (AES) in the European Union and elsewhere.