Methodology & data sources

Data sources

Rolimons item API — values, RAP, ratings

Item names, community values, RAP, demand and trend ratings, and the projected and rare flags come from the public Rolimons item API. We fetch the full catalogue at most once per hour and serve every page from that shared snapshot — pages state when they are running on a cached copy instead of a live fetch.

Coverage limits, stated plainly: only roughly a fifth of catalogue items carry an assigned community value at any given time; the rest are priced on RAP alone and are labelled “RAP only” wherever they appear. A majority of items likewise carry no demand or trend rating; the model treats unrated as neutral, never as negative. Rolimons' values are themselves editorial estimates by their value team — informed judgements, not exchange prices.

Roblox economy API — price history

Price and sales-volume history charts on item pages come from Roblox's own public economy endpoint. Two honest caveats about that feed. First, it is a historical archive: Roblox's public resale series for limiteds stops updating (currently it ends in early 2025), so every chart states its own coverage dates and the change figures are anchored to the end of the feed, not to today. Second, the feed occasionally contains glitched recorded days — a verified example is a 1-Robux average on an item worth hundreds of thousands — so days far outside an item's own median are excluded from charts and statistics, with the exclusion count disclosed on the page. Items that rarely sell return no history at all; those pages say so instead of drawing an empty chart.

Static reference data

The currency converter uses fixed reference rates (Robux retail and DevEx rates, USD/EUR/GBP), with the last-updated date printed on the page. The XP predictor uses approximate community-calibrated curves, labelled as such on the page — they are starting points to override with your own measured rate, not published game formulas.

The trade model

The calculator scores each side of a trade in four steps. All constants are listed below exactly as the code uses them; there are no hidden adjustments.

1. Base price. Each item is priced at its community value where one exists, otherwise its RAP. The verdict's confidence rating drops whenever RAP-only items are involved.
2. Demand and trend weighting. Rated items are adjusted by the multipliers in the table below. The spans are deliberately modest — ratings refine a price rather than replace it.
3. Projected penalty. Items flagged as manipulated are priced at 75% of list (-25%), and their presence forces confidence to low.
4. Bulk discount. Each item beyond the first on a side costs 3.5%, capped at 25% — the mechanical form of the trader's rule that a pile is harder to move than a single clean item.

The two adjusted sides are compared, and anything inside ±5% is reported as fair — value estimates are approximations, and pretending to finer resolution than a few percent would be false precision. A trade with either side empty gets no verdict at all.

How the constants were chosen — honestly

The constants encode widely held trading heuristics — demand moves prices a little, projection ruins them, bulk trades at a discount — at magnitudes set by judgement, not fitted to data. They have not been backtested against resale history, and until they are, that is the model's biggest limitation. We would rather state that than imply a rigour the model does not have. The direction of every adjustment is defensible; the exact size of each is an estimate.

What this site never does

• Invent a value, rating or price. Every figure traces to a source named on this page.
• Present a verdict without disclosing which numbers it stands on.
• Guarantee an outcome. The model is a sanity check, not an oracle — trades are decisions.

Found a number this page cannot explain? That is a bug. Tell us.