The strict definition of wood moisture content is the weight of water in a piece of wood compared to these pieces oven-dry weight. Moisture content is always expressed in percent (%), so we multiply the answer by 100.
We measure the amount of water by weighing the piece of wood, then oven-drying the piece at 215 degrees Fahrenheit for 12 to 36 hours, until the wood is dry. And then, reweighing the piece after oven-drying.
The difference between the two weights is the amount of water that was in the wood before drying. The final weight is the oven-dry weight.