Sale has ended but you can still get this app.
Download Field Headland Calculator Now

Official Description

Insert the total area of your field in hectares followed by width in meters of the headland you wish to measure.
This app will then calculate the area of the headland and the remaining area of the field
Fields may vary because of odd shapes but this app is a useful guide when calculating seed,fertilizer,& Sprays requirements
You can also e-mail the answer
Available in German & Polish