What a GEX Calculator Actually Computes
Every product in this category runs the same arithmetic. Take each contract's gamma, multiply by open interest and the contract multiplier, scale by spot, sign calls positive and puts negative, and sum. That is it. Our GEX formula walkthrough takes the expression apart term by term, and there is nothing proprietary in it.
What separates one calculator from another is the four decisions made around the arithmetic: which chain the open interest came from and how stale it is, how many expirations were included, which unit the output is quoted in, and whether the dealer sign assumption was disclosed or quietly assumed. Two competent builds using identical formulas routinely produce different call walls because they answered those four questions differently. Neither is wrong. But if you cannot find out how a vendor answered them, you are reading a number you cannot audit.
How to Evaluate One
Methodology transparency
Ask whether the vendor states, in public, on its own site, how it calculates the number. Barchart does: its per-ticker gamma exposure pages specify "4 nearby expirations, based on a 1% move of the underlying security using gamma and open interest," sourced from the consolidated options feed. That single sentence tells you more about what you are looking at than a page of marketing. Vendors that describe their levels only as proprietary are asking for trust you have no way to calibrate.
Unit convention
The two standard quotes differ by a factor of spot × 0.01. On SPX near 7,700 that is 77, so the same book quoted per-$1 and per-1% differs seventy-sevenfold, and neither figure is incorrect. Michael Perfiliev's widely copied walkthrough states the conversion explicitly, "Option's Gamma * Contract Size * Open Interest * Spot Price ^ 2 * 0.01", and reports results in billions per 1% move. If a chart shows an unlabelled axis, its magnitude is uninterpretable, and comparing it against a second vendor's figure is meaningless.
Open interest freshness
Open interest settles overnight. A calculator reading a live intraday chain is working from yesterday's settled figures plus whatever the feed reports, and a calculator reading a morning settlement file is working from the same underlying numbers with the staleness made explicit. The failure mode worth knowing about is a chain that returns open interest of zero on every row: gamma times zero is zero, so the pipeline does not error, it produces a confident, well-formed, entirely fictional result. We hit exactly that and documented it, because a GEX pipeline fails silently far more often than it crashes.
Sign-convention honesty
Open interest proves a contract exists. It does not reveal which side of it a dealer holds. Every public-data calculator resolves this by assuming dealers are long calls and short puts. Free chart pages that disclose the assumption state it directly: options liquidity providers are treated as short puts and long calls. Treat the sign as a hypothesis. Where it is wrong, the level was never real. Our gamma exposure primer covers what the profile does and does not imply once built.
Accountability
This is the criterion almost nobody applies, and the reason this list is ordered the way it is: can you check the vendor's levels against anything? Ticker counts, update frequencies and model counts are capability metrics, not accuracy metrics. What makes a claim falsifiable is a published method, a capture time on every number, and any rate reported next to the sample and the condition it was measured under rather than on its own. Across the products below that combination is close to nonexistent, worth pricing into the decision. It is also the standard that made us withdraw our own wall hold rate in August 2026: it was measured on a third-party definition of a wall and was dominated by how far that wall sat from spot, and a rate that cannot survive its own conditioning is not evidence.
The Tools, by the Job You Need Done
Pricing and feature detail below was read from each vendor's own public pages on 20 August 2026, except Unusual Whales, which was re-checked on 5 October 2026 and again on 18 October 2026, and the four newer free level pages, which were read on 11 October 2026. These figures move; re-check before subscribing.
Best multi-model level set: MenthorQ
MenthorQ prices Premium at $129/month after a $39 first month, and Pro at $349/month after a $174.50 first month, with a stated seven-day money-back guarantee. Premium advertises "20+ Trading models," 10+ integrations and a large academy library; Pro layers on live trading sessions and weekly mentorship. Its key levels centre on SPX, QQQ and VIX, with data spanning stocks, ETFs, indices, crypto and futures. The pitch is breadth of models rather than one canonical gamma number, which suits traders who want several independent level sets to agree before acting.
Best GEX bundled with options flow: Unusual Whales
Unusual Whales runs Retail Basic at $50/mo, Retail Pro at $75/mo and Retail Max at $120/mo. As of October 18, 2026, the pricing page lists SPX market maker exposure with 10-minute exchange-data updates on Basic and Pro, and 1-minute updates on Max, the only card that calls it GEX Periscope. A GEX heatmap covering all US tickers is included on the paid tiers. If you already want the flow product, the 10-minute exposure view comes with the $50 Basic tier. (Correction, October 18, 2026: an earlier version of this paragraph, based on the October 5 read, said the exposure feed started at Pro and was not on Basic.)
Best dedicated GEX dashboard at the low end: GEXBoard
GEXBoard prices Starter at $19/mo, Pro at $39/mo and Trader at $79/mo during a beta that the page says ends 1 October, with regular rates of $39, $79 and $149. Starter covers ten tickers and weekly plus monthly expirations; Pro extends to thirty tickers including SPX and all DTE modes with a heatmap and wall migration; Trader adds DEX, vanna and charm profiles plus a 30-day GEX history. The page states that "GEX levels recalculate continuously throughout the trading day using real-time options chain data and live spot prices," and also that "We don't offer free trials."
Best free per-ticker screen: Barchart
Barchart's gamma exposure pages are viewable without an account, cover indices, stocks and ETFs, and state their method openly, as noted above. The page says gamma exposure "is calculated and updated throughout the day." For scanning where gamma sits on an arbitrary single name, this is the fastest free answer available, and the disclosed methodology means you know what you are comparing.
Best DIY build: Perfiliev's walkthrough
Perfiliev's guide is free and reproducible end to end: pull the exchange's delayed-quotes options chain as a CSV, pivot strike against total gamma in Excel, then move to Python for the full gamma profile. Building it once is the cheapest way to learn which assumptions every commercial dashboard is making on your behalf, and the cost is an afternoon.
Newer free level pages, checked 11 October 2026
Four tools that publish GEX levels for free, each described from its own page:
- GEXMetrix: a free GEX levels page with zero gamma, call wall and put wall for 12 symbols (SPX, NDX, SPY, QQQ and eight single names), "recomputed every 15 minutes from delayed data. No login required." Its free dashboard tier adds what it calls an Intraday OI Model on delayed exchange data.
- ZeroGEX: its pricing page marks delayed levels for six symbols (SPX, SPY, QQQ, NDX, ES and NQ), TradingView and thinkorswim scripts, and the same levels in AI assistants over MCP as "Free for everyone, no account needed." Real-time levels are on paid plans, with Basic at $39 a month billed monthly.
- WyckFlow: free daily gamma levels for NQ, ES and COMEX gold futures, computed from index and GLD option chains, about 15 minutes delayed, "Free, no sign-up." Built for futures traders; the paid product is a MotiveWave study.
- GEX Levels: a free Morning Map on its home page, yesterday's NQ and ES dealer levels every trading day, no account. Its per-ticker pages explain the levels without live numbers; the live map is in a paid indicator from $9.99 a month.
Best free, no-signup SPX levels with a published method: SquawkFlow (that's us)
Our SPX gamma exposure page needs no account and is free. The walls come from a full-chain snapshot built each morning before the open: settled open interest across roughly 21,000 listed SPX contracts, crossed with per-contract implied volatility. Because the input is settled open interest, the walls are fixed for the session by construction, a refresh every 30 minutes repoints spot, the expected range and the 0DTE magnet, not the walls. Two things are unusual here. First, every number ships with the time it was captured and the settlement date its open interest came from, and the overnight change in that open interest is published as a count from our own archive rather than an estimate. There is no wall hold rate: we showed one until August 2026 and withdrew it, because it was measured on a third-party definition of a wall and was dominated by distance. Second, an intraday session log records structural changes as they happen, timestamped rows tagged RELOCATION, FLIP CROSS, REGIME, TEST or QUIET, each with the spot print and a plain description of what the levels did, with no directional call attached. Our method note documents the pipeline including the zero-open-interest bug that once made it serve $0. Beyond SPX, the per-ticker pages publish dealer gamma and key levels for 200+ US stocks and ETFs, and the SPX GEX heatmap shows gamma by strike and expiration. All of it is free, with no signup and no daily limit (checked 11 October 2026). If you need intraday dealer flow or intraday single-name positioning, the paid products above are the right tools.
How to Shortlist
Work backward from the decision. Intraday SPX positioning wants a genuine intraday flow product, a paid one such as Unusual Whales' one-minute exposure view. Single-name gamma across a watchlist wants breadth, so Barchart free or GEXBoard paid. Daily SPX levels you intend to mark on a chart before the open need accuracy over frequency, so read the published method and the capture time before the refresh rate. And if you are still deciding whether gamma belongs in your process, build it once from the delayed option chain and compare your output against two free dashboards; our checklist for reading a free gamma exposure chart is the fastest version of that exercise. Why published dashboards disagree at all is covered in SPX gamma levels.
The Mistakes That Cost the Most
Comparing two vendors' numbers without checking their units is the expensive one, and the factor of 77 makes it look like a data error rather than a convention mismatch. Treating the dealer sign assumption as observed fact is the second, it is a modelling convention that is roughly right for index products and sometimes wrong for single names around events. And the most persistent is confusing update frequency with accuracy. A level recalculated every second from settled open interest is not fresher than the same level computed once at 9am; it is the same number redrawn. What tells you whether it works is a hit rate, which is exactly the statistic almost nobody publishes.
Educational content, not financial advice. See our risk disclosure.