1. Cost of a deck per square foot Deck size Average cost range 12'x12' (144 square feet) $4,500 � $9,000 10'x12' (120 square feet) $3,700 � $7,400 10'x10' (100 square feet) $3,000 � $6,000 8'x10' (80 square feet) $2,500 � $5,000 6 more rows Deck building cost - Average prices + Saving tips [2024 Data] getasiteplan.com https://getasiteplan.com � deck-building-cost getasiteplan.com https://getasiteplan.com � deck-building-cost 1. Cost of a deck per square foot Deck size Average cost range 12'x12' (144 square feet) $4,500 � $9,000 10'x12' (120 square feet) $3,700 � $7,400 10'x10' (100 square feet) $3,000 � $6,000 8'x10' (80 square feet) $2,500 � $5,000 6 more rows