The answer to this question depends on the audience for the plan and the type of business. If the plan is going to be used to search for financing from a lender, then the plan may be required to be comprehensive and detailed, and the primary emphasis should be on the financial statements. If the plan is for internal use, then you might spend more time on the mission and purpose of the business.
More important than length is what the plan says. Some long plans may communicate very little, while some very short plans concisely communicate the essence of the venture. Thoughtfully and thoroughly considering all the areas of the plan is much more important than attempting to reach a certain length. Also, you should be prepared to revisit the business plan periodically and make revisions and updates as your business grows and changes. The best business plans are the ones that get used.
