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About
Reckon is a precision unit converter. Thirteen categories (length, weight, volume, temperature, time, cooking, energy cost, tire pressure, body temperature, pace, percentage, currency, and a set of date tools) are free forever. One $2.99 unlock adds 30 more specialist, engineering, and scientific categories, plus deeper sub-modes like Cooking Density, Radioactivity Decay, and historical currency rates, conversion history, and favorites.
Every screen offers three keypads (Basic with expression entry, Scientific, and Numeric) you can switch on the fly, and any result can be copied with a long-press.
Live currency conversion is free; historical rates back to 1999 are a Pro feature. Currency is the only category that ever uses the network; every other category works fully offline.
Japanese traditional units (shaku, sun, ken, ri, kan, monme, tsubo, jō, shō, gō, koku) are first-class throughout, not bolted on.
Reckon is on Google Play now and is coming to the App Store for iPhone and iPad (iOS and iPadOS 15 or later). The Pro unlock is a one-time purchase on whichever store you buy it from; because each store handles its own purchases, an unlock bought on Google Play does not carry over to the App Store, or the reverse.
What it does
- 43 categories spanning everyday, specialist, engineering, and scientific units
- Three keypads (Basic, Scientific, Numeric) with expression entry and per-screen switching
- Japanese traditional units throughout
- Free live currency conversion with a three-tier provider chain (USD-pinned); historical rates back to 1999 are Pro
- Fully localized in 20 languages
- No ads, no account, no analytics
What you get free, and what the $2.99 unlock adds
Free
- Length, Weight, Volume, Temperature, Time, Cooking, Energy Cost, and Date tools
- Tire Pressure, Body Temperature (with fever annotations), Pace ↔ Speed, and Percentage
- Live Currency: current rates with a three-provider failover chain and 24h cache
- Date tools: age from date of birth, days between dates, date ± N days
- Three keypads (Basic with expression entry, Scientific, and Numeric), switchable per screen, with a default in Settings
- Single or multi-unit display; long-press any result to copy it; Light / Dark / System theme
Pro · $2.99 one-time
- Area, Speed, Energy, Power, Pressure, Fuel Economy, Data, Frequency, Angle, Base / Numeric, SI / IEC Prefix
- Engineering set: Force, Torque, Density, Sound, Concentration, Flow Rate, Concrete & Construction, HVAC
- Scientific set: Heat Density, Moment of Inertia, Illuminance, Magnetism, Electric Charge, Radiation (with isotope decay and half-life), Astronomical Units
- Pixel Density & Resolution, Survey & GIS, and a Cooking Density sub-mode with per-ingredient tables
- Clothing Size and Shoe Size (US / UK / EU / JP)
- Currency Historical: exchange rates from any date back to 1999
- Last 50 conversions in history; up to 20 favorites
Languages
Reckon is fully localized in 20 languages: English, Chinese (Simplified), Chinese (Traditional), Dutch, French, German, Hindi, Indonesian, Italian, Japanese, Korean, Polish, Portuguese (Portugal), Portuguese (Brazil), Russian, Spanish (Spain), Spanish (Latin America), Thai, Turkish, Vietnamese.
Accuracy and limitations
Reckon's Currency category shows daily reference exchange rates from public providers (primarily the European Central Bank feed), not live interbank or trading rates, and it caches them for up to 24 hours; historical rates use the same daily-reference basis. Use them for everyday estimates and conversions, not for trading, settlement, or any decision that needs to-the-second pricing. Body Temperature shows informational status labels (such as normal, fever, or high fever) beside a reading; these are guidance only, not a medical diagnosis. Most other categories are exact unit math. Apparel sizing (Clothing and Shoe Size) maps published regional size charts; real garments vary by brand and cut, so a brand-variation note appears beneath every sizing result.
Privacy at a glance
- No personal data is collected by Reckon.
- All app data is stored on your device.
- No analytics, no telemetry, no crash reporting.
- No account is required to use the app.
Read the full Reckon privacy policy or learn about account and data deletion.
Permissions Reckon requests
- Internet · Android only
- Used by the free Currency category and the Pro Currency Historical sub-mode to refresh exchange rates from one of three providers (api.frankfurter.dev, open.er-api.com, or cdn.jsdelivr.net), and to verify your purchase with Google Play. Every other category works fully offline. On iPhone and iPad, network access needs no permission.