# Inspector Score The **VitalSentinel Inspector Score** (shown on the score card and often shortened to **Inspector Score**) is a single 0–100 number summarizing the health of an inspected URL across five weighted pillars. It appears at the top of every completed inspection as a gauge, with a per-pillar breakdown below it. The score also maps to a letter grade (A–F) that this page uses to describe score ranges; the card itself shows the number, not the letter. ## Pillars [#pillars] The score starts at 100. Issues subtract from one of five pillars, each with a fixed point budget: | Pillar | Max Points | What it measures | | ------------------ | ---------- | ------------------------------------------------------------------------ | | **Performance** | 40 | Core Web Vitals, page weight, code efficiency, main-thread health | | **SEO** | 25 | Crawlability, on-page fundamentals, JS rendering parity, structured data | | **Security** | 20 | TLS/SSL, security headers, content security, cookie hygiene | | **Infrastructure** | 10 | Caching, compression, protocol version, operational maturity | | **Availability** | 5 | HTTP status, response time | Each pillar contributes independently up to its cap. A page with poor performance but perfect security cannot score 0 - security still contributes its full 20 points. The pillar card on the detail page shows each pillar's percentage, its score out of the pillar budget, and a status word with a color band: | Pillar % | Color | Status | | -------- | ----- | --------------- | | 90–100% | Green | Looking great | | 50–89% | Amber | Room to improve | | 0–49% | Red | Needs work | ## Grade Bands [#grade-bands] The numeric score maps to a letter grade: | Score | Grade | Meaning | | ------ | ----- | ------------------------------------------------------------------ | | 90–100 | **A** | Excellent - meets best practices across all pillars | | 75–89 | **B** | Good - minor issues that don't materially harm users | | 50–74 | **C** | Needs work - multiple warnings or one critical issue | | 25–49 | **D** | Poor - critical issues across multiple pillars | | 0–24 | **F** | Failing - page is broken, insecure, or invisible to search engines | ## How Deductions Work [#how-deductions-work] Every issue carries a **severity** that caps how much a single occurrence can deduct from its sub-pillar: | Severity | Max deduction per issue | | ------------ | -------------------------------- | | **Critical** | up to the full sub-pillar budget | | **Warning** | 4 points | | **Info** | 1.5 points | When several issues hit the same sub-pillar, **diminishing returns** apply - the second issue costs 75% of the first, the third costs 75% of the second, and so on. This prevents a stack of minor problems in one area from disproportionately tanking the score, while still rewarding fixes for the worst issue first. The sub-pillar score is floored at 0 - it never goes negative. ## Fatal Penalty [#fatal-penalty] Some failures are catastrophic - an expired SSL certificate, a 5xx server error, a `noindex` directive - and a normal pillar deduction wouldn't reflect their real impact. For these, Inspector applies a **multiplicative cross-pillar penalty** on top of the pillar deductions: ``` final_score = round(pillar_sum × 0.85^fatal_count) ``` Each fatal issue knocks an additional 15% off the entire score. | Fatal count | Multiplier | Score 95 becomes | Score 80 becomes | | ----------- | ---------- | ---------------- | ---------------- | | 0 | 1.00 | 95 (A) | 80 (B) | | 1 | 0.85 | 81 (B) | 68 (C) | | 2 | 0.72 | 68 (C) | 58 (C) | | 3 | 0.61 | 58 (C) | 49 (D) | A page can never get a clean A grade if it has an expired certificate or is blocked from search engines, no matter how good everything else is. ### Fatal Issues [#fatal-issues] | Pillar | Fatal rule | Why | | ------------ | --------------------------------- | ------------------------------------------------- | | SEO | `noindex` directive active | Page tells search engines not to index it | | SEO | robots.txt blocks the URL | Crawlers cannot access the page | | SEO | robots.txt blocks Googlebot | Google specifically cannot reach the page | | SEO | Robots directive changes after JS | Search engines may see contradictory instructions | | Security | SSL certificate expired | Browser shows full-page security warning | | Security | SSL hostname mismatch | Browser shows full-page security warning | | Availability | Server returned 5xx | The page is broken | | Availability | Server returned 404 | The page does not exist | A fatal issue also zeroes its own sub-pillar in addition to applying the cross-pillar multiplier. ## Worked Example [#worked-example] A staging site accidentally exposed to production: expired certificate, `noindex` tag, otherwise fine. * TLS/SSL sub-pillar zeroed: `−8` (fatal) * Crawlability sub-pillar zeroed: `−10` (fatal) * Pillar sum: `40 + 15 + 12 + 10 + 5 = 82` * Two fatals → multiplier `0.85² = 0.7225` * Final score: `round(82 × 0.7225) = 59` - Grade C Without the fatal mechanism, a page with two browser-warning failures could still grade B. The penalty makes sure catastrophic problems are never masked by perfection elsewhere. ## Domain Health Is Advisory [#domain-health-is-advisory] WHOIS findings (domain expiring soon, recently registered, privacy enabled) are surfaced as issues but do **not** deduct from the score and never trigger the fatal penalty. Domain registration sits outside the page's technical implementation and has no direct user-experience impact. ## What's Not Counted [#whats-not-counted] * **No bonus points** - the score starts at 100 and only goes down. There are no extra-credit items. * **CrUX no-data is not a penalty** - a low-traffic URL with no field data is flagged as informational only. * **TTFB measured from three angles** (CrUX, Chrome inspector, uptime) is intentionally counted in three sub-pillars without coalescing - a consistently slow server is confirmed from every vantage point. ## Related [#related] How issues are categorized, prioritized, and deduplicated. The six data sources Inspector uses to detect issues.