handyCalc was born during a cold winter in Shanghai. In those days, there was a huge snow fall in the city.

handyCalc means calculate in your hand. It’s designed as it’s said: “Solve things in your hand.”

I decided to design this calculator since I saw that Google Android challenge. At this point, I’m still a college student studying civil engineering in Shanghai.

When the first release of handyCalc 0.1 was finished, it took about 35000 lines of Java code which was written in about 4 months. It almost drive me mad to do so much coding.

handyCalc eventually failed in Google’s ADC in 2008.

Life is always like that, though. Two months after ADC, I left the college and started a new life working part time by day, and programming by night.

handyCalc hasn’t  changed much since version 0.1. It’s not the only project i’m working on, but it doesn’t leave me time for much else.

If you do think handyCalc is useful to you, you can donate this project. Or, you can simply rate a FIVE STAR in the market to make it known to other people.

Dec. 3, 2008




Donate handyCalc!

90 Responses to About

  1. Mariano Corzo says:

    Seriously, i can’t belive you didn’t win. Please carry on with the project, i’m sure everybody’s gonna use the app. I made a comment in other post before seeing this.

  2. Flak says:

    Yeah this is crazy, this calc should be in android, but I dont know why? I saw the list and I’m sick on those help, emergencies apps.

    I will tell you to port on Iphone, maybe you will find more respect, but leave it for android too.


    Keep on working

  3. Danny says:

    Hey there,

    It’s a shame you didn’t make it on the list, but I have an offer for you. I’m the owner of AndroidBoards.com, you may have run across it in your Android research. I am doing a series of interviews on great apps that missed the ADC list. I would love to feature yours, as it’s definitely that I feel should have made it. Please e-mail me at admin@androidboards.com if you’d like to be featured. I’ll send you some interview questions and we’ll go from there.

    Sorry to contact you through this, I saw no e-mail address on the site that I could get in touch with you with.


  4. plusminus says:

    Hell mmin,

    I hope you did not give up this excellent project ?!?!?

    Best Regards,

  5. Kavik Bachani says:

    Hi mmin,

    I tried installing your application but i am getting the following error:

    I recently upgraded to the latest SDK. Do you thing it can be because of that.
    Could you update the .apk file with the one that works on the latest SDK.

    BTW, your calculator ROCKS!!


  6. Awesome program. I was contemplating writing my own graphing calculator or porting something like gnuplot or octave to Android, but this is much better than I would have thought to do–the automatic solving and suggestion of actions on what’s written is really convenient.
    I’d like to see it go open source. There are some additional features I’d like to see (and could submit patches for): support for non-decimal bases (hex, octal, binary) and the multiplication symbol on the G1 keyboard (×). I could also help port it to iPhone as I have some experience writing iPhone programs and porting to iPhone.

  7. asantoso says:

    Awesome program, will you make it open sourced?

  8. Guillaume says:

    Great calculator! I donated you $10! Thanks
    (would be even greater if it was open sourced)

  9. Bernardo says:

    I really enjoy this aplication, Its one of the bests I’ve seen on the market at the moment. Anyway I would like to suggest/beg for a change or new implementation. I miss somehow some small feature, wich is work in binari, making binari calculations, at the moment the calc just makes unit conversion, would be awesome if you could work on it to make it make some basic operations on binari. Anyway, awesome job with this little tool. Thank you very much.

  10. Patric Bechtel says:

    I’m absolutely excited about your app. Can’t believe this isn’t included in the standard Android distribution already.
    Kudos to your great work, keep it up!

  11. Nikos says:

    This is an amazing app.
    To be honest I hardly use much of the extended functionality, but still have it on the front page of my Hero to showcase to people how powerful Android apps can be.. “Solve for x”.. Awesome!
    I can’t believe you didn’t make it on the ADC – clearly gimmicky social, networking and shopping apps do a lot better than an excellent working tool such as this! Keep it up!
    All the best,

  12. WSY says:

    Best thing I’ve seen.

    I’m making a donation now.

    I hope you open source this, or at least keep it ad-free; it’s that good.

  13. Roald says:

    I would just like to add my voice to the praise.
    This is such an excellent app.
    My appreciative donation is already placed on PayPal.

    My TI-89 calculator is gathering dust after I found HandyCalc.

    The only thing I miss, being a grumpy old git, is a printable (pdf) documentation.

  14. SCM says:

    This app is just great. My favorite app in Android world. Now my DROID is always in low battery because of this.

    Thanks mmin!

  15. Harmen says:

    Works great. Is there a twitter stream for future updates especially in the currency and unit covertor bits of the application?

  16. David says:

    Great Work! Please don’t give up on this project, we need you!

  17. Lionel says:

    HandyCalc helped me so much in advanced functions to understand how they worked, helping me to learn the rules of algebra as well.
    Thank you for this amazing program.
    I will be donating when I get into my co-op at university🙂.

  18. Christoph says:

    Would be great to have your handyCalc application as a extension application in the google chrome browser (see https://chrome.google.com/extensions).
    Congretulations for your work!

  19. Gustavo says:

    How do i put modulo on a number or variable?

    Great app thank you for exist!

  20. B says:

    Hi! I really like seeing what the calculator can do! Why does the program need full internet access?

    I much rather pay a reasonable price than have my bandwidth be used used by an application for ads.


  21. Mike says:

    Is this app dependent on having a physical keyboard? I have an HTC Incredible, which does not have a physical keyboard, and I can’t figure out how to use variables other than x, y, and z.

    • works great on my incredible, you can use your regular on screen keyboard for almost everything but it also has it’s own limited keypad to use. also have not been able to figure out absolute values on it and it does not calculate imaginary numbers like negative square roots…college algebra class i’m in works with imaginary numbers a little so i just do it all on paper and use this to check the answers

  22. BerkleyJ says:

    How do you use this on the 90% of android phones that don’t have a physical keyboard? Including almost every HTC phone, and google’s own Nexus One.

  23. Criss says:

    Realy nice tool🙂
    it has everithing i need.
    Just Matrices and differential equation would be nice.
    Go on *thumbsup*

  24. CH Lee says:

    Great app. I wish this app was available to me during college days!


  25. sig says:

    thank you so much (especially for the graphing capability, and the fact that you’re providing it for free).
    definitely 5 stars!

  26. Massimo says:

    I don’t have an hardware keyboard… this is why I use Arity calculator…

    • Criss says:

      Criss says:
      September 28, 2010 at 9:12 pm

      Try to hold the menu button to get your softkeyboard

      • Jacob Feisley says:

        Holding the menu button does not work on any of my Android 2.2 devi es. Could an option to toggle the OS keyboard be added to an update?

  27. robert says:

    Thank you very much for this marvellous calculator. And the best is that it is free of charge.

  28. Matthias says:

    Man, I am honestly impressed about your app!
    Greetings from Germany to Shanghai!

  29. Maxmara says:

    Dear Sir,
    Sorry to contact you through this, I saw no e-mail address on the site that I could get in touch with you with. Being one of the OEM supplier of computers and computer components in European, Middle East and African markets, the company ASBISC Enterprises PLC, I work for, launches its new multimedia device based on Android platform with Handy Calc preinstalled on it. In that way, I would kindly request you to provide me with the information on licensing of distribution of Handy Calc software preloaded into our product. Please, email me how to obtain the license on M.Maksimova@asbis.com. Thanking you in advance.

    • handycalc says:

      Hi Maksimova,

      I authorize you to preinstall handyCalc on your device, without charges.

      I don’t know how to write a legal license, so if you really need one, please provide me a template.

      Regards, mmin

  30. Paul says:

    Thank you for this great piece of software!
    One thing though: it would be great to have translations for handycalc, I cannot always remember the English names of units and currencies.

    Greetings from Germany

  31. Peter says:

    It’s a great tool, but probably I’ve found a bug in the function plotting. I tried to plot (2/x-1)/(x-2). The shown graph was like -(1/x). I tried it several times with the same result.


  32. jeff popek says:

    Is there a way to do absolute values on the handycal if do please let me know thank you

  33. John Romero says:

    I love this app, I used it on my phone as my default calculator.

    Are there any plans to launch it with support for big screen such as motorola xoom? It appears very small there.

  34. Ye Youqun says:

    handyCalc is a great app, I am interested in it when I first try it, It may become more powerfull if some parts of it are enhanced:
    1. Support mathematics formula in more natural style, such as a circle’s funtion is x^2 + y^2 = R^2, or (sorry for typing square like this).
    2. “swipe” the keyboard not so smothly.It often wrongly input the symbol but not “swipe” the keyboard.

    But after all, It is really fatastic tools, thanks for your invaluable work.

  35. Matt says:

    First of all, thanks for the great calculator.

    Some feature requests for future versions; formatting of large numbers with thousand separators (e.g. 1,000,000) to make easier reading.

    For the currency converter, being able to change the base currency so that you can see the conversion rates based on your home currency rather than through USD.

    Thanks again for the great work.

  36. Kevin Lee says:

    any solution to display problems for large format screen like “HTC Flyer” with 1024×600 pixel.

  37. Stephan says:

    Really great tool!

    There is one problem, I could not solve. I saved a lot of calculations, this feature could be extremely usefull. But program stores files somewhere.

    Everything was lost after a needed new installation of OS. It is not possible to transfer calculations to another phone.

    Or is there a possiblity to backup/save everything to SD card?

    Thank you!

  38. voy says:


  39. Ara says:

    Is this program open source?

  40. Javier says:

    Why does it need Full internet access?

  41. John says:

    Has this app been optimized to be used on the new generation of tablets such Samsung Galaxy Tab, Asus Transformer, Acer Icona, etc?

  42. Ettor says:

    The application crash at the very beginning with the 2.3 android update…

  43. David says:

    This is a great program. Thank you.

    I do have an error report: e^(-36933/8.314×298.15) = 0 in “normal precision with scientific notation” mode. It equals 3.382659680249225e-7 in “Maximum precision of your system” mode.

  44. Umar says:

    Hi, I am missing this calculator on iPad. Any ideas is it coming to iOS? Thanks

  45. João Dias says:

    Thank you very much for this app! Amazing!

    Would be great if you made a version for Chrome!

    Thank you!

  46. Anonymous says:

    My biggest wish is to open-source (GPL!) the code, so other people could extend it.

  47. rephael says:


    My name is Rephael, I work in a company called Startapp (www.startapp.com).
    I recently came across your app, handyCalc Calculator and wanted to introduce myself and offer you our unique monetization solution that can significantly increase your app revenue.

    We are introducing a new way to monetize Android apps – Search. Utilizing the power of search based revenue, we offer you, the developer, a fixed payment for every download your apps make! Integrating our SDK can generate up to $50 for every 1000 downloads of your applications. The revenue we offer you is up x4-x10 more than any ad network out there!
    I’d be happy to answer any question you may have here.

    You can learn more and sign up on our site – http://www.Startapp.com


  48. Anonymous says:

    Amazing App, I rated 5 stars in market and donated

  49. kenny says:

    Hi MMIN. I love your calculator app. Is there any possibility that you can develop the Blackberry Playbook version of it. Blackberry AppWolrd lacks quality calc apps and I am pretty sure that, even if you make handycalc a paid app (e.g. $1.99 – $4.99) it will be a tremendous success. I myself will make sure to spread the work on Crackberry.com as soon as the app is released. Thanks.

  50. Michel Merlin says:

    BIG bugs with NO reply or consideration
    There are a few BIG bugs in HandyCalc, that are preventing from relying on it for any serious use. Some are explained on https://handycalc.wordpress.com/download and are still waiting for consideration or at least reply. Please address them.

    Versailles, Fri 10 Feb 2012 21:21:21 +0100

  51. Anonymous says:

    Really cool tool. Like it very much. I like the GUI and the usability. I use it almost every day in conjunction with the Android Octave Editor available at https://www.verbosus.com/android-octave-editor.html

  52. Gerhard says:

    Bug ‘Copy Answer’ with other Language: If you Change the Language to German theres a bug. When you use ‘Copy Answer’ and past the data to another application the data is pasted not as text. There is clipboard text like ‘HandyCalcRawData’.
    If you change the Android System Language to English everthing works fine.
    From my point of view the problem ist that in German the result contains comma as delimiter for decimals. In English the dot ist the delimiter.
    You can see this if you paste the answer back in handy calc. Then you see that the pasted text contains a comma and is interpreted als function in handycalc.

    But I really like handycalc, allthough my android now ist English🙂

  53. Anonymous says:

    Hmm, I have one problem, where is the menu button, I cant get there, I dont see it, pressing the icon just make blue aura and do nothing so is a bug ?😦
    I have HTC Sensation XE

  54. Anonymous says:

    no, find it, the mobile menu button, never worked on any app which I have before, so I dont even try it😀

  55. blue.S says:

    Thanks for this amazing work! Any news about iOS version?

  56. joe says:

    A negative number squared becomes positive. You need to fix this. Thanks.

  57. Greg Yang says:

    This is GregYang from Transpac Inc. If you have L10N business requirement, pls feel free to contact me.

  58. Anonymous says:

    Great Application, work perfect for me. The best app (calculator) I’ve tried.
    Congratulations and please…. Go on with this!!!

  59. Rabe says:

    Please make it for iphone aswell!!

  60. Sergey says:

    Good work. But I wanna suggest some improvements for next version:

    – hide and delete pages ability
    – arrows to navigate on formula
    – hide keyboard ability
    – stack support

    • Sergey says:

      Sorry – keyboard can be hidden completely. But I suggest hide only left alphabet part to make entire formula field visible in landscape while digital keys are visible too at right.

  61. blake says:

    I love this app except i cannot read the points on the graph function as they are too small. Is there a way i can make them bigger or could you add a way to enlarge them please, it would be much appreciated, Other than that wonderful and very useful app!

  62. Toine says:

    I like the calculator and am using it for a while now. I really like the fact that I can see my equation.

    A great improvement would be to add engineering symbols, like p, n, µ, m, k, M, G. This is really helpful for engineering calculations. A calculation would then look like: 0.1m/10k. The answer would be; 10µ.

    A cursor left/right would also be useful, as I struggle to set the cursor on the right position to edit my equation

    Many thanks, Toine.

  63. Alex says:

    This is an excellent app! I tried to make a donation, but Paypal isn’t accepting either of my credit cards. Is there a different donation option?

  64. Ur post, “About handyCalc” was in fact truly worth commenting on!

    Just simply needed to say you did a superb work. Regards ,Dorie

  65. Lucas says:

    I can not believe it. This is quality, honest, constant work. How is it possible that you first world guys are spending billions on feathers and this dev does not get some money to keep improving this ?

    Dev. I understand your frustration but you should go proactive now. Let users bid for new functions, create a roadmap to a year, set a price for some of your hours/week and ask for a donation based on that sum of work. Go Open Source, let us help in other ways.

    Anyway, this deserves continuity.

  66. Matthias says:

    Very cool application. I’m a bit of a Math Geek I like and use it a lot.
    One point/question is I can’t find the currency RSD (Serbian Dinar). Probably because it is not on the ECB website. Is it possible to include your “own” currency somehow manual?
    Anyway good app! Please continue with your good work.

  67. Stefan says:

    Hey mmin,

    thank you very much for creating/updating this wonderful app. I’m using it very often, since it is soooo useful. I would like to donate, but from PayPal it says that only accounts from China can do that. Please if you have another mean where we can pay, put it on your website, so that the thousand, I believe, people who appreciate your work can show their financial support for you.

    Peace Out

  68. Anonymous says:

    one of the few apps where I would give more then 5 stars

    brilliant and awesome – and I don’t even need a calculator that often. But fractions and variable make this thing awesome.

    I still need a currency converter as standalone – yours does the job but kinda not intuitive

  69. url emusic says:

    Your means of describing all in this piece of writing is in fact nice, all be capable of without difficulty understand it,
    Thanks a lot.

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  74. darren says:

    Love this calculator!! Please add way to remove pages. Sometimes I bump CE and add a new page. Would be nice to remove. Thanks for building. Love it!

  75. Isaac says:

    Help! All of a sudden, when I try to open your wonderfull program it says: “Expired The current version of handyCalc (0.56) is out of date, please update to the new version (0.56).” There is no way to update, even uninstalling and re-installing from the Play store gives the same result…

  76. Isaac says:

    Thanks for fixing this version problem now it updated to v 0.57

  77. A76 says:

    Sorry, I cannot write English. Please calculate 100-99.9

  78. Guilherme says:

    I understand you didn’t make this app for living. It would be asking too much for you to add the collon sign on the keyboard to make working with time easier? This is a very well designed application. Congratulations!

  79. Ilya says:

    I have improvement. In my country was held denomination of currency and currency has changed from BYR to BYN. Please add BYN currency to “Currency Converter” in your app.

  80. guy says:

    Such a useful app, thank you!

    Would you consider adding more functions?
    Or better still (and less work for you perhaps) adding a way to make a user function persistant, so it can be used in all new documents? For example I could define tanh(x), make it persistent, then it would always be available.

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