Comparison

Correlate vs CalmTide

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

Head to head
About

Correlate

Features
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Track habits, mood, health, and daily patterns in one private journal. Define your own trackers: sleep, mood, coffee, symptoms, exercise, medication, productivity, or anything else. Log each day with a tap, then explore your history with charts, notes, search, and PDF reports. Because every tracker is customizable, Correlate works equally well as a habit tracker, mood tracker, symptom log, sleep journal, or medication log - adapting to your routine instead of forcing your life into a preset template. Over time, Correlate helps you spot trends, answer questions, and get a clearer view of what has actually been happening in your life. • Create custom trackers with toggles or sliders • Record events the moment they happen; Correlate opens fast enough that it never feels like a chore • Add daily notes for a private journal • Explore your history with interactive charts you can zoom and pan • Search your data to find patterns and trends • Save PDF reports with graphs, tables, and search results • Sync with iCloud or your own WebDAV server Correlate is designed for sensitive personal data. No ads, no tracking, and no external account required.

About

CalmTide

Features
Read full description

CalmTide estimates stress load from your Apple Health data — it does not measure cortisol. See your stress load clearly, and settle it. CalmTide reads the Apple Health data you already have — sleep, HRV, workouts, resting heart rate, mindful minutes — and turns it into one clear picture: an HPA Balance Score today, a weekly balance trend, and a Breathe tab for when you want to settle. SEE TODAY CLEARLY • HPA Balance Score (0–100) from a named model with its sources cited — tap any number to see the research behind it • Today's estimate says how much data backs it, and a signal CalmTide couldn't measure reads "Not measured" — never as a bad day • Pick a focus — less stress, better sleep, avoiding burnout or training without overtraining — and Today and Insights lead with it • Your HRV and resting heart rate against typical ranges for your age and sex, once you confirm your age (Pro) BREATHE • A Breathe tab: cyclic sighing (Balban 2023) and resonance breathing (Shaffer 2020), in 2, 5 or 10-minute sessions, suggested for the moment you're in — free • Follow a session with your eyes closed: a gentle tap at each breath, the screen kept awake for the session only, and a pacer bar instead of the orb when Reduce Motion is on • Your mindful minutes this week from Apple Health, with no target and no streak to keep • More practices (Pro): NSDR / yoga nidra, a short cold finish for the morning, and a post-meal walk — each guided, each naming the study behind it • Sessions save to Apple Health as Mindful Minutes and count down on your Lock Screen FIND YOUR PATTERNS • Morning-after insights: what caffeine, alcohol, late meals and hard workouts did to your HRV, sleep and readiness • A one-time note when CalmTide first spots a pattern in your own check-ins — an association, never a cause • What your check-ins reveal (Pro): whether how you feel tracks your sleep, HRV and training UNDERSTAND YOUR WEEK • A weekly retrospective that ranks what moved your balance — only signals measured in both weeks (Pro) • Workouts with heart-rate data labelled reducing, neutral or spiking for their estimated load. Sessions without it still count toward your weekly dose, never guessed at • Training load as plain figures: acute-to-chronic ratio, monotony and strain (Pro) • Your weekly HPA balance over 8 weeks, with life events pinned to it, and a 7-day forecast of your load estimate (Pro) • An appointment summary: one page and a CSV of what CalmTide measured, and nothing it couldn't (Pro) ON YOUR WATCH FACE • Two complications: CalmTide balance and CalmTide readiness, each showing when it last updated (scores with Pro) • Haptic-paced breathing with your live heart rate, and check-ins that sync to your iPhone • Double Tap starts and finishes a breathing session on Apple Watch Series 9 and later • Ask Siri "What's my cortisol today in CalmTide?" for today's estimated load (Pro), or start a session from Control Center or the Action button PRIVATE BY DESIGN • On-device analysis, including the optional Calm Coach explainer • App Privacy label: Data Not Collected • On iPhone Duo, Breathe and Insights use both pages when open, and sessions adapt to every pose Scores need an Apple Watch, or another app that writes sleep, HRV or resting heart rate to Apple Health. CalmTide is free to use daily. CalmTide Pro unlocks everything marked (Pro), plus 60- and 90-day history, score & forecast widgets and Calm Coach — as a monthly or annual subscription, or a one-time lifetime purchase with no subscription. The annual subscription includes a 1-month free trial for new subscribers. Subscriptions auto-renew until cancelled; the price and any trial are shown before you confirm. CalmTide is a wellness tool. It does not diagnose or treat any medical condition. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://twisteddatastudios.com/calmtide-privacy.html

Screenshots

Correlate4 screens
CalmTide4 screens

Verdict

The call

The clearest difference is price: CalmTide at Free against Correlate's $12.99. Correlate's advantage is in-app purchases (none vs 3) and iOS requirement (16.0 vs 26.0). On update cadence, ads and device support 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

CalmTide is free to download; Correlate costs $12.99 up front. CalmTide sells 3 in-app purchases, starting at $4.99 per month. Correlate asks for nothing beyond the download.

UpkeepUpdate frequency

Both ship on a similar rhythm, roughly every 3 weeks. Both last shipped on October 31, 2026.

Scorecard3 real differences Ā· 3 level
Correlate versus CalmTide: the parameters behind the verdict, then further details
ParameterCorrelateCalmTide
Price$12.99Free — better
Update frequencyEvery 3 weeksEvery 3 weeks
AdsNoNo
In-app purchasesNo — betterYes
DevicesiPhone, iPadiPhone, iPad, Apple Watch — better
Requires iOS16.0 — better26.0
Further details — not scored
Size2 MB10 MB
Age rating4+12+
DeveloperJames Michael BeckMichael Smith

In-app purchases

None

Correlate

No in-app purchases

3 purchases

CalmTide

Subscriptions2
  • Monthly$4.991 Month
  • Annual$29.991 Year
One-time1
  • Lifetime$59.99

Questions

Is Correlate free?
Correlate costs $12.99, with no in-app purchases.
Is CalmTide free?
CalmTide is free to download, with in-app purchases available.
Do Correlate or CalmTide have ads?
Neither Correlate nor CalmTide shows ads.
Which is updated more often, Correlate or CalmTide?
Correlate ships an update every 3 weeks, and CalmTide every 3 weeks. Most recently, Correlate was updated on October 31, 2026 and CalmTide on October 31, 2026.

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