Comparison

CalmTide vs Isla

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

Head to head
About

CalmTide

Features
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Lower your baseline cortisol. CalmTide reads the Apple Health data you already have — sleep, HRV, workouts, resting heart rate, mindful minutes — and turns it into one clear picture of your stress biology: an HPA Balance Score today, and an estimated baseline-cortisol trend over 8 weeks. Not another meditation timer. A measurement layer for calm. Everything runs on your device. No account, no cloud, no analytics. Your health data never leaves your phone. SEE TODAY CLEARLY • HPA Balance Score (0–100) from a named, citation-backed model — tap any number to see the research behind it • One smart recommendation, chosen for today — not a generic list • A daily protocol checklist: breathwork, Zone 2, sleep, morning light • Recovery signals at a glance: HRV, resting heart rate, sleep, respiratory rate • Where your HRV and resting heart rate sit against typical ranges for your age and sex (Pro) FIND YOUR PATTERNS • Morning-after insights: what caffeine, alcohol, late meals and hard workouts did to your HRV, sleep and readiness — read the next morning, when the biology actually lands • What your check-ins reveal (Pro): whether how you feel actually tracks your sleep, HRV and training, compared across your own days • Your strongest cortisol link, from your own data — suggestive, not causal, and always explained • Personal records: longest streak, best HPA week, calmest morning UNDERSTAND YOUR WEEK • A weekly retrospective that ranks exactly what moved your score — sleep, morning light, HRV, mindfulness, training load — in points, this week versus last • Every workout with heart-rate data scored for its cortisol effect: reducing, neutral, or spiking. Sessions without it still count toward your weekly dose — they are never guessed at • Training load as plain figures: acute-to-chronic ratio, monotony and strain (Pro) ACT ON IT • Practice hub: cyclic sighing (Balban 2023) and resonance breathing (Steffen 2020), in 2, 5 or 10-minute doses, suggested by situation — evening wind-down, post-workout, elevated load • Completed sessions save to Apple Health as Mindful Minutes • Morning-light coaching to anchor your body clock — the clock that times your morning cortisol rise • Smart, quiet notifications that arrive when they help — never to interrupt WATCH YOUR BASELINE FALL • An 8-week estimated baseline-cortisol trend with your life events pinned to it — illness, travel, deadlines — so shifts make sense • A 7-day cortisol forecast from your training and sleep (Pro) • Check in from your wrist with the Apple Watch app PRIVATE BY DESIGN • On-device analysis, including the optional Calm Coach explainer • Export or restore your data any time — it's yours • App Privacy label: Data Not Collected CalmTide is free to use daily. CalmTide Pro (full 8-week trend, extended 60- and 90-day history, the cortisol forecast, score & forecast widgets, scores on Apple Watch, advanced training-load analytics and Calm Coach) is available as a monthly or annual subscription, or a one-time lifetime purchase. New subscribers get a 1-month free trial. Subscriptions auto-renew until cancelled; the price and any trial are shown before you confirm. CalmTide is a wellness tool. It estimates — it does not measure cortisol, and it does not diagnose or treat any medical condition.

About

Isla

Read full description

Isla is your island of calm — a gentle, private way to settle your nervous system in about three minutes, whenever life feels like too much. No long courses. No streaks to keep. No pressure. Just tell Isla how you feel right now — wired, anxious, frozen, overstimulated, restless, or like you can't sleep — and it matches you to a short, body-based practice for this exact moment. HOW IT WORKS • Check in with how you feel, right now • Follow a calm ~3-minute somatic or breathing practice, guided by a soft voice and a breathing orb • Afterwards, notice how you feel — and let Isla quietly learn what helps you PERSONALIZED, PRIVATELY Isla uses on-device intelligence to choose the right practice and frame it warmly for you — entirely on your iPhone. Nothing you share leaves your device. There are no accounts and no third-party tracking, and your reflections are created privately on your iPhone. You can clear everything anytime. MADE TO FIT YOU Pick a profile that sounds like you — easily overstimulated, a racing mind, running on empty, wired and can't switch off, or simply "show me everything" — and Isla adapts its tone and suggestions. Change it whenever your needs shift. WHAT'S INSIDE • Short somatic, breathing, and grounding practices • A guided player with a gentle voice and a calming breathing orb (choose a Default, Woman, or Man voice) • Browse and start any practice directly • Gentle weekly reflections that notice patterns in how you've felt • An optional daily reminder • Full Dynamic Type, VoiceOver, and Reduce Motion support WORKS OFFLINE The core practices work with no connection and no AI — calm shouldn't depend on a signal. ISLA PREMIUM Unlock the full experience: • Personalized, AI-matched practices • The complete practice library • Private weekly reflections Try Isla Premium free for 7 days, then $4.99/month — or $29.99/year. Prices may vary by region. Isla is for relaxation and general wellbeing. It is not medical advice or a substitute for professional care. If you're struggling, please reach out to a qualified professional. your island of calm. — Subscription details — Isla Premium is an auto-renewable subscription. Monthly ($4.99) includes a 7-day free trial for new subscribers; Yearly is $29.99. Payment is charged to your Apple Account at confirmation of purchase. The subscription renews automatically unless turned off at least 24 hours before the end of the current period; manage or cancel anytime in your Apple Account settings. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://www.pigloboutique.com/#/privacy

Screenshots

CalmTide4 screens
Isla4 screens

Verdict

The call

The clearest difference is device support: CalmTide at 3 against Isla's 1. CalmTide also leads on iOS requirement (18.6 vs 26.0). On price, ads and in-app purchases there is nothing between them.

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

CostPrice Ā· In-app purchases Ā· Ads Ā· Monetization

Both are free to download. CalmTide sells 3 in-app purchases, starting at $4.99 per month and Isla sells 2 in-app purchases, starting at $4.99 per month. Whichever you choose, the download price is not the number that matters.

Scorecard2 real differences Ā· 4 level
CalmTide versus Isla: the parameters behind the verdict, then further details
ParameterCalmTideIsla
PriceFreeFree
Update frequencyEvery 10 days—
AdsNoNo
In-app purchasesYesYes
DevicesiPhone, iPad, Apple Watch — betteriPhone
Requires iOS18.6 — better26.0
Further details — not scored
Size9 MB2 MB
Age rating12+4+
DeveloperMichael SmithMarkus Vaha

In-app purchases

3 purchases

CalmTide

Subscriptions2
  • Monthly$4.991 Month
  • Annual1 Month trial$29.991 Year
One-time1
  • Lifetime$59.99
2 purchases

Isla

Subscriptions2
  • Isla Premium — Monthly$4.991 Month
  • Isla Premium — Yearly$29.991 Year

Questions

Is CalmTide free?
CalmTide is free to download, with in-app purchases available.
Is Isla free?
Isla is free to download, with in-app purchases available.
Do CalmTide or Isla have ads?
Neither CalmTide nor Isla shows ads.

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