1RM Calculator vs 531 Strength
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
1RM Calculator
Estimate your maximum weight lifted for a single repetition. Input your successful lifts and reps to gauge strength, compare progress, and plan future training. Offers advanced features for detailed tracking and analysis.
- Estimate 1-rep max
- Track lift history and progress
- Historical chart and list views
- Multiple estimation formulas
- Calculate multiple rep maxes
- Switch between lbs and kgs
- View percentages of 1-rep max
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1RM Calculator is a tool to help you determine your 1-rep max! Because of the nature and stress of attempting a 1-rep max, this utility allows you to enter in a weight you successfully lifted at the number of reps you performed in order to see what your estimated 1-rep max is. This not only helps give you an idea of the weight to attempt when actually performing a 1-rep max but also to gauge your strength and compare different rep schemes performed at different reps. If one week you were able to bench press 190 lbs at 6 reps and the next week you did 200 for 5, this app gives you a way to compare the two as best as possible (190 lbs @ 6 reps gives a 1-rep max estimate of 223 lbs vs. 200 lbs @ 5 reps gives a 1-rep max estimate of 227 lbs) **** PRO VERSION FEATURES **** Upgrade to the Pro version to get all the settings and features! - Ad free experience - Save your lifts and track your history and progress - Historical chart and list views, categorized by exercise - More formulas in order to best estimate your maximums - Multiple rep maxes (up to 10) - Ability to switch between lbs and kgs - Percentage view that shows anywhere from 50% to 125% of your 1-rep max 1RM Calculator is only intended to give estimates based on the data you enter. Since these are calculated values they may vary with actual measured values. Always ensure you have a spotter, and work your way up to your limit with more than adequate warmup to prevent injuries.
531 Strength
This app simplifies tracking your progress on the 5/3/1 strength training program. It calculates and displays weights, reps, and sets based on your one-rep max, allowing you to easily plan and execute your workouts. Rounding options help match available gym plates.
- Calculate 5/3/1 weights
- Track 1RM for exercises
- View cycle step weights
- Round weights to available plates
- Full overview of weights, reps, sets
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Makes it quick and easy to get a full overview of all weights, reps and sets based off your 1RM when you’re following the 5/3/1 program. - Save your current 1 RM for each of the four exercises - View calculated weights for each step in the cycle - Round the weight to match the plates you have available This app is made for people who are familiar with the structure of the 5/3/1 program and who needs simple access to the calculated weights for each exercise.
Screenshots
Verdict
The clearest difference is review sentiment: 531 Strength at 94% against 1RM Calculator's 37%. 531 Strength also leads on rating (4.9 vs 4.5) and ratings volume (12K vs 222). 1RM Calculator's advantage is ads (none vs shown) and update cadence (every 3 weeks vs every 2 months). On price, in-app purchases, monetization model 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
Both are free to download. 1RM Calculator sells 1 one-off in-app purchase and 531 Strength sells 4 one-off in-app purchases. Whichever you choose, the download price is not the number that matters.
531 Strength holds the better App Store score, 4.9 against 4.5. That said, the two scores are not equally well evidenced: 531 Strength has 12K ratings behind it against 222, so its average is the more settled of the two. Written reviews point the same way: 37% of 1RM Calculator's written reviews are positive against 94% of 531 Strength's.
1RM Calculator ships an update every 3 weeks, 531 Strength every 2 months. The most recent releases landed on October 23, 2026 and November 1, 2026 respectively.
| Parameter | 1RM Calculator | 531 Strength |
|---|---|---|
| Price | Free | Free |
| Rating | 4.5 (222 ratings) | 4.9 (12K ratings) — better |
| Positive reviews | 36.8% of reviews | 94.0% of reviews — better |
| Number of ratings | 222 | 12K — better |
| Update frequency | Every 3 weeks — better | Every 2 months |
| Ads | No — better | Yes |
| In-app purchases | Yes | Yes |
| Monetization | Free with in-app purchases | Free with in-app purchases |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 12.1 — better | 18.0 |
| Further details — not scored | ||
| Size | 20 MB | 26 MB |
| Age rating | 4+ | 4+ |
| Developer | David Bai | Henrik Jachobsen |
Customer experience
1RM Calculator
531 Strength
User reviews
1RM Calculator
From 222 App Store ratingsWhat we love
- 👍 Simple and easy to use
- 🚀 Calculates 1 rep max quickly
- 💡 Helps figure out percentages
- 👍 Good for tracking routines
- 👍 Clean design
Room to improve
- 🐛 Pro version not working
- 🐛 Paid features inaccessible
- 🐛 App crashes after upgrade
- 🐛 UI needs improvement
- 🐛 Missing features
531 Strength
From 12K App Store ratingsWhat we love
- 🚀 Simple and efficient
- 👍 Intuitive interface
- 💪 Helps with strength gains
- 🔧 Customizable features
- ⏱️ Convenient timer
Room to improve
- 🔢 Inaccurate percentage calculations
- 🗓️ Lack of ability to plan future workouts
- 📋 Limited exercise tracking
- 💰 Paid features not worth the cost
Bugs and requests
1RM Calculator
Reported bugs
8 issues- Pro not working after purchase
- Paid upgrade not granting access
- App crashes after upgrade
- Feedback email link broken
- + button crashes app
Show 3 moreShow fewer
- UI truncated for percentages view
- Cannot use three-digit weight numbers
- App crashes after upgrade
Requested features
7 requests- Ability to re-arrange exercises
- Ability to re-name exercises
- Ability to delete exercises
- See all trend lines on one graph
- Track more than one set per day
Show 2 moreShow fewer
- Allow decimals in weight input
- Dark mode
531 Strength
Reported bugs
2 issues- Rest timer stops when app is backgrounded
- Plate calculator not flexible enough
Requested features
4 requests- Ability to adjust training max separately from 1RM
- Option to track rep PRs and estimated 1RM
- Accessory exercise tracking and planning
- Sync progress across devices
In-app purchases
1RM Calculator
- Pro Upgrade$1.99
531 Strength
- Additional exercises$1.99
- Adjustable set$1.99
- Plate calculator$1.99
Show 1 moreShow fewer
- Progress log$6.99
Questions
Is 1RM Calculator free?
Is 531 Strength free?
Which has better reviews, 1RM Calculator or 531 Strength?
Do 1RM Calculator or 531 Strength have ads?
Which is updated more often, 1RM Calculator or 531 Strength?
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