Comparison

Retro Flex vs The SIX

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

Head to head
About

Retro Flex

Features
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Welcome to the official app for retro flex gym, where you can sign into club, access workouts & much more!

About

The SIX

Features
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The SIX is the new way to rate your fitness. Built in collaboration with Gymshark, The SIX gives you a single performance rating across key pillars of fitness so you can finally show how good you really are in the gym. No guessing. No ego. No noise. Just your data, your effort, your proof. What you can do inside The SIX: * Complete structured fitness tests that cover strength, power, speed, capacity, endurance, and conditioning * Get your personal SIX rating based on your results * Track your progress over time as your rating increases * Create head to head comparisons with friends to see who wins, loses, or ties across each of The SIX * Record in-app video of your attempts so others can watch your lifts and efforts * Learn correct technique from Gymshark Lifting Club coaches with built-in movement guides and videos * Share achievement stickers and rating cards straight to Instagram and other social channels for social proof * Build social currency around your effort, not just your appearance * Compete on leaderboards and see where you stand The SIX creates a democratised rating for fitness. It gives every lifter and gym goer one clear number that reflects real performance, not opinion. Your training already matters. Now it counts. What is your SIX?

Screenshots

Retro Flex4 screens
The SIX4 screens

Verdict

The call

The clearest difference is update cadence: The SIX at weekly against Retro Flex's every 6 weeks. On price, ads, in-app purchases and device support there is nothing between them.

Scored on Price ยท Rating ยท Positive reviews ยท Number of ratings ยท Update frequency ยท Ads ยท In-app purchases ยท Monetization ยท Best chart rank ยท Devices ยท Requires iOS

CostPrice ยท In-app purchases ยท Ads ยท Monetization

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

Retro Flex ships an update every 6 weeks, The SIX weekly. The most recent releases landed on October 13, 2026 and October 5, 2026 respectively.

Scorecard1 real difference ยท 5 level
Retro Flex versus The SIX: the parameters behind the verdict, then further details
ParameterRetro FlexThe SIX
PriceFreeFree
Update frequencyEvery 6 weeksWeekly โ€” better
AdsNoNo
In-app purchasesNoNo
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.1 โ€” better15.6
Further details โ€” not scored
Size40 MB96 MB
Age rating17+17+
DeveloperFit Cloud Technology LimitedArchon Combine Limited

In-app purchases

None

Retro Flex

No in-app purchases

None

The SIX

No in-app purchases

Questions

Is Retro Flex free?
Retro Flex is free to download, with no in-app purchases.
Is The SIX free?
The SIX is free to download, with no in-app purchases.
Do Retro Flex or The SIX have ads?
Neither Retro Flex nor The SIX shows ads.
Which is updated more often, Retro Flex or The SIX?
Retro Flex ships an update every 6 weeks, and The SIX weekly. Most recently, Retro Flex was updated on October 13, 2026 and The SIX on October 5, 2026.

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