Skip to main content

Bulb Calculator

Wondering how many bulbs to buy to fill a certain area? Use these bulb calculations.

Wondering how many bulbs to buy to fill a certain area? Use these bulb calculations.


The tag that comes with your bulbs should indicate their proper spacing. Proper spacing will keep the bulbs from competing with each other for water and nutrients, promoting better bloom in subsequent years. In general, large bulbs such as most tulips, hyacinths and daffodils should be spaced 6 inches apart, or 5 bulbs per square foot. Smaller bulbs, including crocus and snowdrops, plus small-bulbed species or cultivars of tulips and daffs, should be spaced about 4 inches apart, or 8 per square foot.

To determine the number of bulbs you need to fill a certain space, multiply its length by its width, in feet, to find the area. Then multiply the area by the recommended number of bulbs per square foot to determine how many bulbs you need in total.

For example, say you are planting a 4-foot by 8-foot rectangle with large tulips. Multiply 4 by 8 to get the total area: 32 square feet. It's recommended that 5 large tulips are planted per square foot. Multiplying 32 square feet by 5 tulips gives you 160 tulip bulbs needed in total.

For more help in calculating area—including for circular, triangular or irregularly shapes—and more bulb-per-square-foot recommendations, see the Bed Area Calculations page of

Learn everything you need to know about bulbs with Bulbs: Practical Advice and the Science Behind It.

Join Chris Weisinger on his bulb-hunting adventures through the Southern US. His book,Heirloom Bulbs, recounts his travels and offers advice on choosing, planting and tending bulbs, especially in the South.

Planting tons of bulbs? Get it done quickly and painlessly with Clarington Forge's Bulb Planter.