Data methodology

What FillUpWatch measures.

FillUpWatch records anonymous observations of completed public pump displays after the driver has left: station, city, state, fuel grade, total paid, and gallons pumped. Per-gallon price is calculated from the reported total and gallons.

What it does not measure

These observations are not a representative consumer survey, an inflation index, or a measure of any individual person. A fill-up total varies with tank size, fuel grade, how empty the tank was, and where contributors choose to report.

Display thresholds

States remain neutral on the map until they have at least five observations. That threshold reduces noise; it does not establish statistical representativeness. Location pages will be indexed only after they have sufficient real coverage and a clear reporting period.

Data integrity

• Submissions require human verification and are rate-limited.
• Totals, gallons, fuel grades, and derived prices are validated for plausible ranges.
• We do not publish personally identifying information.

Use FillUpWatch as a community-sourced signal, not as financial, economic, or purchasing advice.