Enter the blade you're planning and get the bar to buy, how many blades a bar yields, and what the steel costs per blade. Works for forged and stock-removal knives.
Stock removal: the bar is cut to blade + tang + clean-up, so the tang section and forged thickness below only change the finished-weight estimate. Switch to Forged and they change the stock length too.
Tang dimensions are estimated from the tang style until you change them. Measuring yours is worth doing — a forged blank's length depends on the tang's cross-section, not on what the tang is called.
Stock removal: fill factors only change the finished-weight estimate here. They set the stock length when the method is Forged. Grinding loss has no effect at all in stock removal — the bar is cut straight to the profile, nothing is drawn out.
The fraction of the blade's and tang's bounding box that is actually steel once the bevels are ground. Distal taper is factored in separately now (see "Distal taper" below, under What this assumed) and isn't editable here yet — these two fill factors are the ones worth replacing with your own measurements: weigh a finished blade, then adjust until the finished weight below matches the scale.
Steel is only part of the cost. Add abrasives, handle, heat treat and your time, and see the price that actually pays you.
Copy link to this calculationBar sizes for ten common knife patterns, weight per inch for every standard flat bar, and quick heat-treat numbers for the usual carbon steels. Print it, tape it to the grinder.
Bar width is your blade height at the ricasso plus 1/8 in of clean-up, rounded up to the next standard width — the same rule most experienced smiths use. 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 — which is a property of the alloy, so 80CrV2 at 4.5% and 1095 at 5.5% give different answers from the same bar. 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 each end. 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 0.72 of the ricasso thickness by default), and how much extra steel a forged blank loses to grinding and clean-up beyond forge scale — bevels, straightening, plunge, tang (25%). The first three are reasoned shapes, not measurements; the fourth is one bladesmith's own weighed knife (256 g raw to ~182 g finished) 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 and cost can run 8–18% higher than shown; precision-ground stock is on size.