Comparison

Fartlek Interval Trainer vs Sun Ring

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Fartlek Interval Trainer

This running app automatically detects spontaneous intervals during Fartlek runs, providing live color-coded feedback on your effort. It also functions as a powerful timer for structured workouts like HIIT and Tabata, offering detailed metrics and syncing with Strava and Apple Health.

Highlights
  • Auto-detection of Fartlek intervals
  • Live color-coded effort feedback
  • Structured workout timer (HIIT, Tabata)
  • Detailed interval metrics
  • Strava and Apple Health integration
  • Advanced effort level detection
Features
Read full description

Build the interval workout you want. Stay on target while you train. Then learn from every session. FiT is an interval timer and training companion for runners on Apple Watch and iPhone. Create classic intervals, HIIT and Tabata workouts—or run freely with automatic Fartlek interval detection. CREATE WORKOUTS YOUR WAY Build simple work-and-rest sessions or advanced workouts with warm-ups, cooldowns, repeated sets and multiple effort levels. FiT makes even complex sessions clear and easy to follow. STAY ON TARGET Color-coded feedback shows whether you’re on pace. Spoken coaching, audio and haptic alerts help you respond without constantly checking your device—and spoken cues automatically match your chosen language. The Dual Progress Ring shows both your current interval and your overall workout progress at a glance. FARTLEK WITHOUT THE BUTTONS Switch to Fartlek mode and run by feel. FiT detects changes in your speed and automatically converts them into recorded intervals. No reaching for your device. No tapping between efforts. Just run. LEARN FROM EVERY WORKOUT See how each interval performed with detailed pace, heart rate, cadence and distance metrics. Compare workouts to understand how your performance changes over time. Personalized coaching insights use your workout data to highlight meaningful patterns and offer practical recommendations for future sessions. ADVANCED EFFORT TRACKING Advanced workouts can distinguish between sprint, hard, moderate and easy efforts, helping you create more varied sessions and analyze every effort afterwards. APPLE WATCH, IPHONE AND YOUR FITNESS APPS Train in your chosen language on Apple Watch or iPhone. Create and edit interval workouts directly on your watch, with controls for inserting, reordering and deleting interval groups. Save completed workouts to Apple Health and sync your sessions with Strava. KEY FEATURES • Flexible interval timer for running, HIIT and Tabata • Automatic Fartlek interval detection • Dual-ring live workout progress • Color-coded pace and effort feedback • Localized spoken coaching, plus audio and haptic alerts • Create and edit interval workouts on Apple Watch • Detailed pace, heart rate, cadence and distance metrics • Performance tracking for every interval • Workout comparisons and personalized insights • Sprint, hard, moderate and easy effort levels • Apple Health and Strava integration • Light and dark appearance Run free. Train smart. Learn from every session. SUBSCRIPTION TERMS FiT offers an optional auto-renewable subscription. Payment will be charged to your Apple ID account at confirmation of purchase. The subscription automatically renews unless auto-renew is turned off at least 24 hours before the end of the current period. You can manage or cancel your subscription at any time in your Apple ID account settings. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://www.iubenda.com/privacy-policy/39192677

About

Sun Ring

This app encourages daily sun exposure by using a familiar ring-closing mechanic. Users can customize their daily goals and track progress with watch face complications and notifications. Review historical data to maintain streaks and stay motivated to enjoy the outdoors.

Highlights
  • Gamified daily sun exposure tracking
  • Customizable daily sun exposure goals
  • Adjustable 'direct sunlight' lux value
  • Watch face widgets and complications
  • Goal completion notifications
  • Daily progress history and streak tracking
Read full description

Sun Ring gamifies daily sun exposure in a format Apple Watch owners will find very familiar: closing a ring. Easily glance at your progress for the day and motivate yourself to go outside to reach your goal. CUSTOMIZABLE THRESHOLDS Set how many minutes you'd like to be in the sun each day, and motivate yourself to enjoy the outdoors. Change what Sun Ring considers as "direct sunlight" by adjusting the minimum lux value your Apple Watch counts towards your goal. WIDGETS/COMPLICATIONS Easily view and keep track of your daily progress right from your watch face. Watch your Sun Ring close throughout the day and inch closer toward your goal. NOTIFICATIONS Never miss out on reaching your goal by turning on Goal Completion notifications. Your Apple Watch will send you a celebratory notification when you have reached or surpassed your daily sun exposure goal. HISTORY Remain motivated by looking at the progress you've made over the past few days and keep your streak alive! Easily see which days you fell short or exceeded your goal and closed your ring. https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

Screenshots

Fartlek Interval Trainer4 screens

Verdict

The call

The clearest difference is in-app purchases: Sun Ring at none against Fartlek Interval Trainer's 4. Sun Ring also leads on iOS requirement (17.0 vs 26.0). On price, ads and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Fartlek Interval Trainer sells 4 in-app purchases, starting at $0.99 per month. Sun Ring asks for nothing beyond the download.

Scorecard3 real differences · 7 level
Fartlek Interval Trainer versus Sun Ring: the parameters behind the verdict, then further details
ParameterFartlek Interval TrainerSun Ring
PriceFreeFree
Rating—5.0 (1 ratings) — better
Positive reviews75.0% of reviews—
Number of ratings—1 — better
Update frequencyEvery 9 days—
AdsNoNo
In-app purchasesYesNo — better
MonetizationFreemiumFree — better
DevicesiPhone, Apple WatchiPhone, Apple Watch
Requires iOS26.017.0 — better
Further details — not scored
Size86 MB2 MB
Age rating4+4+
DeveloperRichard EnglishAaron Taylor

Customer experience

Fartlek Interval Trainer

Written reviews4 reviews
Positive75.0%
Neutral0.0%
Negative25.0%

Sun Ring

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

4 purchases

Fartlek Interval Trainer

Subscriptions2
  • Monthly$0.991 Month
  • Annual7 Days trial$6.991 Year
One-time2
  • RemoveAds$0.99
  • Lifetime$14.99
None

Sun Ring

No in-app purchases

Questions

Is Fartlek Interval Trainer free?
Fartlek Interval Trainer is free to download, with in-app purchases available.
Is Sun Ring free?
Sun Ring is free to download, with no in-app purchases.
Do Fartlek Interval Trainer or Sun Ring have ads?
Neither Fartlek Interval Trainer nor Sun Ring shows ads.

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