RunCalculator Pro
PublishedRunCalculator Pro is a free web app for runners and walkers. Build a route by clicking on the map — and instantly get distance, elevation profile, calories, steps, pace, and estimated time. It ships with six specialized calculators: pace, race time predictor, splits, treadmill, VO₂max, and calories. Works offline as a PWA, stores routes locally, and exports them to GPX.
/// Key features
- Build a route by clicking on the map, with automatic distance and elevation profile calculation
- Random route generation from a target distance and elevation range
- Real-time calories, steps, pace, and time — adjusted for weight, activity type, and terrain
- Six calculators: pace, race predictor, splits, treadmill, VO₂max (VDOT), calories
- Save favorite routes locally and export them to GPX
- PWA: installs like an app and works offline
- Kilometers and miles, dark and light themes
- Localized into 5 languages: English, Russian, Spanish, Japanese, Chinese
/// Screenshots
About the project
RunCalculator Pro was born from a simple question: "how far will I actually run — and how much will I burn — on this exact route?" Instead of tables and formulas, there's an interactive map: click along the streets and the app calculates distance, elevation gain, calories, steps, and estimated time for you.
It is a fully client-side web app: all calculations run in the browser, routes are stored locally, and once installed as a PWA it keeps working even without internet.
Key features
Route planner on the map
The main screen is a dark Leaflet map on top of OpenStreetMap:
- Click on the map — points connect into a route, and markers can be dragged
- Elevation profile with total gain and loss along the route
- Live metrics panel: distance, time, calories, steps, average pace
- Share a route with a link
Route generator
Not sure where to run? Set a target distance and elevation range — the app generates a random loop starting from your location.
Six calculators for runners
- Pace calculator — pace, speed, and time for any distance
- Race predictor — estimated 5K, 10K, half, and marathon times from a recent race
- Splits calculator — per-kilometer breakdown for a goal time
- Treadmill calculator — pace conversion accounting for belt incline
- VO₂max (VDOT) — maximal oxygen uptake estimate, including the Cooper test
- Calorie calculator — energy burn based on weight and activity type
My routes and export
Save routes to a local library and export them to GPX — the file opens in Garmin, Strava, and any running app.
Technical highlights
Fully client-side
No backend: calculations, route storage, and settings live in the browser. That means both privacy and instant feedback.
PWA with offline mode
A service worker caches the app: after the first visit the calculators work without a network, and the site installs to the home screen like a regular app.
Stack
Next.js (App Router) + TypeScript, maps on Leaflet and react-leaflet over OpenStreetMap, state in Zustand, validation with Zod, styling with Tailwind CSS, animations with Framer Motion, i18n via next-intl with five locales.
Privacy
The app requires no sign-up and collects no personal data: routes and settings are stored only in your browser.
Status
The app is live and free at runcalculator.pro.
