Monday, July 19, 2010

Single-Purpose Devices Replaced by a Smartphone

Smartphones, like the iPhones made by Apple and the phones utilizing Google’s Android operating system, have been big news the last couple of years.  The prices are also big, particularly when compared to “traditional” cell phones -- those single-purpose devices that primarily serve as a phone and texting device.  The cost of a subsidized iPhone 4 (with 32 GB) or a Motorola Droid X is $199 at the time of this writing (July 2010). Subsidized means a two-year contract with a wireless provider is required to obtain the subsidized price.

But the price of a smartphone should be put into perspective.  These phones are really highly mobile computers, not quite as powerful as laptops, but in some ways even more functional than laptops because of their unique hardware capabilities (see this posting on the hardware capabilities of Apple’s iOS devices for an in-depth description.)  The unique hardware capabilities, combined with their small form factor (fits in a pocket) and sophisticated software, allow smartphones to replicate the functionality of several single-purpose devices as well as provide new classes of functionality.

Here is a thesis:  A smartphone can be cost-justified, and perhaps be a money-saver, when compared to the cost of buying several single-purpose devices.  The assumption, of course, is the user would be purchasing some or all of these separate devices in the absence of having a smartphone and has not spent the money on acquiring them yet.

This posting presents this thesis by:
  • Describing the different categories of costs associated with smartphones
  • Presenting a list of single-purpose devices a smartphone can replace
  • Comparing the total costs of these single-purpose devices to smartphones to test the thesis
  • Describing additional cost-saving features and benefits of smartphones that may also help justify the purchase.
The thesis is applicable to several smartphones on the market, including the iPhone 4, HTC Evo 4G, and Motorola Droid X, among others.  I have used the iPhone 4 costs, features, and apps in this posting as the smartphone for comparison against single-purpose devices.

The information in this posting will be updated as more single-purpose devices that can be replaced by a smartphone become known and are logged.  Please send me an e-mail if you have suggestions or use the Feedback link in the menu.


There are five types of costs associated with a smartphone.  These should be kept in mind in any smartphone purchase.
  • The cost of the smartphone hardware.  This is a one-time cost.
In this thesis, the subsidized price of the smartphone is used as the hardware cost.  The "traditional" cell phones are assumed to have zero hardware costs—they are typically subsidized and given free with a contract.
  • The cost of a data plan.  This is usually a monthly cost to send and receive data (provide connectivity) through cellular service.
In this thesis, I include this cost because some of the functionality to replace single-purpose devices require connectivity, and the smartphone should able to replace a single-purpose device almost anywhere that device typically works.
  • The cost of a voice plan.  This is usually a monthly cost to send and receive voice calls through cellular service.
In this thesis, the assumption is a "traditional" cell phone is definitely one of the single-purpose devices being replaced.  Therefore, the voice plan is not included in the relative cost comparison, that is, the cost for a voice plan would still exist and be the same for either a "traditional" cell phone plan or a smartphone plan.
  • The cost of the smartphone applications (app).  These costs vary, from free to several dollars, depending on the developer and/or the features provided.
In this thesis, free apps are used if they provide a roughly equivalent level of functionality compared to a single-purpose device.
  • Subscription or other costs associated with the smartphone app or service.  Some apps may require a subscription to continue using the service or having the most up-to-date information.  For example, one iPhone car navigation app charges an annual fee if you want voice turn-by-turn directions.  As another example, in the United States, ATT charges a monthly fee to allow the smartphone to act as a cellular modem for a laptop (called tethering.)
In this thesis, any subscription or other costs are computed over a two-year period.


The following single-purpose devices (SPDs) have been categorized as being partially (but adequately) replaceable, fully replaceable, or fully+ replaceable by a smartphone.  This categorization is subjective based on my opinion.

Partially Replaceable
  • Flash drive
  • Point and shoot pocket camera
  • GPS device for driving
  • Radio
  • Portable DVD player
  • Portable gaming device
  • Landline phone
  • Netbook
  • eBook Reader
Fully Replaceable
  • Cell phone
  • Small video recorder
  • iPod
  • Keychain light
  • Wrist watch / stopwatch
  • Compass
  • Mobile GPS device for hiking/sports
  • Level
  • Pocket calculator
  • Pocket voice recorder
  • White noise machine
  • Four-note ocarina
  • Dog whistle
  • Police band radio
  • Notebook for notes
Fully+ Replaceable
  • Maps
  • Travel alarm clock
  • Pocket calendar
  • Pocket address book
  • Pocket dictionary
  • Pocket thesaurus
  • Recipe book
  • Travel electronic chess game
  • Dice
  • Holy Bible

A spreadsheet has been created which lists these single-purpose devices and the reasoning for its categorization.  Click on the spreadsheet graphic to view the spreadsheet.

(Click to access the spreadsheet -- Located on the Replacement List tab)
The spreadsheet contains additional columns of information about each single-purpose device:

Column Name Description
Single-purpose device (SPD) The type of single-purpose device that can be replaced by a smartphone.
SPD example A specific example of that single-purpose device.  A low-priced example has been chosen, typically with standard functionality for that SPD.
SPD cost The cost of the single-purpose device.
Cost source and date Where the cost was noted and date it was noted. was used to find the costs for most of these SPDs because of their low prices and good reputation.
iOS app example The name of a specific iOS app that provides the functionality of the SPD.  If a free app is available, it has been selected.
App cost The cost of the app in Apple's App Store as of the same date noted for the SPD cost.  
App other cost Any additional costs associated with the app or service to allow replacement of the SPD.  This cost is the amount required to be spent over a 24 month period.
Replacement level A subjective rating on the level of replacement of the SPD by the smartphone with the app installed.  Levels:
  • Partially:  partially replaces the SPD, but the smartphone does an adequate job to serve as a replacement in most situations
  • Fully:  fully replaces the SPD
  • Fully+: fully replaces the SPD and even provides better functionality
True for iPod Touch 3rd? An "X" signifies that an iPod Touch 3rd generation could be used to replace the SPD in off-line mode (no connectivity) or with Wi-Fi connectivity.  While not as powerful as a smartphone with cellular capability, the intent is to allow this spreadsheet to also be used in cost-justification of an iPod Touch.
Notes Comments associated with the line item in the spreadsheet.

Care was taken not to overload this list and exaggerate the costs and comparison.
  • Only single-purpose devices that could be used by a large population are included.  Niche devices, like oscilloscopes that can be replaced by a smartphone, are not included.
  • Only one example for each group of similar types of single-purpose devices is included in the list.  For example, a smartphone can replace the cost of several board games, including checkers, chess, chinese checkers, go, etc.; however, only a portable electronic chessboard has been listed.
  • Low-end or medium-end single-purpose items have been selected.  High-end models have not been chosen.  For example, there are several high-end ebook readers available; however, a smaller, lower-cost Sony model was selected.
  • Discounted prices, not retail prices, have been used.  Specifically, was used to determine prices of most items, all at a discount.
The spreadsheet also contains a column at the far right titled Place "X" for Your Situation.  This will compute the total cost related to the single-purpose devices you choose to put in your own calculation.


A spreadsheet on a second tab labeled Relative Cost Comparison contains the cost comparison.  Below is the cost comparison if all of the single-purpose devices documented were compared.

Cost Category
SPD cost
Smartphone cost
Hardware device
Assumes including all SPD's listed in Replacement List tab in the comparison.
Data plan
Assumes cost of a $25 per month data plan for 24 months.  None of the SPD's chosen use a data plan.
Voice plan
Assumes a "traditional" cell phone with a voice plan in the comparison.  Replace with the cost of your voice plan as part of a total cost of ownership.
Total cost of the apps to replace all of the SPD's.  See spreadsheet in the Replacement List tab for breakdown.
Total cost of subscriptions over 24 months.  See spreadsheet in the Replacement List tab for breakdown.
Total cost
The relative cost difference over 24 months

If your situation does not support the comparison of all of these single-purpose devices, you can download this spreadsheet.  Make changes to the column at the far right titled Place "X" for Your Situation on the spreadsheet in the Replacement List tab.  This will compute the total cost related to the single-purpose devices you mark with an "X" and automatically update the spreadsheet on the Relative Cost Comparison tab.


There are a number of niche applications for smartphones that are of great benefit to certain individuals.  Buying an equivalent single-purpose device may be more costly and may not be as functional or beneficial.  These replacements could be added to your overall comparison.  A few examples:
  • Star Walk (Vito Technology):  This is a personal planetarium.  A user can use it to identify all of the celestial objects in the sky in front of you in real-time or at any date you wish.  The application is $2.99 in Apple's App Store.  Purchasing a stargazing book would be more expensive and less functional.  Purchasing a Celestron SkyScout Personal Planetarium single-purpose device costs $212.29 (, July 17, 2010), more than the cost of a subsidized smartphone hardware.
  • Bird reference guides:  There are a number of apps available from National Geographic to the Audobon Society.  These go beyond typical field guides and provide functionality like searching, identification, and listening to bird songs.
  • SignalScope (Faber Acoustical):  This app turns an iPhone into a real-time spectrum analyzer and oscilloscope.  A very niche market, but for those in need of the capabilities provided by the app, it could help offset the cost of purchasing a single-purpose device equivalent.
Some of the smartphone apps can also be used to save money in other areas of your life.  These examples are mainly for the U.S. market, but there may be equivalent apps for other parts of the world:
  • RedLaser (Occipital):  A user can scan (or enter) the barcode of thousands of products and see the prices of the same products from several retailers.
  • Gas Buddy (Bottle Rocket):  This app shows the gas prices from nearby gas stations so the user can pick the place with the lowest price.  From the developer's own advertisement:  "Want a Free iPhone?  Gas Buddy will pay for itself in one take of gas and will pay for your iPhone after one year of use.  We're not kidding.  We didn't believe it at first either."
  • Amazon Mobile (Amazon):  A user can do price comparisons and read reviews before making purchase decisions.
  • CardStar (Mesa Dynamics): A user can store and retrieve loyalty, reward, and club membership cards, which is helpful in getting discounts and earning reward points.
There are a number of benefits of having a smartphone, independent of the outcome of the cost comparison.
  • Availability:  A smartphone is more likely to be with you than many of the single-purpose devices.  This means a user will tend to use the functionality more.  How many times have you wanted to use your camera or video recorder but you did not have it with you?  Had a few minutes to read but did not have the newspaper or book with you?
  • Convenience:  A smartphone takes up less space than most of the single-purpose devices listed.  Carrying several single-purpose devices at the same time requires a purse or bag, which may be inconvenient and therefore, less likely to be available.
There are some disadvantages of a multi-purpose device like a smartphone compared to several single-purpose devices.  Keep these in mind if they apply to you.
  • Lending:  A single-purpose device can be lent to a colleague or friend.  A smartphone is less likely to be shared, and it cannot be in two places at once.
  • Selling:  A single-purpose device can be sold or given away once its use is finished, perhaps recouping some or all of the cost of the device.
  • Losing/breaking:  The loss of a smartphone will negatively affect a user much more.


If you have additional suggestions, please send me an e-mail at daniel @ with the SPD name, SPD example, iOS app equivalent, and any notes.  I will review and add to the spreadsheet.

Happy replacing!

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Single-Purpose Devices Replaced by a Smartphone ~ DANIEL SKLAR