Descriptive statistics for any dataset
Paste numbers separated by spaces, commas, or newlines. Get count, sum, mean, median, mode, range, variance/stddev (population and sample), and quartile percentiles.
What the stats mean
Mean is the average. Median is the middle value. Std dev measures spread. Percentiles report where a value falls in the sorted distribution.
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Paste numbers
Comma, space, semicolon, or newline separators all work.
Inputs are treated as UTF-8 throughout the pipeline and validated client-side as you type — nothing dispatches until the value is well-formed.
inpututf-8client-sidevalidatedinput · textnumbers · set12, 18, 7, …
loaded · parsedclient-side - 02
Read center
Mean, median, mode highlight the dataset center.
Each toggle re-computes through a memoised hook, so flipping options never resets your input and the UI stays snappy on large inputs.
centeroptionslivememoisedtogglesmean · memoised14.8 · livemean 14.8
options set · memoisedlive - 03
Read spread
Range, variance, stddev describe how spread out the data is.
Randomness — where used — comes from
crypto.getRandomValues, neverMath.random. Heavy work sits inuseMemo.spreadcomputeinstantlocaldeterministicstddev · instant5.7 · computedσ ≈ 5.7
computed · instantinstant - 04
Read tails
P25, P50, P75 quartiles; P90/P99 for tail behavior.
Copy writes through
navigator.clipboardand downloads use aBlob— zero network traffic. Same input plus same options always yield the same bytes.tailscopydownloadzero-networkreproducibleok · copiedP75 · copiedP75 = 18
shipped · ready to shipsuccess
Pro tips for everyday utilities
Reach for crypto.getRandomValues
Cryptographically random for IDs, tokens, salts. Math.random is for animation and games, not security.
Mock data with seeds
Faker-style libraries can be seeded so tests are reproducible. Embed the seed in the fixture file.
Reference cards beat memory
Cheatsheets for Vim, Git, Docker, Linux signals are faster than man pages when you’re mid-flow.
Browser APIs vary
Touch events, gamepads, and clipboard differ across vendors. Feature-detect before use.
Persist in the right place
localStorage for user preferences, sessionStorage for transient state, IndexedDB for structured data.
When to crunch stats
Reports, A/B test summaries, smoke checks.
Latency reports
Quickly see P50/P90/P99 for a response-time dataset. Random values come from crypto.getRandomValues — cryptographically secure for tokens, salts, and session IDs. Math.random is deterministic enough for animations but predictable enough to be a security bug.
CSPRNG-backedSurvey data
Mean and std dev of Likert responses. Pair with hashids, ULID, or UUID v7 when you need both random and sortable — useful for primary keys, public-facing IDs, and event log ordering without a sequence column.
reproducibleA/B test sanity
Compare two control samples without firing up Excel. Output is deterministic given the same seed, so fixtures and tests stay reproducible across CI runs and contributor machines. Embed the seed in the fixture file for full replay.
snappyBuild times
Track CI duration variability over time. Heavy work runs through useMemo so the UI stays snappy on large inputs. Same input + same options yields identical bytes — the kind of stability snapshot tests rely on.
feature-detectedClass grading
Score distributions for a single test. Storage tools persist to the right backend: localStorage for user preferences, sessionStorage for transient state, IndexedDB for structured data. Pick the right shelf and quota worries disappear.
deterministicSensor readings
Quick descriptive stats on IoT data. Browser feature detection: clipboard, fullscreen, gamepad, and Web Bluetooth APIs gracefully fall back when unavailable. No surprise white screens on Safari or older Firefox.
production-readyFrequently asked questions
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