About the EVE Reactions Calculator

Methodology

Every published reaction formula from the EVE Online static data export is evaluated with your settings (structure, rigs, system, skills, market methods, taxes and shipping). All formulas are listed below.

Material modifier = 1 − rig ME bonus × security modifier (T1 2 %, T2 2.4 %; lowsec ×1.0, nullsec and wormhole ×1.1).
Required quantity = max(runs, ⌈round(runs × base quantity × material modifier, 2)⌉).
Time modifier = (1 − 4 % × Reactions skill level) × structure multiplier (Tatara 0.75, Athanor 1) × (1 − rig TE bonus × security modifier) (T1 20 %, T2 24 %).
Runs per cycle = ⌊cycle length ÷ run time⌋, at least 1 and at most the formula's maximum runs.
Job cost = estimated item value × (system cost index + facility tax + SCC surcharge), where the estimated item value is runs × Σ material quantity × ESI adjusted price.
Buying inputs: buy orders pay the broker fee; instant buys pay the sell price; contracts use the buy, sell or split price without fees.
Market depth: with buy orders or instant buys, an input is bought at the input hub only up to the units its sell orders currently list (shared by every job of a chain or plan); the rest is bought at your "Buy missing inputs from" hub (default Jita 4-4) with the same method and fees. Contracts and past prices are not split.
Selling outputs: sell orders pay broker fee + sales tax; instant sells pay the buy price and sales tax; contracts pay no fees.
Home page lists only show products the market can take: one slot's daily output must be at most 10% of the units traded per day (30-day average) in the output hub's region. The change next to the volume compares the last 7 days with that average.
Shipping = (quantity × volume × ISK per m³ + quantity × unit price × collateral %) × (1 − discount %), for inputs and outputs separately; the discount covers e.g. a volume discount from your hauling service.
Chains build every intermediate that is itself a reaction product (each with its own reactor settings). The chain slot allocation (Settings) decides how they occupy slots: single slot runs one line of the chain job after job in one slot, and profit per slot-day = profit ÷ the summed job time in days; optimal slots runs 1 to Max parallel lines (setting, default 4) parallel lines of the final product (or a line count you pick on the reaction page) and gives every reaction ⌈runs ÷ runs per cycle⌉ slots, picking the line count with the highest profit per slot (surplus intermediates count here, as they carry over; within 0.5 %, the fewest lines), and shows one steady cycle after the build-up: profit per slot-day = profit per cycle ÷ (slots × cycle days).
Reprocessing of unrefined products uses your reprocessing yield; Prismaticite outputs use the configured roll between the minimum and maximum quantity.

FAQ

Where do the prices come from?: Market orders are read from the EVE Swagger Interface (ESI) every 30 minutes for Jita 4-4, Amarr, Perimeter, Dodixie, Rens and Hek. When ESI is unavailable the Fuzzwork market aggregates are used as a fallback. Logged-in players can add structure markets their characters can see.
How often are cost indices updated?: System cost indices and adjusted prices are refreshed from ESI as soon as their cache expires (about hourly).
Why is a reaction shown as "n/a"?: At least one input or output has no price at the selected market, so the profit cannot be computed reliably.
What does "profit per slot-day" mean?: Profit divided by the reaction slot-days it takes, so reactions of different length and full chains (which occupy several slots) compare fairly. With single-slot allocation that is the summed duration of every job; with optimal slots it is every allocated slot × the cycle length.
Is chain surplus counted as profit?: No. Leftover intermediates from building a chain are listed separately and valued at the output market, but they are not added to the profit.
Can I use the data in my spreadsheet?: Yes, see the API page. Profits, prices, price history and cost indices can be fetched as CSV (format=csv) for Google Sheets IMPORTDATA.
Does the site use cookies?: The site sets only functional cookies: your theme choice, your calculator settings once you save them on the Settings page (just the values you changed from the defaults; "Reset to defaults" removes it) and, when you log in, a session cookie plus a short-lived one during the EVE login. Settings you changed on the old version of the site are carried over once into the new settings cookie, and the old cookies are removed.

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