The WeZero GHG calculator measures Scope 1, 2 and 3 emissions using UK Government (DESNZ) conversion factors. Fuel, fleet, electricity, process and Scope 3 data are entered in separate tabs, with support for litres, kWh and cubic metres, net and gross calorific values, fuel blends and bioenergy. Grey fleet mileage is converted automatically using published factors, and vehicles can be entered by registration year with official g/km figures. Every result shows the calculation steps and the factor used, so figures can be traced back to source. One submission is stored per reporting year, and past years can be reopened and edited. The calculator is free; paid plans add SECR reporting, master dashboards and exports.