Canned sardines with bones are an excellent source of calcium. A 3.75-ounce (about 100-gram) serving can provide around 35% of the daily recommended intake of calcium.
Dark leafy greens like collard greens are rich in calcium. One cup of cooked collard greens can contain about 27% of the daily recommended calcium intake.
Many plant-based milk alternatives, such as almond milk, soy milk, and rice milk, are fortified with calcium. A glass of fortified plant-based milk can contain as much or more calcium than cow's milk.
Tofu, made from soybeans, is a good source of calcium. A 4-ounce serving of tofu can provide around 20% of the daily recommended intake of calcium.
Chia seeds are not only a great source of fiber and omega-3 fatty acids but also calcium. Two tablespoons of chia seeds can provide about 18% of the daily recommended intake of calcium.