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).
Planner: the targets start together and every intermediate runs in the cycle before the job using it, so a chain is steady after one cycle per level. Stock you hold of an intermediate feeds the earliest cycles first: its reaction starts later or runs fewer runs in its first cycle (and so do the reactions feeding it), and the targets can start sooner. The build-up never takes longer than without stock. Stock of a bought material covers the earliest start-up purchases. Stock is valued at market price: it lowers the initial investment (start-up purchases and job costs up to the first steady cycle, plus formulas) but not the profit per cycle. Stock the start-up does not use is listed as not used. The shopping list for a number of cycles (1 to 52) adds up everything those cycles buy; with "Subtract my stock" on, your stock covers its earliest purchases over all those cycles, and stock of an intermediate saves its reaction's runs (and their inputs) in later cycles too.
Use what I have (planner): plans 1 to 12 cycles of reactions (one cycle is one round of jobs of your cycle length; later cycles can use what earlier ones made) that turn the stock you hold into more value, buying nothing but fuel blocks (and formulas, at market price, if you allow formulas you don't own). Items count at their sale value after fees, taxes and output shipping; items without a price count 0. It aims for final products: an intermediate it makes and still holds at the end counts only at what went into it, so intermediates are made to feed later jobs. It maximises what you hold at the end minus the ISK spent on fuel, job costs and formulas, then rebuilds every job with exact material quantities. Fuel blocks you hold are used before buying. The search runs in your browser for the search time you choose (10 to 60 seconds) and shows the best plan found so far while it looks for a better one.
Reprocessing of unrefined products uses your reprocessing yield; Prismaticite outputs use the configured roll between the minimum and maximum quantity.

Profit tracking

When you switch on Profit tracking for a character or corporation, the site reads its industry jobs, wallet, market orders, contracts and blueprints from EVE and works out what your reactions really earned. This data is only visible in your account.

Oldest first. Everything you buy or make becomes a batch. A job uses the oldest batches first, and so does a sale. What a unit cost you is the price of its batch, plus the job cost for what your jobs made.
Sales count after sales tax and broker fees, read from your wallet journal. When the journal does not show them, your calculator settings are used and the sale is marked "estimated".
Contracts with one kind of item give it the contract price. A contract with several kinds of items is split by the Janice appraisal linked in its title, or else by the contract price rule of your profit tracking settings, and is flagged for a check when its total looks off. On the ledger you can give a contract a Janice appraisal link of your own to split it by that appraisal instead.
Inputs without a purchase (for example bought before tracking started) count at their buy value when the job started, marked as an estimate, until you add the purchase or correct the price.
Manufacturing: reaction products used by your manufacturing jobs count either at their buy value on the day the job started or at what they cost you (no profit, no loss), as you choose. Other tracked materials they use, like minerals, leave your batches without counting for any profit or cost.
Fuel blocks you build: a fuel block job uses its ingredients like a reaction uses its inputs, oldest first, and its fuel blocks cost what went into them plus the job cost. Your reactions then use those fuel blocks at that cost. Fuel block jobs make no profit of their own and are not counted as reaction jobs.
Material use follows the structure each job ran in, its rigs (a structure fits one rig of each kind) and, for manufacturing, the blueprint's material efficiency. EVE tells most of this; you fill in the rest on the profit tracking settings page. A reaction job whose structure or rigs are not known uses the ME rig of your reactor settings.
Your changes: you can correct any price and add purchases EVE does not know about. Both are kept through later syncs, and the results are recalculated.
Where prices come from: a buy value on a given day is the daily average of the market hub of your contract price rule, or else the average of its region that day, or else the hub's current price. Expected profit values the output you still hold at today's prices with your calculator settings. On the page of a running job it is an estimate: the output the job will make at today's value, less its inputs and job cost.

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.
Does the site use analytics?: Yes: Rybbit, selfhosted, and Cloudflare Web Analytics. They record page views, errors and page speed.

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