AFT Score Calculator

Mobile app that scores the U.S. Army Fitness Test (AFT, formerly the ACFT). Enter your age, sex or combat-MOS standard, and your event results; it returns a score for each event and a total, and shows how that score compares with other users. Published on the iOS App Store as AFT Score Calculator: a 4.8 average (US storefront) and 976 ratings worldwide, with 85,000+ downloads (ratings and downloads as reported in App Store Connect, 2 November 2026; downloads are only visible there).

Why it exists

Scoring the Army Fitness Test means looking up each event's result in tables that depend on age, sex and standard, then adding the events up, and working out what you still need for a target total is more lookups. This app does the lookups on the device (so it works offline), shows each event score and the total, a goal planner for what each event needs to reach a target, and, with an account, how your score compares with other soldiers' saved results.

Features

• AFT Calculator – event scores and total for the current standards, plus a percentile card (see Percentiles)
• Goal Planner – given the results you entered, works out what each event needs to reach a target total
• Waist-to-Height Ratio – body-composition screening
• Accounts and saved results – sign in to save scores and view them later
• Runs on a dark theme; on tablets the screens stay in a readable 640px column

The home screen states the standards are "Current as of 7 July 2026".

Stack

• React Native 0.86 / Expo SDK 57 (JavaScript), React Navigation (native stack)
• expo-dev-client for native builds, EAS for build and submit
• react-native-google-mobile-ads for the banner ad
• Talks to a Django REST API (private repository) for accounts, saved results and percentiles

Running it

npm install
npm start                # expo start --dev-client

This app uses native modules (ads, tracking transparency), so Expo Go will not run it. Build a development client instead:

npm run android          # expo run:android (needs the Android SDK)
npm run ios              # expo run:ios (needs macOS and Xcode)

The android/ and ios/ folders are generated by Expo (expo prebuild) and are not committed.

The calculators work without a server. Sign-in, saved results and percentiles call the backend at the URL in components/constants.js: a local address in development and the production host otherwise. To use your own backend, change backendUrl there and run the backend repo locally.

Tests and checks

npm test          # scoring tests (Jest, no network)
npm run lint      # ESLint with the Expo config
npm run build:check   # bundles the JavaScript for iOS and Android

The same three run on every pull request (.github/workflows/ci.yml). They do not compile native code, so a green check does not prove an iOS or Android build will succeed; that is still done with EAS at release time.

The scoring tests are in tests/: golden values read by hand from the table cells at each threshold and one step either side, an independent reference scorer checked against every table, column and boundary, structural checks on the tables themselves, a cell-by-cell comparison of all five tables with the Army's published chart (tests/fixtures/aft-score-tables-250601.txt, effective 1 June 2025), and the goal planner's reverse lookup. They never call the backend, and one test checks that scoring makes no network request.

How the scoring works

Official AFT scoring is a set of lookup charts by age bracket and sex or combat-MOS standard. The charts are stored as arrays under components/Calculator/AFTScores/. The scripts in pythonBuilderFiles/ turn charts pasted from the official tables into those arrays, so the data can be regenerated when the Army changes the standards.

Percentiles

Once the five events are entered, the calculator ranks the score against other users' saved results. components/Calculator/PercentileCard.js calls the API's public GET /api/acft_scores/percentiles/ as you type, so it works without an account. Requests are debounced (400 ms), abort after 8 seconds, and a newer request supersedes an older one that is still in flight. You choose what to compare against: age bracket, scoring standard (the "male or combat MOS" toggle) and combat MOS; the choice is remembered on the device.

The server only returns a percentile when the comparison group has at least 20 people, so a narrow grouping cannot single anyone out; below that the card says "Not enough data yet". Each user counts once per group, using their latest result. If the request fails or times out, the card says so and the calculator keeps working.

Over-the-air updates

The app uses expo-updates (EAS Update) so a fix to the scoring tables or the app's JavaScript can reach phones without a store release. On launch it checks for an update in the background, downloads it, and applies it the next time the app starts; it never reloads mid-calculation, and with no signal it just uses the code it already has.

• Channels: builds made with the production, preview and development profiles in eas.json listen to the channel of the same name, so a preview build never receives a production update.
• Runtime version: the appVersion policy (app.json), so an update only reaches builds of the same app version. Anything that needs new native code (an SDK or native-module change) is a new version and a normal store release.
• Only builds that contain expo-updates receive updates. Builds from before it was added keep working but never update this way.
• tests/updatesConfig.test.js fails if this configuration is removed or the channels are mixed up.
• Publishing is npm run update:preview (any clean branch, for a preview build) and npm run update:production (main only, exactly what is merged); both run the tests, lint and bundle check first. Rollback and the full steps are in docs/RELEASING.md.

Design decisions

• Lookup tables, not formulas. Scores are read from the official charts rather than approximated, so results match the published tables.
• Chart generation scripts. Keeping the Python builders in the repo makes updating the tables a repeatable paste-and-run step.
• Offline-first calculators. Scoring runs on the device; the server is only used for accounts, saved results and percentiles, so a slow or unreachable server never blocks scoring.

Limitations

• Standards are correct only as of the date shown in the app and must be updated by hand.
• The tables are checked against the Army chart effective 1 June 2025. When the Army publishes a new scale, add its figures as a new fixture, regenerate the tables, and point tests/aftOfficialTables.test.js at it.

License

MIT. See LICENSE.