Net sales for the quarter increased by US$ 100.2 million or 43.4% to US$ 330.8 million compared to US$ 230.6 million in the same period in 2018. Total billings increased by US$ 67.1 million or 28.3% to US$ 304.5 million for the three months ended June 30, 2019 compared to US$ 237.4 million in the same period in 2018. Net sales of wind blades were US$ 301.8 million for the quarter as compared to US$ 206.4 million in the same period in 2018.
The increase was primarily driven by a 23% increase in the number of wind blades produced and a higher average sales price due to the mix of wind blade models produced year over year. Total cost of goods sold for the quarter was US$ 308.2 million and included US$ 14.7 million related to 13 lines in startup in our plants in Mexico and China and the startup of new wind blade models for a customer in Turkey and US$ 8.2 million related to the seven lines in transition during the quarter. This compares to total cost of goods sold of US$ 215.6 million for the same period in 2018. Net income for the quarter was US$ 1.8 million as compared to a net loss of US$ 4.1 million in the same period in 2018. EBITDA for the quarter increased to US$ 11.7 million, compared to US$ 10.1 million during the same period in 2018. Adjusted EBITDA for the quarter increased to US$ 19.5 million compared to US$ 13.5 million during the same period in 2018. Adjusted EBITDA margin increased slightly to 5.9% compared to 5.8% during the same period in 2018.
