What size steel do I need for this knife?

How the numbers are worked out

Bar width is your blade height at the ricasso plus 1/8 in of clean-up, rounded up to the next standard width. Master Smith Steven Culver describes using the same rule. Thickness is your finished spine, rounded up to the next standard bar thickness.

Forged blades are worked out by conservation of volume, not by a draw ratio. The finished blade and tang are measured as cross-section × length, divided by the bar's own cross-section less the scale the steel loses in the fire. That loss depends mostly on your forge, how hot you run it and how many heats you take, but alloy plays a part, so each steel has its own default (4.5% for 80CrV2, 5.5% for 1095, for example). They are starting estimates, not measured values. The draw ratio comes out the far end as a result you can sanity-check, rather than going in as a guess.

Stock removal needs a piece long enough for blade plus tang, plus the clean-up you cut off the ends. Everything outside the profile becomes grinding dust.

What is still estimated. Four numbers, and they are flagged as estimates in the results panel every time: the fraction of the blade's bounding box that is steel once the bevels are ground (0.68), the same for the tang (0.90), how much the blade thins from ricasso to tip (distal taper, averaging to about 0.70 of the ricasso thickness by default), and how much extra steel a forged blank loses to grinding and clean-up beyond forge scale, from bevels, straightening, plunge and tang (25%). The first three are reasoned shapes, not measurements; the fourth is one bladesmith's own weighed knife (256 g raw to about 182 g finished, 29% in all, less an assumed 5% for scale) rather than a reasoned guess, but it's still one data point. Treat the forged stock lengths as good starting figures and check your first bar. Everything else above is arithmetic. Unlike a draw ratio, a fill fraction is checkable on a kitchen scale (weigh a finished blade and compare it with "finished blade weight" above), and the two fill fractions plus grinding loss are editable under Calibration if yours come out different. Grinding loss is checked differently, though: weigh your own raw blank against the finished knife, since it only changes how much bar you buy, never the finished weight. Distal taper isn't an editable control yet. The tang's cross-section matters as much as the blade's, which is why the advanced panel asks for tang height and thickness rather than settling for "hidden" or "full".

Sanity check: a student's account of an ABS intro class (ABS forum, Nov 2013) lists a 4 in drop point forged from 1 × 1/4 in, a 7 in blade from 1¼ × 1/4 in, and the 10 in test knife from 1½ × 1/4 in; a Master Smith in the same thread forges most knives from 1/4 in bar with a width about 1/8 in over the ricasso. The calculator lands on the same answers.

Weights and prices use nominal bar size and September 2026 retail prices from knife-steel suppliers. Hot-rolled bar from most suppliers ships oversize (a nominal 1/8 in bar often measures 0.135–0.155 in), so real weight can run 8–24% higher than shown (and cost too, if your supplier sells by weight); precision-ground stock is on size.