You will participate in the farming activities of your hosts in a free and voluntary manner. The participation WWOOFers offer is commonly the equivalent of five half days per week, although the exact schedule is agreed prior to final commitment, to suit both sides. It can vary slightly from country to country; in most countries it is around 25 hours per week. For further information, please check the terms and conditions of the national WWOOF organization you are interested in joining or are a member of.
The host-WWOOFer agreement is in no way a binding contract. It is best to tailor each agreement with each host on a day-by-day or a week-by-week basis.