Chicken eggshell contains about 380 mg of calcium per gram of shell, roughly 40% calcium by weight — half a shell can cover half of an adult’s daily.

As of 2025, a large whole egg contains about 25 to 28 milligrams of calcium, nearly all of it in the yolk..

A whole medium avocado contains about 18–20 mg of calcium, but a standard serving (one-third to one-half of the fruit) delivers between 6 and 17 mg.

A medium-sized apple (about 182 grams) contains approximately 10.9 mg of calcium, which is less than 1% of the daily recommended intake for most.

One ounce of almonds (about 23 nuts) provides roughly 75 to 80 milligrams of calcium, which is about 6 to 8% of the Daily Value.

A medium sweet potato contains roughly 40 to 90 mg of calcium depending on size and variety.

A standard 1-ounce slice of hard cheese like cheddar provides about 200 mg of calcium, roughly 15% of the Daily Value.

A gallon of milk contains approximately 4,800 mg of calcium, based on the standard 300 mg per cup across 16 servings.

A standard 8-ounce cup of whole milk provides roughly 300 milligrams of calcium, meeting about 25% of the daily value for most adults.

A cup of raw spinach has about 30 mg of calcium, and a cooked cup has roughly 245 mg, though oxalates limit absorption to an estimated 5%.