Comparison

Weight Diary vs Slim

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

Head to head
About

Weight Diary

Track your weight loss journey with a clear trend line to visualize progress. Log daily weights, estimate loss rates, and plan for your goals. Supports custom start dates and integrates with health platforms.

Highlights
  • Daily weight logging
  • Clear trend line visualization
  • Progress and goal tracking
  • Custom start date setting
  • Apple Health and scale sync
  • BMI and calorie calculators
  • Data backup and export
Read full description

Understand your weight trends over time. Weight Diary helps you cut through daily fluctuations with a clear trend line, so you can quickly see whether you’re moving toward your goal. Log your weight each day to track your progress, estimate your rate of weight loss, and see how long it may take to reach your target. Starting a new diet or routine? Choose a custom start date to measure progress from any point that matters to you. With powerful graphs, goal planning tools, Apple Health support, and Withings/Fitbit scale sync, Weight Diary gives you a simple and effective way to stay on track. Main Features: • See your weight, progress, and goal remaining at a glance • Choose a custom start date for a new diet or milestone • Follow your daily weights with a clear trend line • Switch between the graph, summary, or full weight log with a single tap • Explore your progress over months or years in the full-screen graph • Record body fat % and add custom notes • Plan ahead with goal and calorie calculators • View your BMI with a clear visual display • Comprehensive unit support for pounds, kilograms, and stones • Sync with Apple Health and Withings/FitBit scales • Full data backup, import, and export

About

Slim

Track your weight and BMI with a beautiful interface. Set goals, receive reminders, and unlock rewards on your journey to a healthier you. Seamlessly syncs with Apple Health for easy data import.

Highlights
  • Track weight and BMI
  • Set target weight goals
  • Recurring reminders
  • Unlock rewards
  • Apple Health integration
  • Touch ID/Passcode protection
Features
Read full description

Slim helps you keep a healthy weight. Its wrapped in a beautiful design and makes keeping track of your weight and reaching your weight loss goals a cinch. In today’s times, maintaining a healthy weight (i.e. BMI 19 to 25) is hard, but it’s a crucial part to staying healthy. Weight loss research has shown that losing weight has many positive effects: You will feel more energized, sleep better, improve your immune system, lower your blood pressure and even increase your sex drive. Slim helps you on your journey to reach and keep your desired weight. It can remind you of stepping onto the scale, lets you set a target weight and motivates you through rewards you can unlock. Slim is fully integrated into Apple Health. This means that Slim can import all weight data from other apps and from peripheral devices such as WiFi scales (e.g. Withings WiScale) which integrate Apple Health. So, if you're already using another weight tracker with Apple Health integration, switching is easy since all data will be directly imported to Slim. Most important Features: - Enjoy a stunning user interface - Log and track your weight and BMI - Set and reach your target weight - Set a recurring reminder - Unlock rewards - Sync all data with Apple Health - Lock access to Slim using Touch ID ### If you’re serious about losing weight, Slim Adfree and Slim Pro is for you. Slim Pro includes: - Unlimited charts - Reminders - data export - passcode protection - & all future updates ### The Slim app is free to download. Slim Adfree and Slim Pro requires In-App subscription at $2.99/year or $4.99/year Upgrading to Slim Adfree or Slim Pro will charge your iTunes account. Your subscription automatically renews unless canceled at least 24 hours prior to the end of the current period. Your subscription can be managed in your Account Settings in the App Store settings after purchase. By subscribing to Slim Adfree or Slim Pro you access our terms of use: www.caloon.co/legal/ ---- Icons used in the App Store screenshots taken from: https://icons8.com/ By downloading this app you agree to our Terms of Service and Privacy Policy: www.caloon.co/legal

Screenshots

Weight Diary4 screens
Slim4 screens

Verdict

The call

The clearest difference is review sentiment: Weight Diary at 97% against Slim's 45%. Weight Diary also leads on rating (4.9 vs 4.1) and in-app purchases (none vs 8). Slim's advantage is price (Free vs $7.99) and update cadence (every 3 weeks vs every 6 months). On 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

Slim is free to download; Weight Diary costs $7.99 up front. Slim sells 8 in-app purchases, starting at $1.99 per month. Weight Diary asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Weight Diary holds the better App Store score, 4.9 against 4.1. That said, the two scores are not equally well evidenced: Weight Diary has 2.6K ratings behind it against 74, so its average is the more settled of the two. Written reviews point the same way: 97% of Weight Diary's written reviews are positive against 45% of Slim's.

UpkeepUpdate frequency

Weight Diary ships an update every 6 months, Slim every 3 weeks. Both last shipped on October 29, 2026.

Scorecard10 real differences · 1 level
Weight Diary versus Slim: the parameters behind the verdict, then further details
ParameterWeight DiarySlim
Price$7.99Free — better
Rating4.9 (2.6K ratings) — better4.1 (74 ratings)
Positive reviews96.7% of reviews — better44.9% of reviews
Number of ratings2.6K — better74
Update frequencyEvery 6 monthsEvery 3 weeks — better
AdsNo — betterYes
In-app purchasesNo — betterYes
MonetizationFree — betterFree with in-app purchases
Best chart rank#79 — better—
DevicesiPhone, iPadiPhone, iPad, iPod — better
Requires iOS26.011.0 — better
Further details — not scored
Size11 MB24 MB
Age rating4+12+
DeveloperCURLYBRACE APPS LTD2Hearts IT-Solutions

Customer experience

Weight Diary

All ratings2,628 ratings
Positive98.2%
Neutral1.1%
Negative0.7%
Written reviews983 reviews
Positive96.7%
Neutral1.5%
Negative1.7%

Slim

All ratings72 ratings
Positive72.2%
Neutral9.7%
Negative18.1%
Written reviews89 reviews
Positive44.9%
Neutral13.5%
Negative41.6%

In-app purchases

None

Weight Diary

No in-app purchases

8 purchases

Slim

Subscriptions4
  • Slim Pro - Monthly$1.991 Month
  • Slim Adfree (Year)$2.991 Year
  • Slim Pro$4.491 Year
Show 1 more
  • Slim Pro - Annual$13.991 Year
One-time4
  • Permanently Remove Ads$1.99
  • Slim Pro Pack$3.99
  • Slim Pro$8.99
Show 1 more
  • Slim Pro - Lifetime$19.99

Questions

Is Weight Diary free?
Weight Diary costs $7.99, with no in-app purchases.
Is Slim free?
Slim is free to download, with in-app purchases available.
Which has better reviews, Weight Diary or Slim?
Weight Diary is rated higher. Weight Diary averages 4.9 out of 5 from 2.6K ratings, while Slim averages 4.1 from 74 ratings.
Do Weight Diary or Slim have ads?
Slim shows ads; Weight Diary does not.
Which is updated more often, Weight Diary or Slim?
Weight Diary ships an update every 6 months, and Slim every 3 weeks. Most recently, Weight Diary was updated on October 29, 2026 and Slim on October 29, 2026.

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