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All-In Sustaining Cost (AISC)

Updated Jun 24, 2026 at 8:22pm

Research Draft High 1,217 words

All-In Sustaining Cost (AISC) is a non-GAAP per-ounce (or per-pound) cost metric introduced by the World Gold Council (WGC) in June 2013 to capture the full recurring cost of keeping a mine in business — not just the cost of pulling ore out of the ground. Before AISC, miners headlined "cash cost," which excluded sustaining capital, corporate overhead, and reclamation, and made profitable-looking mines that were actually burning cash. AISC's core tension is that it is genuinely more honest than cash cost, yet because it is non-GAAP and self-defined, the line between "sustaining" and "growth" spending is judgmental — and that line is exactly where managements can flatter the number.

How it's calculated

AISC builds outward from cash cost in layers. The WGC's "Guidance Note on Non-GAAP Metrics" (2013, updated 2018) defines three nested measures:

1. Total cash cost — direct mining, processing, on-site G&A, royalties, and production taxes (roughly the old "C1" plus royalties). 2. AISC = total cash cost + corporate G&A + sustaining capital expenditure + sustaining exploration/study costs + reclamation/remediation accretion and amortization + sustaining leases. 3. All-In Cost (AIC) = AISC + non-sustaining (growth) capital, greenfield exploration, and major-project spend.

Expressed as a formula, the common simplification is:

> AISC ($/oz) ≈ (Total cash costs + Corporate G&A + Sustaining capex + Reclamation) ÷ ounces produced

The pivotal judgment is sustaining vs. non-sustaining. The WGC defines non-sustaining (growth) spend as costs at new operations or major projects at existing operations that deliver a material benefit — defined as at least a 10% increase in annual or life-of-mine production, NPV, or reserves (per the WGC Guidance Note). Anything below that threshold is "sustaining" and flows into AISC.

By-product credits matter for polymetallic mines. Most producers net by-product revenue (e.g., silver or copper sold by a primary gold mine) against cost, producing a lower AISC; this can occasionally drive a reported AISC near or below zero when by-product revenue exceeds total cost (per Montana Tech analysis, in Comparison of All-in Sustaining Costs). The alternative co-product method allocates cost across metals instead. The two methods are not comparable, and the choice is the company's.

How it's used in practice

AISC is the single most-watched operating number for precious-metals (and increasingly silver) producers. Its main uses:

  • Margin gauge. AISC margin = realized metal price − AISC. With the GDX top-25 miners' average AISC around $1,424/oz in Q2 2025 (up ~10.5% year-over-year, per Mining.com's quarterly fundamentals series) against a quarterly average gold price near $3,285/oz (same source), miners ran unusually wide margins in 2025.
  • Cost-curve positioning. Analysts rank mines on a global AISC cost curve (maintained by the WGC via Metals Focus' Gold Mine Cost Service). Low-quartile mines survive price downturns; high-quartile mines are first to be put on care-and-maintenance.
  • Downside / break-even analysis. AISC approximates the metal price below which a mine bleeds cash on a sustaining basis — a key input for stress-testing a producer at lower gold prices.
  • Cross-company and cross-mine comparison — its original purpose, allowing investors to compare a South African deep mine against an Australian open pit on a common (if imperfect) basis.

Adoption, debate & evidence

AISC achieved near-universal adoption among gold and silver producers within a couple of years of the 2013 guidance — it is now the de facto industry standard and is quoted in essentially every senior and mid-tier producer's quarterly release. That adoption is the metric's biggest strength and the root of its biggest weakness.

The contested point is comparability, which the WGC explicitly aimed to deliver but only partly achieves:

  • Inconsistent application. Academic review (Montana Tech, All-in Sustaining Cost Analysis) found leading producers applied the guidance differently — some historically disclosed only AISC while others disclosed both AISC and AIC, and the sustaining/non-sustaining split varied.
  • Accounting-standard differences. Under US GAAP, open-pit stripping costs in the production phase are expensed to inventory and generally cannot be capitalized (EITF 04-6, now codified as ASC 930-330), whereas IFRS (IFRIC 20) permits capitalizing qualifying production-phase stripping as a non-current asset. The same mine therefore reports a different AISC depending on its reporting regime — a structural, not behavioral, distortion.
  • No regulator enforces it. AISC is non-GAAP and voluntary; the SEC requires reconciliation to GAAP measures but does not police the AISC definition itself.
  • Regional reality check. WGC AISC data shows wide regional spreads (e.g., South America ~$1,197/oz vs. Africa ~$1,532/oz in Q3 2024), and costs have trended persistently upward — the WGC's own commentary notes AISC moving "ever upwards." Country/grade mix, not just management skill, drives much of the difference.

So the evidence: AISC is a real improvement over cash cost and broadly reliable for trend and cost-curve analysis, but precise inter-company comparisons should be treated as indicative, not exact.

Strengths & limitations

Strengths. Far more complete than cash cost; captures the capital a mine must keep spending just to stand still; widely reported, so peer comparison is at least possible; an intuitive margin and break-even tool.

Limitations / the #1 misuse. The single most common error is treating AISC as the true all-in break-even. It deliberately excludes growth capex, financing/interest, taxes, and (under most definitions) working-capital and depletion of the reserve base. A miner can show a low AISC while spending heavily on growth projects (captured only in AIC) and still be free-cash-flow negative. Other traps: AISC is a per-ounce average that hides quarter-to-quarter volatility (it falls in high-grade quarters and spikes when grades dip or capex lumps in); by-product netting can make a polymetallic miner's AISC misleadingly low or even negative; and the 10% materiality line gives management latitude to push spend out of AISC into "growth." Always read AISC alongside AIC, free cash flow, and grade trends.

Sources

Dispute flagged: there is no enforced, regulator-policed AISC standard; cross-company AISC comparisons are indicative, and the sustaining/non-sustaining split is a known soft spot open to management discretion.