Comparison

Only One Calculator vs Conv3rtify

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

Head to head
About

Only One Calculator

This utility app offers instant currency exchange and unit conversions, making it ideal for travel and shopping. It features undo/redo functionality for easy editing and supports over 160 currencies with customizable update frequencies. Users can also access calculation history and customize the keyboard.

Highlights
  • Instant currency exchange
  • Unit conversion (length, weight, area, volume, temperature)
  • Undo/Redo functionality
  • History of calculations
  • Customizable keyboard layout
  • Real-time calculation results
Read full description

This calculator has instant currency exchange and unit conversion. With the "Undo" and "Redo" functions, you can go back to the previous steps and edit it. Select a specified currency exchange to be fixed to the calculator. When you input a number or expression, you can instantly know the conversion result, which is convenient for traveling and shopping. Features: • Can select a specified currency exchange and pin it to the calculator. During the input process, you can instantly know the exchange result, which is convenient for travel and shopping. • With the "Undo" and "Redo" functions, the calculator allows you to go back to the previous steps. It keeps up to 300 input steps for your review. So you don't have to worry about re-entering because of any mistakes during input. • Can choose between more than 160 currencies, and the exchange rate is updated manually or automatically per hour, day, or week. • The calculation expression and calculation result are recorded when pressing the equal button or clear button. You can insert the calculation expression or calculation result from a history record into the current calculation expression. • Can edit a very long calculation, and cursor control is very convenient and smooth. • During the input process, the calculation result will be shown instantly without pressing the equal button. • In addition to currency exchange, there are other conversion functions for length, weight, area, volume, and temperature. • If you need the Memory Buttons on traditional calculators, you can add them into the keyboard layout. ** Note: No Scientific Calculation Function. Not suitable for users who need Scientific Calulation. **

About

Conv3rtify

Features
Read full description

Conv3rtify is a powerful universal unit conversion tool that will make your life easier. In the app you'll find 3 main sections: - Standard, with some basic units (length, area, volume, mass, angle, time, etc.) - Pro, with more advanced and specific ones (colors, currency, base, and temperature conversion systems) - Favorites, where you can save the units you use the most — Pro features are available only with the Conv3rtify+ program. Upgrade to Conv3rtify+ to remove ads & unlock all the powerful capabilities of the app. It's a 1-time paying program: you pay once and you're able to use your app at 100% forever. When our team will come up with new cool features, you'll simply need to enjoy them and you won't be obliged to pay another time. — Conv3rtify also allows users to choose between 2 different themes: light and dark mode. There is even the possibility to select an automatic mode that will change the app's theme based on the device's theme.

Screenshots

Only One Calculator4 screens
Conv3rtify4 screens

Verdict

The call

The clearest difference is in-app purchases: Only One Calculator at none against Conv3rtify's 1. Only One Calculator also leads on update cadence (every 2 weeks vs every 26 months) and iOS requirement (11.0 vs 15.1). On price, ads 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. Conv3rtify sells 1 one-off in-app purchase. Only One Calculator asks for nothing beyond the download.

UpkeepUpdate frequency

Only One Calculator ships an update every 2 weeks, Conv3rtify every 26 months. The most recent releases landed on November 3, 2026 and November 7, 2026 respectively.

Scorecard3 real differences · 7 level
Only One Calculator versus Conv3rtify: the parameters behind the verdict, then further details
ParameterOnly One CalculatorConv3rtify
PriceFreeFree
Rating5.0 (2 ratings) — better—
Positive reviews100.0% of reviews—
Number of ratings2 — better—
Update frequencyEvery 2 weeks — betterEvery 26 months
AdsNoNo
In-app purchasesNo — betterYes
MonetizationFree—
DevicesiPhone, iPodiPhone, iPad, iPod — better
Requires iOS11.0 — better15.1
Further details — not scored
Size34 MB40 MB
Age rating4+4+
DeveloperJia Hua HuangIlya Emeliyanov

In-app purchases

None

Only One Calculator

No in-app purchases

1 purchases

Conv3rtify

One-time1
  • Conv3rtify+$2.99

Questions

Is Only One Calculator free?
Only One Calculator is free to download, with no in-app purchases.
Is Conv3rtify free?
Conv3rtify is free to download, with in-app purchases available.
Do Only One Calculator or Conv3rtify have ads?
Neither Only One Calculator nor Conv3rtify shows ads.
Which is updated more often, Only One Calculator or Conv3rtify?
Only One Calculator ships an update every 2 weeks, and Conv3rtify every 26 months. Most recently, Only One Calculator was updated on November 3, 2026 and Conv3rtify on November 7, 2026.

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