Fiber Reinforcement Calculator

No -- Total Fiber (lbs) is simply Concrete Volume times Dosage (lbs/yd³); the formula never references Fiber Type. Fiber Type does change several other outputs at the same total weight, though: bag size and price per pound (so Bags Needed and Estimated Cost swing widely), Volume Fraction (%) (steel fiber's much higher density means the same pounds occupy roughly 1/8.6 the volume percentage that synthetic fiber does), and Dosage Adequate, since each fiber type is checked against its own typical minimum rate -- the same 1.5 lb/yd³ dosage that's adequate for synthetic micro fiber reads inadequate for steel or macro.

Dosage Adequate checks your entered dosage against each fiber type's own typical minimum (80% of its typical rate). A 1.5 lb/yd³ dosage clears that bar for synthetic micro fiber (typical about 1.5 lb/yd³) but falls far short of steel fiber's typical about 50 lb/yd³ or macro fiber's about 5 lb/yd³, since structural fibers need much higher loading rates.

No -- Volume Fraction (%) is the ratio of dosage to fiber density, and Concrete Volume cancels out of that ratio algebraically. Doubling the pour size doubles Total Fiber (lbs) proportionally, but the percentage of fiber by volume in the mix stays exactly the same.

At the default 10 yd³ pour and 1.5 lb/yd³ dosage, Steel Fiber is cheapest per pound at $1.25/lb even though it ships in large 50 lb bags, while Synthetic Macro is the most expensive at $4.00/lb. Steel fiber typically needs a much higher dosage for structural use, though, so true cost per cubic yard depends heavily on the dosage your engineer specifies.