WhichWeek vs Chronolyze

WhichWeek is the fastest way to know your ISO week number. Open the app and your current ISO week number is front and center — bold, clear, and impossible to miss. No digging through a calendar. No mental arithmetic. Just the week number. WEEK VIEW • Your current ISO week number, large and legible • The exact date range for that week (Monday to Sunday) • Step forward or back through weeks and years with the stepper controls • Tap Today to jump straight back to the current week • Leap year indicator so you never lose track of the extra day DAYS VIEW • Pick any two dates and instantly see the number of days between them • Broken down into full weeks and remaining days • Perfect for project planning, countdowns, and date arithmetic DESIGNED WITH CARE • Pure SwiftUI — fast, native, and responsive • Supports Dynamic Type for accessibility • Full Dark Mode and Light Mode support • Works in portrait and landscape • Available on iPhone, iPad, Mac, and Apple Watch ISO WEEK NUMBERS ISO 8601 defines week numbering used widely in business, finance, logistics, and project management across Europe and beyond. Week 1 is the week containing the first Thursday of the year. WhichWeek follows this standard precisely. NO ADS. NO TRACKING. NO SUBSCRIPTIONS. WhichWeek is a one-time purchase. No accounts required, no data collected, no network requests made.

Check whether your mechanical watch runs fast or slow using your iPhone microphone. Measure its rate and beat error, estimate amplitude, and track daily accuracy over time. For microphone measurements, use a quiet room and place the watch case against the phone's microphone. Chronolyze listens to your watch's ticking and displays a classic timegrapher trace — no bench equipment or clip-on sensors needed. Results depend on the watch, microphone contact, and background noise; the signal-quality meter helps you assess the reading. LIVE MEASUREMENT • Rate in seconds per day — is your watch running fast or slow? • Beat error in milliseconds — is the balance swinging symmetrically? • Estimated amplitude in degrees — how far does the balance wheel swing? Requires the correct lift angle and a clear signal • Stability — how steady the rate is holding, so you can tell a settled movement from a restless one • Automatic beat-rate detection from 12,000 to 36,000 bph • Classic two-line timegrapher trace: slope shows rate, gap shows beat error • Signal-quality meter so you know when to trust the numbers • A plain-language verdict on every finished measurement, and a report card you can share ACCURACY TRACKING Track how your watch keeps time in daily wear. Tap along with the seconds hand every few days and Chronolyze calculates its average daily gain or loss between readings. Compare that history with your microphone measurements. Differences can reflect position and wearing conditions; a single comparison does not establish the cause. No microphone needed, so it works even for watches too quiet to measure. POSITIONAL TEST Measure in the six regulation positions — dial up, dial down, crown up, down, left, right — with a guided workflow. Compare the highest and lowest measured rates to see how position affects your watch's timekeeping. Save the results for future checks or to discuss with a watchmaker. MAGNETIZATION CHECK Check for signs of magnetization using your iPhone's magnetometer. Keep the phone still while taking a baseline and scanning the watch. Nearby magnetic objects can affect the reading; this check cannot confirm that the hairspring is magnetized or establish why a watch runs fast. The app does not demagnetize watches. WATCH COLLECTION Keep a watch box in your pocket: per-watch lift angle and beat rate, full measurement history, saved positional runs, accuracy readings, and re-viewable traces for every session. Everything syncs through your own iCloud account, so your collection follows you to every device. BUILT FOR WATCH PEOPLE • A library of 104 movements — Seiko, ETA, Sellita, Miyota, Rolex, Omega, Longines, Citizen, Hamilton, Grand Seiko, Tudor and more — each with the right lift angle and beat rate already set • Set the lift angle by hand for anything not listed (default 52°); amplitude estimates depend on this setting • Pin a nominal beat rate for unusual movements • Dark, instrument-grade interface with iOS 26 Liquid Glass design • Demo movement mode so you can explore every feature without a watch • An animated escapement in Settings that shows exactly what you're hearing WHAT YOU NEED A quiet room and a mechanical watch (hand-wound or automatic). Microphone measurements do not support quartz watches. For best results, rest the watch case directly against the bottom edge of the phone. Whether you're comparing positions, tracking a favorite watch, or preparing questions for your watchmaker, Chronolyze brings measurements and accuracy history together on your iPhone.