On average, a 12'12 deck or 144 sq ft. deck should cost between $2,160 to $5,040. That breaks down to an average of about $15 to $30 per square foot. The final cost of your deck can vary depending on materials, size, level built on, and added options. Most contractors provide a free estimate that can help you determine your options and what they cost. Hiring a professional may cost more initially but helps ensure your deck is built properly while eliminating long term problems. However, if you are on a tight budget you can build a DIY deck. If you choose to build your own deck you should do your research beforehand and consult a professional with questions along the way. Building a deck can involve many tools which can be costly if you do not already have them. On average labor for building a deck costs between $8 to $22 per square foot.