Quilt Size Calculator
Calculate quilt dimensions, block count, and fabric yardage from bed size. Enter values for instant results with step-by-step formulas.
Reviewed for accuracy by Daniel Agrici, Founder & Lead Developer
Quilt Size Calculator
Calculator
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Formula: Quilt Size = Mattress + (2 * Side Drop) x (Mattress Length + Foot Drop + Pillow Tuck)
Worked example — 42 blocks (6x7 layout) | Finished quilt: ~90 x 105 in | Total fabric: ~16 yards
Formula
Quilt Size = Mattress + (2 * Side Drop) x (Mattress Length + Foot Drop + Pillow Tuck)
The quilt width equals the mattress width plus twice the side drop. The quilt length equals the mattress length plus the foot drop and pillow tuck. Blocks are calculated by dividing the inner dimensions (after subtracting borders) by the effective block size (block plus sashing).
Worked Examples
Example 1: Queen Bed Quilt with 12-inch Blocks
Problem:Calculate blocks and fabric for a Queen quilt (60x80 mattress) with 15-inch side drop, 15-inch foot drop, 10-inch pillow tuck, 12-inch blocks, 2-inch sashing, 4-inch border.
Solution:Quilt size: (60 + 30) x (80 + 15 + 10) = 90 x 105 inches Inner area: (90 - 8) x (105 - 8) = 82 x 97 inches Effective block: 12 + 2 = 14 inches Blocks across: ceil(82/14) = 6 Blocks down: ceil(97/14) = 7 Total blocks: 6 * 7 = 42 Block fabric: ~3.50 yards Backing: ~8.75 yards (pieced)
Result:42 blocks (6x7 layout) | Finished quilt: ~90 x 105 in | Total fabric: ~16 yards
Example 2: Baby Crib Quilt
Problem:Make a crib quilt (28x52 mattress) with 6-inch drop, no pillow tuck, 9-inch blocks, 1.5-inch sashing, 3-inch border.
Solution:Quilt size: (28 + 12) x (52 + 6 + 0) = 40 x 58 inches Inner area: (40 - 6) x (58 - 6) = 34 x 52 inches Effective block: 9 + 1.5 = 10.5 inches Blocks across: ceil(34/10.5) = 4 Blocks down: ceil(52/10.5) = 5 Total blocks: 20
Result:20 blocks (4x5 layout) | Finished quilt: ~45 x 58 in | Total fabric: ~6 yards
Frequently Asked Questions
How do I determine the right quilt size for my bed?
The right quilt size depends on your mattress dimensions plus the desired drop on each side and at the foot, and any pillow tuck allowance at the top. Start with your mattress size (for example, a Queen is 60 by 80 inches) and add the side drop on both sides (typically 12 to 21 inches per side depending on whether you want the quilt to reach the bed frame, below the box spring, or to the floor). Add the foot drop at the bottom and a pillow tuck of 6 to 12 inches at the top if desired. For a Queen bed with 15-inch side drops, 15-inch foot drop, and 10-inch pillow tuck, the finished quilt would be 90 by 105 inches. Always measure your actual bed since mattress thicknesses vary significantly and affect the drop distance.
How many quilt blocks do I need for my project?
The number of blocks depends on the finished quilt size, individual block size, sashing width, and border width. First subtract the total border width from both the quilt width and length to find the inner area. Then divide each inner dimension by the effective block size (block size plus sashing width) and round up. Multiply the across and down counts for the total. For example, a 90-inch wide quilt with 4-inch borders on each side leaves 82 inches of inner width. With 12-inch blocks and 2-inch sashing, each effective block unit is 14 inches. That requires 6 blocks across (6 times 14 equals 84, close to 82). Most quilters round to make the pattern work, then adjust borders slightly. Quilt Size Calculator handles the math automatically and adjusts the final quilt dimensions to accommodate complete blocks.
How much fabric should I buy for a quilt?
Fabric requirements include several components: block fabric, sashing, borders, backing, and binding. For blocks, calculate the cut size (finished block plus seam allowances on all sides) and determine how many fit across your fabric width. Block fabric typically requires 2 to 5 yards depending on quilt size and block complexity. Sashing generally needs 1 to 3 yards. Border fabric depends on the border width and quilt perimeter, usually 1 to 2 yards. Backing requires the most fabric, typically 5 to 9 yards for a bed quilt because you need to piece panels together when the quilt is wider than the fabric bolt width. Binding fabric for a bed quilt needs about 0.75 to 1 yard. Always buy 10 to 15 percent extra fabric to account for cutting errors, fabric shrinkage, and pattern matching.
What are standard quilt block sizes and which should I choose?
The most common finished block sizes are 6, 9, 10, 12, and 15 inches square. Twelve-inch blocks are the most popular because they divide evenly into many standard quilt sizes and work well with common grid-based patterns like nine-patch, log cabin, and star designs. Nine-inch blocks are great for smaller quilts and intricate piecing patterns. Six-inch blocks create detailed, complex-looking quilts but require more blocks and more sewing time. Fifteen-inch blocks cover area quickly and are excellent for beginner projects or when using large-scale print fabrics. Consider your skill level, available time, and desired visual effect when choosing. Larger blocks are faster to assemble but show less pattern complexity, while smaller blocks create more intricate designs at the cost of additional cutting and piecing work.
What is sashing and how does it affect my quilt design?
Sashing consists of fabric strips sewn between quilt blocks that create visual separation and add structure to the overall design. Sashing width typically ranges from 1.5 to 4 inches, with 2 to 3 inches being most common. Sashing serves several purposes: it frames individual blocks to showcase each one separately, adds to the overall quilt dimensions without requiring additional blocks, can introduce a complementary color or pattern, and can visually unify blocks that might not look cohesive when placed directly next to each other. Cornerstones (small squares at sashing intersections) add another design element. Some quilters also use sashing to correct minor differences in block sizes, as the sashing strips can be adjusted slightly to compensate. When calculating fabric requirements, remember that sashing adds significantly to yardage needs.
References
Background & Theory
Standard Mattress Dimensions Used in This Calculator
Quilt sizing starts from the mattress, not a generic "queen quilt" assumption, because actual mattress dimensions vary by only a few inches between similar-sounding sizes but that difference compounds once side drop and foot drop are added.
| Bed size | Mattress (W x L, inches) | Typical finished quilt (15" drop, 10" tuck) |
|---|---|---|
| Crib | 28 x 52 | 58 x 77 (often made smaller for safety) |
| Twin | 39 x 75 | 69 x 100 |
| Full/Double | 54 x 75 | 84 x 100 |
| Queen | 60 x 80 | 90 x 105 |
| King | 76 x 80 | 106 x 105 |
| California King | 72 x 84 | 102 x 109 |
Mattress dimensions per Quilting Daily's published quilt size chart (see References). Actual mattress thickness varies, which changes how far a given side-drop reaches down the box spring — measure your own bed before finalizing a gift quilt's size.
Real-World Use Case: Fitting a Repeating Block Pattern to an Odd-Size Bed
Block-based quilts rarely divide evenly into a target size — a 90-inch quilt width with 4-inch borders leaves 82 inches of inner space, and 12-inch blocks with 2-inch sashing (14-inch effective units) only fit 5.86 times across. Rather than cutting a partial block, quilters round up to 6 blocks across (84 inches of block-and-sashing) and let the finished quilt run slightly wider than the original target, or adjust the border width to absorb the difference. This calculator solves that rounding automatically and reports the actual achievable quilt size rather than silently returning a size that doesn't correspond to a real block layout.
Reviewed for accuracy by Daniel Agrici, Founder & Lead Developer · Editorial policy
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