Seattle Pizza Index (SPI) tracks changes in pizza prices over time using a consistent, transparent methodology. The goal is to observe price trends in a familiar everyday item that touches the lives of everyone in Seattle.
Index Overview
SPI is indexed to a baseline value of 100 as of January 1, 2026. All future values represent percentage changes relative to that baseline. Prices are updated quarterly.
What We Track
SPI tracks two standardized pizza types: the closest available equivalent to a plain cheese pizza and a plain pepperoni pizza. For whole pies, we record the menu price for the closest available size to 16 inches. Where an exact 16-inch option isn’t offered, we use price per square inch to normalize to a 16-inch equivalent, allowing consistent comparison across restaurants. We also record by-the-slice prices where available. This produces two parallel indexes — SPI-P and SPI-S — which can be viewed independently on the chart. No additional toppings, substitutions, or customizations are included.
Restaurant Basket
SPI tracks a fixed basket of 20 pizzerias located within Seattle city limits, spanning a range of neighborhoods, styles, and price points. A separate comparison group of 4 pizzerias outside Seattle city limits is tracked for contextual reference but is not weighted into the core index. Changes to the basket are made sparingly. When a restaurant is added, removed, or replaced, that change is documented here.
Price Definition
All prices reflect pickup orders only, recorded before sales tax. Delivery fees, service charges, tips, and promotional discounts are excluded. Prices are captured exactly as listed on published menus at the time of observation.
Data Sources
Prices are collected from online menus published by restaurants, including official websites and third-party menu platforms. Each observation is recorded with the date collected and a source URL. SPI does not rely on in-store pricing, anecdotal reports, or user-submitted data.
Index Construction
For each update period, prices are averaged across the basket to produce a composite price. That composite is then indexed relative to the January 1, 2026 baseline of 100. SPI shows direction and magnitude of price change — not absolute price levels or quality.
Limitations
SPI does not adjust for inflation, control for portion size beyond stated diameter, account for differences in quality or ingredients, or attribute price changes to specific policies. It is intended to function as a factual reference point.