How we source, score, and update

Our FOB Shanghai prices (6063-T5, 6061-T6, 6005A-T5, ACP 4mm PVDF) are derived weekly composites, not a private mill survey. Each price is built from three public benchmarks plus a typical export-to-spot margin observed in listed-mill annual reports (Xingfa HKEX 0098, Mingtai SH:601677, Nanshan SH:600219, others).

Inputs: LME 3M Aluminium (Yahoo Finance ALI=F snapshot), SHFE main contract (post-close 15:00 CST), and Changjiang A00 spot (ccmn.cn 10:30 CST), normalized to USD/t at PBOC USD/CNY midpoint. The export margin is bracketed at 12-15% (current observation) for architectural alloys, with a separate margin band for ACP given its sheet-and-coating cost structure.

This methodology is intentionally fully reproducible from public sources; the formula is in scripts/scraper/tasks/ and changes are versioned by git history. Earlier copy implied a private "13-mill panel" — that was inaccurate language and was corrected in the 2026-04-22 content audit.

Landed cost = FOB price + ocean freight + insurance + destination port fees + import duty + anti-dumping + VAT + inland trucking. Each line is itemized in the calculator output so you can see what's driving the total.

• FOB — weekly composite from our price benchmarks (see §2 above), or your own input.
• Ocean freight — Freightos Baltic Index (FBX) origin→destination route, refreshed daily.
• Insurance — 0.3% of CIF default (institutional buyer rate); user-overridable.
• Duty — destination MFN rate from our tariffs table (HS chapter 76 lines), refreshed monthly from official tariff schedules.
• Anti-dumping (US/EU/CA) — order-specific ceiling rates from access.trade.gov / EUR-Lex; per-exporter rates may differ.
• VAT / GST — destination country rate applied on the duty-paid CIF base.
• Port fees + trucking — destination-specific defaults from forwarder quotes (Q1 2026 sample); user-overridable.

All currency conversions use PBOC / central-bank midpoints (see §1 sources). The calculator is a planning tool — actual landed cost depends on your forwarder, broker, and the specific HS line. Always confirm with a licensed customs broker before committing to a shipment.

TrustScore = clamp(
  SAMR_base (10 points if active registration)
  + customs_volume_score (0-30; ln-scaled against peer median)
  + certifications_depth (0-15; ISO9001=3, ISO14001=3, Qualicoat=3, IATF=3, GB/T 5237=3)
  + export_share (0-15; linear 0-100%)
  + market_fit (0-15; weighted by matches to requested buyer market)
  + listed_bonus (+5 if public-listed)
  - risk_flags (-25 max; UFLPA-adjacent, trademark-counterfeiting, AD evasion)
  - stale_filing_penalty (-5 if no customs filing in 90 days),
  0, 100
)

Tier A = 80-100 · Tier B = 60-79 · Tier C = <60. Tier labels shown on supplier cards and ranking tables. Raw per-mill component breakdown is downloadable from each supplier's profile page once the Supabase layer is live.

Each ranking publishes its own abridged methodology in the body of the ranking page. In general: flagship rankings (annual) use a broader 6-factor weighting; market-specific rankings use destination-market-weighted customs volume as the primary signal.

No fraud case is published without at least two of:

1. Public dispute filing (court, arbitration, customs) or press coverage.
2. Submitted MTC, SGS, or spectro evidence from the affected buyer.
3. Customs record corroboration (volume drop, HS code mismatch).

The named seller is contacted for comment before publishing where possible. Their response (or refusal) is appended to the case record.

We fix errors. Publicly. With a note.

• Factual corrections (price, capacity, registration status) are published inline on the affected page with a visible note and the date we fixed it. An archived corrections index is planned for Phase 2.
• Editorial corrections (mischaracterization, unclear attribution) trigger an update to the article with a visible correction note at top.
• Take-down requests for defamation or false-fact claims are evaluated within 48 hours.