Methodology
Every conversion on Convertitive comes from a published source — NIST, BIPM, the European Central Bank, WHO, a peer-reviewed paper. The pages below explain which authority drives which result, what the exact formula is, and where the precision limits sit. Read before citing a Convertitive number anywhere it has to be defensible.
Units methodology
NIST SP 811, BIPM SI Brochure, 1959 yard-and-pound agreement. The hub-and-spoke factor architecture and where the precision floor sits.
Math methodology
Percentage formulas, area (Heron's formula), descriptive statistics (sample vs population, NIST linear percentile).
Date & time methodology
Calendar-aware age borrowing, IANA tzdata via Intl.DateTimeFormat, ISO 8601 conventions throughout.
Finance methodology
Amortising-loan derivation, compound-interest formula, tip + tax + discount math. Standard banking math + first-principles algebra.
Health methodology
BMI (WHO ranges + Quetelet's index), BMR (Mifflin-St Jeor 1990), body fat (US Navy NHRC 1984), pregnancy due date (Naegele's rule).
Currency methodology
ECB reference rates via Frankfurter, ISR cache, mid-market rate, retail spread economics.
Color methodology
sRGB anchor, gamma curve, deterministic HEX/RGB/HSL/HSV round-trips.
Code tools methodology
Base64 RFC 4648, JWT inspection (no verification), Web Crypto hash primitives, crypto-strong randomness.
Crypto methodology
Wei/Gwei/ETH conversions in BigInt — exact integer arithmetic past JavaScript Number's precision floor.
Sizes methodology
Brannock-derived US shoe sizes, Mondopoint, modern bra band rounding, ring-diameter anchor.
Image format methodology
Canvas API + browser-native encoders. PNG/JPG/WebP quality handling, browser-only privacy.
AI tokens methodology
Character-ratio heuristics, BPE tokenisers, pricing refresh cadence. Why estimates differ from real bills.
Design methodology
Aspect ratio via GCD reduction. DPI as a per-axis quantity with device presets fallback.
Cooking methodology
Per-ingredient density data, the regional cup volume problem, and why baking depends on weight.
Fuel economy methodology
Through km/L as canonical anchor. Why L/100km isn't linear with MPG and the MPG illusion that follows.
API methodology
Public, CORS-enabled, no API key. The deliberate design choices behind /api/v1/.
Age calculation methodology
Calendar borrowing, not naive 365.25 division. The Feb 29 problem and how the calculator handles it.
More pillars coming over the next quarter — see our about page for the publishing rhythm.