Methodology

The formula

For each offer we estimate:

landed total = item price + shipping + import duty/tax + import/carrier handling + payment/currency-conversion fee

Every component is stored in integer minor units and converted once at the exchange-rate snapshot shown on the page. Each component is labeled Confirmed, Estimated, Unknown, or not applicable. Unknown components are never treated as zero: a result with an unknown component is Partial and is not ranked as definitively cheaper than a complete result.

Amounts are rounded to the nearest US cent using round-half-up. Rounding is applied to each component at conversion time so the breakdown adds up to the displayed total.

Statuses

• Confirmed — sourced for this exact offer and still within its freshness window.
• Estimated — calculated from a documented shipping, duty, handling, or fee assumption.
• Partial — one or more components are unknown; not a definitive cheapest result.
• Unavailable — cannot currently be ordered for the selected destination.

Confidence

We do not use a pseudo-precise percentage. Confidence is a categorical label:

• High — all required components confirmed and fresh.
• Medium — a complete total with at least one documented estimate.
• Low — a required component is unknown, data is stale, or destination applicability is uncertain.

Freshness

Each value carries a checked-at timestamp. We derive a conservative offer timestamp from the oldest relevant component. The freshness window is configuration, not hard-coded copy: preorders (30 days) and in-stock items (7 days) age at different rates. When data exceeds its window the result is flagged as possibly outdated.

Ranking

Default order is the lowest estimated landed cost among comparable offers: complete confirmed/estimated totals ascending, then partial totals clearly separated, then unavailable offers. Ties are broken by fresher data, then retailer name. Affiliate status, sponsorship, or retailer preference never affect ranking.

Assumptions and limitations

These are estimates, not quotes. The final retailer, carrier, and customs charges control.

• Payment/currency fees are user assumptions unless the exact method and rate are known; the default is shown and adjustable.
• Preorder shipping that a retailer cannot quote is estimated or unknown, never confirmed.
• We cover the contiguous United States only. Alaska, Hawaii, territories, APO/FPO, and other countries are excluded.
• Exchange rates can move between when data is checked and when you order. We show the snapshot date.
• For legal or tax certainty beyond this scope, seek professional advice.