Tool steel is where a quote that looked routine quietly turns into a loss. The geometry might be simple — a die plate, a punch, a forming insert — but the material fights the cutter, eats tooling, and almost always rides through the furnace mid-job, so the price has to carry a machining penalty, a tooling penalty, and a second operation after hardening. Estimating tool steel machining cost the way you would price a mild-steel bracket underquotes nearly every job, because the same nominal cycle time does far less material removal per hour and burns through inserts doing it.

This guide breaks the cost of cutting D2, A2, O1 and H13 into the parts you can actually estimate — material premium, machinability versus a mild-steel baseline, the annealed-machine-then-harden sequence, the grinding stock you leave behind, and the tooling spend that hides inside cycle time — so you can quote a die or mould job you can defend.

Why tool steel does not price like structural steel

Three things make tool steel behave unlike the mild and structural steels most shops cut every day, and each one moves the quote independently.

• Material cost — tool steel is bought as ground flat stock or precision bar in alloy grades, not commodity bar. Per kilogram it runs several times the price of 1018 or S235, before a single chip is cut.
• Machinability — high alloy content and hard carbides drop the allowable cutting speed sharply. The spindle turns at the same rate per hour; it just removes less metal and wears the edge faster.
• The heat-treat sequence — most tool steel parts are machined soft (annealed), hardened in a furnace, then ground or EDM'd to final size. That second operation after hardening is a cost block estimators routinely forget.

Treat all three as one blended "steel" rate and you misprice the material, undercut the cycle time, and miss the grind entirely.

The four grades a tool-and-die shop actually sees

Most tool steel work in a small-to-mid shop is one of a handful of grades. Here is how they line up on the items that drive a quote. Treat the multipliers as typical bands, not fixed truths — they move with stock form, supplier, and quantity.

Grade	Type	Typical use	Material cost vs mild steel	Machinability (annealed)	Quoting note
O1	Oil-hardening	Low-volume dies, gauges, jigs	~4–6x	Good	Easiest tool steel to cut; minimal distortion on quench.
A2	Air-hardening	Forming dies, punches, blanking	~5–8x	Moderate	Stable in heat treat; tougher on tools than O1.
D2	High-carbon high-chromium	Long-run blanking and stamping dies	~6–10x	Hard	Abrasive carbides wear edges fast; often EDM'd hard.
H13	Hot-work chromium	Die-casting dies, extrusion, forging	~6–9x	Moderate	Gummy and work-hardening; needs sharp tools and coolant.

The relationship matters more than the exact figure. D2 costs roughly twice the material of O1 and cuts at a fraction of the speed, so a punch quoted in D2 at your O1 numbers loses money on both the invoice and the spindle.

Machinability: the rate is the same, the metal removal is not

The single biggest quoting error on tool steel is using a mild-steel cycle time. A part that would run in twenty minutes in 1018 can take forty-five in annealed D2 — same machine, same hourly rate, far less metal removed per hour because the cutting speed has to drop to survive the abrasive carbides.

A rough way to anchor cycle time against a mild-steel baseline of 1.0x on the cutting side:

1. O1, annealed — close to free-machining steel; the friendliest tool steel. ~1.2–1.4x.
2. A2, annealed — tougher, more edge pressure, slower feeds. ~1.4–1.8x.
3. H13, annealed — gummy and work-hardening; sharp coated tools and flood coolant or it galls. ~1.5–2.0x.
4. D2, annealed — high-chromium carbides are abrasive; speeds drop and edges wear. ~1.8–2.5x plus heavier tool spend.

These are starting heuristics, not your shop's numbers. Build the real multipliers from your own time studies the same way you build a machine shop hourly rate — measured, per material family — and the estimate stops being a guess. The principle is the one that governs all difficult materials: the hourly rate holds, but a tougher alloy removes less metal per hour, so cycle time and price both climb.

Tooling: the cost hiding inside cycle time

On mild steel, insert wear is a rounding error. On D2 and H13 it is a real line, and it hides inside cycle time where most estimators never see it. Abrasive chromium carbides in D2 grind the cutting edge down; H13's tendency to work-harden punishes any tool that dwells or rubs. The result is more frequent index changes, more inserts per part, and more spindle-stopped time swapping them.

Two ways to handle it, and either works as long as you do one:

• Roll a tooling allowance into the per-hour rate you apply to tool steel — a higher burdened rate that reflects faster consumable wear.
• Add a separate consumables line for the abrasive grades, estimated from inserts-per-part times insert cost.

What does not work is using your mild-steel tooling assumption on D2. The edges do not last, and the unrecovered insert cost comes straight out of margin.

The sequence that defines the quote: machine soft, harden, then grind

Here is the workflow detail that catches estimators coming from a straight-machining mindset. Most tool steel parts are not cut to final size in one go. The sequence is:

1. Rough and semi-finish in the annealed (soft) state, leaving grinding stock — typically 0.2–0.5 mm per surface on dimensions that must hold tight after hardening.
2. Heat treat — harden and temper to the spec hardness (often 56–62 HRC), which the part comes back from distorted and scaled.
3. Finish to size after hardening — by surface or jig grinding, or by EDM for features a grinder cannot reach.

That third step is its own cost block, and it is the one a flat machining quote misses. Grinding hardened tool steel is slow and skilled; EDM is slower still and runs on its own machine rate. A D2 blanking die quoted only for the soft-state milling is missing the operation that actually holds the tolerance — and that operation can rival the milling in hours. Plan it as a step in the work plan for multi-step operations rather than discovering it after the parts come back hard.

A worked example shows how the blocks stack. Take a small A2 forming punch, batch of one:

Cost block	Estimate	Notes
Material (ground flat stock)	€60	Tool steel premium over mild bar
Soft-state milling	€180	2.5 h at €72/h, A2 cycle penalty
Tooling/consumables	€15	Higher insert wear than mild steel
Heat treat (lot minimum)	€90	Furnace minimum dominates at qty 1
Jig grinding after harden	€130	Holds the post-harden tolerance
Overhead + margin	applied on the total	Per your target margin

Drop the grinding line and you have quoted roughly €345 of work for a part that costs you €475 to make — before margin.

Tolerance, hardness and EDM stack on top

Tool steel parts usually exist because something needs to be hard and precise. That means tight tolerances and demanding finishes ride on top of the machining penalty, not instead of it. A ±0.005 mm die clearance held after hardening forces the grind-or-EDM finish; a sharp internal corner a cutter cannot reach forces sinker or wire EDM. Both are real machine time on machines with their own rates. The tolerance-to-cost logic is the same as for any precision part — see the G&DT tolerances guide for estimators — and on hardened tool steel the tight callouts are less optional than usual, because the part is hard precisely so it can hold them in service.

Stock form and waste also shift the answer. Tool steel bought as ground flat stock is priced for the convenience; machining a die plate from oversize blank leaves clamping and scale allowance on a material that already costs several times mild steel. A twenty percent waste figure that is a rounding error on S235 is a real number on D2.

Read the grade off the drawing — and price it

None of this helps if the grade never makes it from the title block into the estimate. The failure is mundane: the drawing says D2 at 60 HRC, the estimator is busy, "steel die plate" goes into the quote at the mild-steel rate, and the job starts underwater. The same oversight swallows the grinding-stock note and the hardness callout that forces the second operation.

A disciplined quote pulls five things off every tool steel drawing before pricing:

1. The exact grade and condition — O1, A2, D2 or H13, not just "tool steel".
2. The material cost for that grade in the stock form the part needs, waste included.
3. The machining multiplier for that grade against your mild-steel baseline.
4. The hardness and post-harden tolerance, which decide whether a grind or EDM operation is required.
5. Any certification or test-coupon requirement the spec calls out.

Get these right and a D2 die prices well above the same geometry in mild steel — which is exactly correct, because it cost you more to buy, more to cut, and a whole operation more to finish. For the full cost build around these inputs, the cost of CNC machining frames material alongside setup, machine time and margin, and the margin-vs-markup math turns the total into a price.

From drawing to grade-aware price, automatically

The bottleneck is rarely the arithmetic — it is the reading. Catching "D2 / 60 HRC" instead of "steel", remembering the part needs grinding stock left on, applying the right material premium under deadline pressure: that is the part that gets cut when the quote is due by five.

QuoteBuddy reads the technical drawing and surfaces the material callout — grade, hardness, and the features that drive cost — so the estimator works from what the drawing actually specifies rather than a hurried "steel". The cost engine then applies your material prices and per-material machining rates the same way every time, and the multi-step structure lets you carry the soft-state machining, the heat treat, and the post-harden grind as the distinct operations they are.

Start a 30-day trial and run a few of your real tool steel drawings through it — mix in some O1, some A2, a D2 die — and see whether the grade-aware price it builds matches what you would have quoted with the title block in front of you and an hour to think.