Comparison

1RM Calculator vs 531 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

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.

Highlights
  • 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
Features
Read full description

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.

About

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.

Highlights
  • Calculate 5/3/1 weights
  • Track 1RM for exercises
  • View cycle step weights
  • Round weights to available plates
  • Full overview of weights, reps, sets
Features
Read full description

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

1RM Calculator4 screens
531 Strength4 screens

Verdict

The call

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

CostPrice · In-app purchases · Ads · Monetization

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.

ReceptionRating · Positive reviews · Number of ratings

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.

UpkeepUpdate frequency

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.

Scorecard6 real differences · 4 level
1RM Calculator versus 531 Strength: the parameters behind the verdict, then further details
Parameter1RM Calculator531 Strength
PriceFreeFree
Rating4.5 (222 ratings)4.9 (12K ratings) — better
Positive reviews36.8% of reviews94.0% of reviews — better
Number of ratings22212K — better
Update frequencyEvery 3 weeks — betterEvery 2 months
AdsNo — betterYes
In-app purchasesYesYes
MonetizationFree with in-app purchasesFree with in-app purchases
DevicesiPhone, iPad, iPod — betteriPhone, iPad
Requires iOS12.1 — better18.0
Further details — not scored
Size20 MB26 MB
Age rating4+4+
DeveloperDavid BaiHenrik Jachobsen

Customer experience

1RM Calculator

All ratings222 ratings
Positive88.7%
Neutral2.3%
Negative9.0%
Written reviews38 reviews
Positive36.8%
Neutral10.5%
Negative52.6%

531 Strength

All ratings11,645 ratings
Positive98.0%
Neutral1.2%
Negative0.8%
Written reviews282 reviews
Positive94.0%
Neutral2.8%
Negative3.2%

User reviews

1RM Calculator

From 222 App Store ratings

What 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 ratings

What 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 more
  • 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 more
  • 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

1 purchases

1RM Calculator

One-time1
  • Pro Upgrade$1.99
4 purchases

531 Strength

One-time4
  • Additional exercises$1.99
  • Adjustable set$1.99
  • Plate calculator$1.99
Show 1 more
  • Progress log$6.99

Questions

Is 1RM Calculator free?
1RM Calculator is free to download, with in-app purchases available.
Is 531 Strength free?
531 Strength is free to download, with in-app purchases available.
Which has better reviews, 1RM Calculator or 531 Strength?
531 Strength is rated higher. 1RM Calculator averages 4.5 out of 5 from 222 ratings, while 531 Strength averages 4.9 from 12K ratings.
Do 1RM Calculator or 531 Strength have ads?
531 Strength shows ads; 1RM Calculator does not.
Which is updated more often, 1RM Calculator or 531 Strength?
1RM Calculator ships an update every 3 weeks, and 531 Strength every 2 months. Most recently, 1RM Calculator was updated on October 23, 2026 and 531 Strength on November 1, 2026.

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