Fabric Yardage Calculator

Fabric Needed, With Safety Margin, and Meters Needed are computed entirely from Garment Type, Garment Size, Fabric Width, and Pattern Repeat (lines 15-46) -- Price per Yard is never part of that calculation. It is applied one step later, multiplying the already-finalized yardage to produce Fabric Cost and Cost with Extra (lines 48-50), so it can change your total spend without ever changing the yardage figures themselves.

The base yardage figure from the garment/size lookup table assumes standard 45-inch fabric. Fabric Width applies a discount on top of that base: 15% less yardage at 54 up to 59 inches wide, and 25% less at 60 inches or wider, because a wider bolt covers the same pattern pieces with less linear length (lines 28-32).

With Safety Margin adds a flat 0.25 yards to the already-rounded Fabric Needed figure and then rounds that sum up to the nearest eighth of a yard on its own (line 49). If Fabric Needed already sits at a clean eighth-yard value the difference works out to exactly a quarter yard, but if it does not, the second rounding step can push the actual gap slightly above or below 0.25 yards.

Setting Pattern Repeat above 0 first adds a proportional waste allowance based on how much of a yard each repeat consumes, then takes the resulting yardage in inches and rounds it up to the next whole multiple of the pattern repeat length itself, before the calculator's usual round-up to the nearest eighth-yard (lines 35-42). This two-stage rounding means large repeat lengths can push required yardage up by more than the waste allowance alone would suggest.