Comparison

ONE vs Arc

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

Head to head
About

ONE

This app simplifies intermittent fasting with a one-tap timer and progress tracker. It guides users through fasting stages, offers various plans, and provides insights into body changes. The focus is on building consistent habits without unnecessary complexity.

Highlights
  • One-tap fasting timer
  • Live fasting stage tracking
  • Multiple fasting plan options
  • Daily streak tracking
  • Weight and water tracking
  • AI-powered progress summaries
  • Offline functionality
Features
Read full description

Fasting made simple. Start a fast in one tap, watch your body move through each stage, and build the streak that actually changes things. ONE is an intermittent fasting tracker for people who want the habit, not the homework. No account. No clutter. Just the timer, the stages, and your progress. CHOOSE YOUR PLAN • 12:12, 14:10, 16:8, 18:6, 20:4 and OMAD (23:1) • Flexi mode for open-ended fasts • A difficulty rating on every plan, so you pick one you'll actually keep • Custom Timer for any length you like — free, no upgrade • Change plan any time. Nothing is locked in. WATCH WHAT'S HAPPENING • Live fasting stages: blood sugar falling, fat burning, ketosis, autophagy • Know exactly when the next stage arrives • Plain-language explanation of what your body is doing, and why STAY ON TRACK • Reminders when your fast starts and ends • A notification as you reach each new stage • Fix your start or end time when life happens • Daily streaks that reward consistency, not perfection • Apple Health: your fasts written out, your weight read in — free SEE YOUR PROGRESS • Every fast logged automatically, nothing to fill in • Your recent fasts, free forever WHAT ONE PREMIUM ADDS • Your full fasting history, not just the last few • AI Coach — weekly and monthly written analysis of how you actually fast, what changed, and what to try next • Trends: streak calendar, fasting-hours charts and weight trend • Protein tracker, with a daily target set from your weight • Water tracking against a goal, right on the timer • Your own Quick Start lengths, tuned to the fasts you really do • Apple Watch app with complications — start and end a fast from your wrist • Home Screen widget and a Live Activity on your Lock Screen The timer, every plan, the stages and the Custom Timer are free. Forever. BUILT TO STAY OUT OF THE WAY • Start fasting in under a minute — no sign-up, no email • Optional account, so your history follows you to a new phone SUBSCRIPTION ONE Premium is an auto-renewing subscription, available monthly or annually. Payment is charged to your Apple Account at confirmation of purchase. It renews automatically unless cancelled at least 24 hours before the end of the current period, and your account is charged for renewal within 24 hours of the end of that period. Manage or cancel any time in your Apple Account settings. Medical disclaimer: ONE is for general wellness only and does not provide medical advice. Talk to a qualified healthcare professional before starting any fasting programme, particularly if you are pregnant, breastfeeding, diabetic, under 18, or have a history of disordered eating. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://www.fastingtime.co/privacy

About

Arc

Features
Read full description

The AI coach that lives on your iPhone and Watch — not in someone's cloud. Now on iPhone Duo Arc builds you a real training plan across the sports you actually do — running, cycling, walking, swimming, and strength — then adapts it week to week based on how your body is responding. Unlike coaching apps that ship your data off to a server, Arc's AI coach runs privately on your device: offline, fast, and yours. Train the way you actually train Mix running, cycling, walking, swimming, and strength in one plan. Add or drop activities anytime and Arc folds them into your current block — no starting over. Meet your coach — now on your wrist Ask Arc anything: get a pre-session briefing, ask why today is easy, or check whether you're on track for your event — right from your Apple Watch. Answers are handled privately through Apple's on-device and Private Cloud Compute models. Show it a photo, too: snap a race elevation sign, a gym whiteboard, or a screenshot from another app, and Arc reads it and answers. A plan that adapts — and explains itself Arc watches your readiness, your training load, and how each session actually went, then adjusts the days ahead. Every suggestion comes with a "Why this?" breakdown showing the exact signals it weighed and which way each one pushed — no black box. Because life happens Injured, sick, traveling, or just need a break? Tell Arc from the Today screen and it reshapes your plan for you. Days off count as rest, not missed — and your event date never moves. When you're ready, ask Arc how to ease back in. Training built around your body • Cycle-aware readiness — if you track your cycle in Apple Health, Arc factors your phase into readiness and your weekly plan (read-only; nothing is ever written back). • Daily check-ins — muscle soreness, chafing, and saddle soreness feed your readiness score, so run and ride niggles both count. • Readiness at a glance — on your Lock Screen, in the Dynamic Island, and on your watch. Serious analytics, made readable See your Performance Management Chart — Fitness, Fatigue, and Form plotted together over time — so you can watch fitness build and freshness peak for your big day. Track your acute-to-chronic load balance in plain English before it turns into an overuse injury. Event day, dialed in Turn your goal time and course into an even-effort pacing plan that eases the climbs and lets you run — or ride — the descents. Arc even tells you whether your current fitness is on track for the goal. Got more than one event? Add your tune-up B and C races and Arc fits them into your build with a light taper and easy day around each. Fits your world • Log by swiping on Today, ask Siri, or tap a Control Center button • Personal records, achievements, and gear-mileage tracking • Pods — share progress and weekly challenges with friends • Fully localized in English and Spanish Arc Pro Free to start. Arc Pro unlocks the AI coach, the Performance Management Chart, event pacing, injury rebuilds, and more. Your AI endurance coach — prescriptive, adaptive, transparent, and private. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://largentlabs.com/arc/privacy.html

Screenshots

ONE4 screens
Arc4 screens

Verdict

The call

The clearest difference is iOS requirement: ONE at 15.1 against Arc's 26.5. On price, update cadence, ads and in-app purchases 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. ONE sells 6 in-app purchases, starting at $2.99 per 7 days and Arc sells 2 in-app purchases, starting at $4.99 per month. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

ONE ships an update every 4 weeks, Arc monthly. The most recent releases landed on October 24, 2026 and October 25, 2026 respectively.

Scorecard1 real difference · 9 level
ONE versus Arc: the parameters behind the verdict, then further details
ParameterONEArc
PriceFreeFree
Rating5.0 (2 ratings) — better—
Positive reviews100.0% of reviews—
Number of ratings2 — better—
Update frequencyEvery 4 weeks — betterMonthly
AdsNoNo
In-app purchasesYesYes
MonetizationFreemium—
DevicesiPhone, iPad, iPod, Apple Watch — betteriPhone, iPad, Apple Watch
Requires iOS15.1 — better26.5
Further details — not scored
Size49 MB11 MB
Age rating17+4+
DeveloperCreate RushLargent Labs, LLC

In-app purchases

6 purchases

ONE

Subscriptions6
  • Standard Weekly$2.997 Days
  • Premium Weekly$4.997 Days
  • Standard Monthly$4.991 Month
Show 3 more
  • Premium Monthly$9.991 Month
  • Standard Yearly$49.991 Year
  • Premium Yearly$99.991 Year
2 purchases

Arc

Subscriptions2
  • Pro Monthly7 Days trial$4.991 Month
  • Pro yearly7 Days trial$39.991 Year

Questions

Is ONE free?
ONE is free to download, with in-app purchases available.
Is Arc free?
Arc is free to download, with in-app purchases available.
Do ONE or Arc have ads?
Neither ONE nor Arc shows ads.
Which is updated more often, ONE or Arc?
ONE ships an update every 4 weeks, and Arc monthly. Most recently, ONE was updated on October 24, 2026 and Arc on October 25, 2026.

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