Development

Convert Unix timestamps between hexadecimal and decimal/ISO — paste 0x5F6B3A2F, a bare 8-digit hex value, decimal seconds or milliseconds, or a date, and get every form back.

Development

Generate RFC 9562 UUIDs — including the modern v6, v7 and v8 that most generators lack — or decode any UUID back to its version, variant and embedded timestamp.

Text Processing

Run the UAX #9 Unicode bidirectional algorithm rule by rule — X1–X8 embedding levels, isolating run sequences, BD16 paired brackets with N0, W/N/I resolution and L1/L2/L4 reordering — and inspect every intermediate state.

Science & Education

Rectangular-barrier WKB T ≈ e^(−2κa) vs exact transmission, reflection R = 1−T, and over-barrier partial reflection for electron, proton, or custom mass.

Science & Education

Δx·Δp ≥ ℏ/2: minimum Δp from Δx, minimum Δx from Δp, or a pair check with satisfaction ratio. Units m–pm and kg·m/s / g·cm/s / eV/c; optional mass derives Δv.

Math & Numbers

Complete truth table (≤ 6 variables, 64 rows) with alphabetical variable order, per-row function values, and canonical Σm/ΠM forms.

Health

Per-step and mean trophic transfer efficiencies from measured level values, with band grading, weakest transfer, and next-level projection.

Development

Decode lexically sortable IDs losslessly with BigInt: ULID (Crockford base32), KSUID (base62), NanoID, MongoDB ObjectId, and Discord/Twitter/Sonyflake Snowflakes — with ISO timestamps, raw hex, bit-level field breakdowns and birthday-bound collision probabilities.

Health

Convert BUN (mg/dL) to/from urea (mmol/L). Factor 0.357 (urea molar mass 60.06, BUN counts 2 N = 28.014). Derived from Young 1987, StatPearls, KDIGO 2012. Not medical advice.

Health

Calculate the Urea Reduction Ratio (URR) for a single hemodialysis session: URR (%) = (Pre-BUN − Post-BUN) / Pre-BUN × 100. KDOQI recommends a minimum URR ≥65% and a target dose ≥70%. URR is a simple adequacy marker but is being phased out in favor of Kt/V, which also accounts for urea generation and volume contraction. Derived from the KDOQI Clinical Practice Guideline for Hemodialysis Adequacy. Valid for single hemodialysis sessions with BUN drawn pre- and immediately post-treatment; not for peritoneal dialysis. Not medical advice.

Health

Empiric starting dosing for vancomycin per the 2020 ASHP/IDSA/PIDS/SIDP consensus guideline. Loading dose: 20–25 mg/kg actual body weight (obesity cap 3000 mg). Maintenance dose: 15–20 mg/kg actual body weight every 8–12 h. Optional creatinine clearance (CrCl) input suggests an empiric dosing interval (≥90 → q8h, 50–89 → q12h, 30–49 → q18–24h, 10–29 → q24h, <10 → q24–48h). Optional measured trough is classified against the SECONDARY trough target of 15–20 mg/L. The 2020 guideline shifted the primary monitoring target to AUC₀₋₂₄/MIC = 400–600 mg·h/L (within first 24–48 h); trough-only monitoring is no longer recommended as primary. Derived from Rybak MJ et al., Am J Health-Syst Pharm 2020. Empiric start doses ONLY — individualize by AUC-guided Bayesian monitoring. Not medical advice.

Health

Predict the trough concentration Cmin from a measured peak concentration Cmax during therapeutic drug monitoring (TDM): Cmin = Cmax · e^(-kτ), where k = ln2 / t½ and τ is the time from the peak to the next dose. Inputs are the measured peak, the elimination half-life, and the dosing interval. Also reports the fraction of the peak remaining at the trough and the peak-to-trough drop. This tool takes a measured Cmax (the TDM workflow), unlike drug-half-life-dose (which derives C0 from Dose/Vd) and dosing-interval-designer (which outputs a dimensionless peak/trough ratio, not an absolute concentration). Valid for one-compartment first-order elimination with the peak measured post-distribution. Not medical advice.