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Methodology & Data Sources

Transparency · Sources · Accuracy

Methodology & Data Sources

Every Packzup tool is built on verifiable data sources. This page documents where every number comes from, how often it’s updated, and what to verify before making consequential decisions.

Our principles

  1. Transparency over polish. We’d rather show you “approximate” than fake precision.
  2. Live data when possible. Exchange rates, time zones, and weather pull from authoritative APIs.
  3. Cross-verification. Critical data has at least 2-3 fallback sources.
  4. Official sources required. Visa rules, airline limits, embassy procedures — verified against official government/airline sources.
  5. Confidence indicators. Every tool surfaces “Live”, “Cached”, or “Approximate” status so you know what you’re looking at.

Data sources by tool

💱 Currency Converter

Primary: currency-api via jsDelivr CDN (342 currencies). Fallback chain: Cloudflare Pages mirror → open.er-api.com (166 currencies) → Frankfurter (ECB-backed, 30 currencies). Static fallback: approximate rates flagged with warning.

Update frequency: 60-min localStorage cache with stale-while-revalidate. Accuracy: Mid-market interbank rate. Banks add 2-4% markup on top.

💰 Trip Cost Calculator

Cost data: Traveler-reported averages across 60+ destinations, aggregated from Lonely Planet, Budget Your Trip, Nomad List, BackpackerIndex, and crowdsourced budgets from /r/travel and /r/backpacking. Currency conversion: Live FX via currency-api.

Update frequency: Cost data reviewed annually; FX every 60 min. Accuracy: Mid-range estimates within ±15%. Peak season adds 20-50% to hotel costs.

🌍 Time Zone Converter

Source: IANA timezone database via your browser’s native Intl.DateTimeFormat API. DST transitions handled automatically.

Update frequency: Real-time, every second. Accuracy: Millisecond precision (limited only by your device clock).

✈️ Flight Distance Calculator

Source: Static database of 200+ major international airports with IATA codes and lat/lon coordinates (verified against OpenFlights + ICAO public records). Calculation: Haversine formula for great-circle distance.

Update frequency: Airport database reviewed quarterly. Accuracy: ±2% vs actual flight path (real flights route around airspace + weather). Flight time: Distance ÷ 835 km/h + 30 min taxi. CO₂: ~100g per passenger per km (commercial jet average).

📜 Visa Requirement Checker

Source: Cross-referenced from US State Dept, UK Gov, IATA Travel Centre, individual country embassy sites, and consular announcements.

Update frequency: Quarterly + after major policy changes. Accuracy: ⚠️ Visa rules change frequently. Always verify with the destination’s official embassy/consulate before booking non-refundable flights.

💵 Tipping Calculator

Source: Cultural research from Condé Nast Traveler, Lonely Planet, TripAdvisor local forums, and embassy etiquette guides. Cross-referenced with native speakers and expat communities.

Update frequency: Annual review. Accuracy: Reflects current cultural norms; individual situations vary.

🧳 Carry-On Size Checker

Source: 70+ airline official baggage policy pages, verified against IATA cabin baggage standards.

Update frequency: Quarterly. Accuracy: Current 2026 limits. Always verify with your airline before flying — limits can change with little notice.

⏱️ Layover Calculator

Source: IATA minimum connection times (MCT) for 60+ major hubs, supplemented by airline policy and frequent-flyer community reports.

Update frequency: Quarterly. Accuracy: Industry-standard MCT — we apply conservative buffers. Different airlines may have shorter/longer MCTs at the same airport.

😴 Jet Lag Calculator

Source: Circadian rhythm research from NIH/NHLBI, Sleep Foundation, and peer-reviewed chronobiology literature. Time zone calculations via native browser Intl API.

Update frequency: Annual review of research. Accuracy: Recovery estimates are personalized averages; individual recovery rates vary by age, fitness, and travel history.

Editorial standards

  • Independent. Tools don’t promote specific partners. Recommendations are based on traveler experience and editorial evaluation.
  • Verifiable. Every claim in a tool’s content is linked to a source where possible.
  • Corrected promptly. Report errors at corrections@packzup.com — we fix within 1-2 business days for confirmed issues.
  • No AI-only content. All tool data and editorial content is human-reviewed.
  • Conflict of interest. Affiliate links (e.g. Wise, Charles Schwab) are disclosed; our recommendations would be the same without them.

Versioning

Each tool has a quietly-tracked version. Major changes (algorithm updates, new data sources, expanded coverage) are noted in our changelog. Current platform version: v14 (Enterprise Maturity).

Reporting issues

If you spot inaccurate data, broken functionality, or unclear results:

  • Email hello@packzup.com with the tool name + URL + what you saw vs. what was expected.
  • For visa/legal issues: also share the official source you’re comparing against.
  • For exchange rates: include the rate you saw + the date/time + your bank’s quoted rate.