Comparison

1RM Calculator vs CK Strength

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

Head to head
About

1RM Calculator

Easily calculate your one-rep max (1RM) strength with this app. It supports RPE input and allows you to estimate rep maxes based on your 1RM. Track your progress by saving your 1RM history for different exercises.

Highlights
  • 1RM calculation with RPE
  • Rep max estimation
  • Save 1RM history
  • Customizable exercises
  • Dark theme
Features
Read full description

Estimate your one rep max (1RM) from any set. Enter the weight and reps you lifted, add RPE if you track it, and get your estimated max in seconds. FEATURES - 1RM calculator with optional RPE: reps left in the tank are counted, so 10 reps at RPE 7 is treated like a 13-rep max - Transparent formulas: your estimate is the average of Epley, Brzycki (up to 12 reps), Wathan, and Mayhew - Estimated rep maxes from 2 to 12 reps, each shown as a percentage of your 1RM, for planning working sets - Save results to your history by exercise, including your own custom exercises - Edit or backdate saved records - Export your history as CSV - kg or lbs, light or dark theme - 9 languages - No account needed: your records stay on your device PRO - 1RM progress chart for each exercise - Rep max table with your best recorded set for each rep count - No ads Pro is available as a monthly or yearly subscription, or as a one-time lifetime purchase. Subscriptions renew automatically until canceled in your store account settings. Your 1RM is an estimate, not a tested max. Estimates are most reliable at lower reps. Terms: https://1rm.workoutwise.app/legal/terms/ Privacy Policy: https://1rm.workoutwise.app/legal/privacy-policy/

About

CK Strength

Features
Read full description

CK Strength + Performance Strategies Virtual Group Coaching: Follow along with group Training programs: 2, 3, or 4x per week -Progression updates every 5 weeks - Weekly Check In - Online Forum access, weekly Q+A - Exercise Library - Exclusive Tips and content for subscribers Template Training Programs: Find the program to fit your goals: Hypertrophy, Strength, Powerlifting, Sport Performance - 5 or 6 week Template Programs for 3, 4, or 5x per week frequency Custom Ongoing Coaching: Trust Christian Kruszewski as your coach to help you reach your Strength, Hypertrophy, Fat Loss, Powerlifting, or Sport Performance goals! Includes: - Custom programming (Updated as you complete your training) -- Monthly Virtual Check in (Call or Video Chat) - Weekly Email Check In - Video submissions for form review on your lifts and exercises - Nutrition coaching and guidance * App access requires paid coaching plan Terms of use: https://kahunas.io/terms-conditions Privacy policy: https://kahunas.io/privacy

Screenshots

1RM Calculator4 screens
CK Strength3 screens

Verdict

The call

The clearest difference is update cadence: CK Strength at every 6 weeks against 1RM Calculator's every 4 months. On price, ads, in-app purchases 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. 1RM Calculator sells 3 in-app purchases, starting at $1.99 per month and CK Strength sells 1 in-app purchase, starting at $219.00 per month. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

1RM Calculator ships an update every 4 months, CK Strength every 6 weeks. The most recent releases landed on October 30, 2026 and October 25, 2026 respectively.

Scorecard1 real difference · 9 level
1RM Calculator versus CK Strength: the parameters behind the verdict, then further details
Parameter1RM CalculatorCK Strength
PriceFreeFree
Rating4.9 (128 ratings) — better—
Positive reviews100.0% of reviews—
Number of ratings128 — better—
Update frequencyEvery 4 monthsEvery 6 weeks — better
AdsNoNo
In-app purchasesYesYes
MonetizationFree with in-app purchases—
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.015.0
Further details — not scored
Size28 MB50 MB
Age rating4+17+
DeveloperYuri KoshiishiCK Strength + Performance Strategies LLC

In-app purchases

3 purchases

1RM Calculator

Subscriptions2
  • 1 Rep Max Pro Monthly$1.991 Month
  • 1 Rep Max Pro Annual$9.991 Year
One-time1
  • 1 Rep Max Pro Lifetime$29.99
1 purchases

CK Strength

Subscriptions1
  • Custom Ongoing Coaching$219.001 Month

Questions

Is 1RM Calculator free?
1RM Calculator is free to download, with in-app purchases available.
Is CK Strength free?
CK Strength is free to download, with in-app purchases available.
Do 1RM Calculator or CK Strength have ads?
Neither 1RM Calculator nor CK Strength shows ads.
Which is updated more often, 1RM Calculator or CK Strength?
1RM Calculator ships an update every 4 months, and CK Strength every 6 weeks. Most recently, 1RM Calculator was updated on October 30, 2026 and CK Strength on October 25, 2026.

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