SummitPlateDataset methodology
Grocery Price Index methodology
How the SummitPlate Family Dinner Cost Index is built: official sources, exact series IDs and units, update cadence, missing-data handling, SummitPlate estimate boundaries, revision policy, and reuse terms for journalists, analysts, and product teams.
Purpose of this methodology
This page is the canonical methodology for the Grocery Price Index dataset. The site-wide editorial methodology page covers content standards across SummitPlate. It is not a substitute for this dataset-specific documentation.
The index turns public U.S. food-price data into a practical family dinner signal: grocery CPI, restaurant CPI, selected staple prices, and SummitPlate planning estimates for a basic home dinner for four and a casual takeout dinner for four.
Official sources
Every monthly update cites the same public sources. BLS provides the CPI and average retail price readings used in the time series. USDA ERS provides Food Price Outlook context and forecasts used in narrative interpretation, not as a replacement for BLS series values.
U.S. Bureau of Labor Statistics CPI and average retail food price series
Official CPI food-at-home and food-away-from-home indexes plus U.S. city average retail price series for eggs, ground beef, boneless chicken breast, milk, and white bread.
BLS Public Data API
Series used: CUUR0000SAF11, CUUR0000SEFV, APU0000708111, APU0000703112, APU0000FF1101, APU0000709112, APU0000702111.
USDA Economic Research Service Food Price Outlook
Monthly context for grocery and restaurant food price trends and annual food price forecasts. USDA ERS summary findings are used to separate observed BLS readings from forecast context; each monthly report states the official data window and forecast release it uses.
Series IDs and units
Official BLS series used in the Family Dinner Cost Index. Index series use the 1982-84=100 reference base. Average price series use U.S. city average dollars for the stated unit.
Update cadence
SummitPlate refreshes the Grocery Price Index when new official BLS food-price readings are available for the tracked series, and when USDA ERS Food Price Outlook context changes the monthly family-dinner interpretation.
The public hub and downloadable CSV/JSON routes share one compiled dataset. The updatedAt field on the JSON download is the SummitPlate compilation date, not the BLS reference month. Each monthly report also records the official data window it uses (for example, “latest BLS food price data available as of July 1, 2026: May 2026”).
Durable download URLs:
Missing-data policy
If a tracked BLS series has no published value for a month, SummitPlate does not invent a reading. The time series skips that month rather than interpolating or carrying the prior value forward as if it were observed.
Example: October 2025 was unavailable in the public series used for this index, so charts and downloads move from September 2025 to November 2025 without fabricating an October point.
When BLS revises a previously published value, SummitPlate updates the affected month in the next index refresh and notes the change in the monthly report when the revision is material to the family-dinner narrative.
SummitPlate estimate boundaries
The following fields are official source data (or direct transforms of those series): food-at-home CPI, food-away-from-home CPI, eggs per dozen, ground beef per pound, chicken breast per pound, milk per gallon, and white bread per pound.
The following fields are SummitPlate planning estimates, not BLS series and not government forecasts:
- homeDinnerForFour — a basic planned dinner at home for four people, used to make the monthly grocery-price signal actionable for weeknight planning.
- takeoutDinnerForFour — a casual takeout or restaurant dinner for four, used as a comparison fallback cost.
- homeVsTakeoutSpread and takeoutToHomeRatio — derived from those two SummitPlate estimates.
Estimates are illustrative planning figures for a typical U.S. family-of-four dinner context. They are not household-specific budgets, regional price quotes, or guaranteed grocery receipts. Do not report them as official BLS or USDA statistics.
Revision policy
The durable CSV and JSON URLs always serve the current compiled dataset. Historical monthly blog posts remain available as point-in-time narratives, but the downloadable series is the living source of record for re-use and charting.
Material revisions include: BLS source-value corrections, changes to which series are tracked, changes to estimate definitions, or corrections to SummitPlate calculation errors. When a revision changes interpretation, the latest monthly report and this methodology page are updated.
Non-material presentation edits (copy polish, layout, internal linking) do not require a dataset version bump.
Citation and reuse terms
You may copy, redistribute, and adapt the SummitPlate-authored compilation, estimates, methodology text, charts, and published embed, including for commercial use, provided you retain the required attribution. This permission does not cover SummitPlate application source code. Underlying BLS and USDA source values remain subject to those agencies' terms and must be attributed to the original sources.
SummitPlate-authored work
The dataset packaging, monthly Family Dinner Cost Index compilation, planned-home-dinner and casual-takeout estimates, narrative takeaways, methodology page, embed chart, and press materials are SummitPlate-authored works.
Underlying public-source data
BLS CPI and average retail food price series values, series identifiers, and USDA ERS Food Price Outlook context are public-source data from the U.S. government. SummitPlate does not claim ownership of those underlying source values and does not grant a substitute license for third-party government data.
Required attribution
Attribute SummitPlate for the Family Dinner Cost Index compilation and estimates, and attribute BLS/USDA for official source series. Suggested form: SummitPlate. "Family Dinner Cost Index." SummitPlate Grocery Price Index. Include the canonical URL and the original BLS/USDA source links when republishing source values.
License / reuse URL for machine-readable consumers: https://www.summitplate.com/grocery-price-index/methodology#reuse-and-licensing
These reuse terms are not legal advice, are not a warranty, and do not guarantee that every downstream use is permitted under third-party source terms. Users remain responsible for complying with BLS, USDA, and other applicable source requirements.