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Casio fx-991CW Scientific Calculator vs Casio FX-115ES Plus 2nd Edition

Both are Casio scientific calculators, but they suit different students. The fx-991CW is the newer ClassWiz model with a higher-resolution display, a menu-driven interface and QR codes that plot graphs on a phone. The FX-115ES Plus 2nd Edition is the older, proven workhorse with a Natural Textbook Display and 417 functions, and it is approved for the ACT, SAT and AP exams. Pick the CW for a modern interface and clearer screen; pick the 115ES Plus for exam-day familiarity and a lower-risk, well-reviewed choice.

  • Choose the Casio fx-991CW if you want the newer ClassWiz interface, a sharper display and QR code graph plotting on your phone.
  • Choose the Casio FX-115ES Plus 2nd Edition if you need a calculator approved for the ACT, SAT and AP and prefer the familiar Natural Textbook Display layout.

Prices

  • Casio fx-991CW Scientific Calculator: $25.99 at staples.com (last seen Nov 1)
  • Casio FX-115ES Plus 2nd Edition: $9.00 at eBay (last seen Nov 1)
  • Difference: the Casio FX-115ES Plus 2nd Edition is $16.99 cheaper than the Casio fx-991CW Scientific Calculator at the latest prices (Nov 1)
Casio
Casio fx-991CW Advanced Scientific Calculator

Casio fx-991CW Scientific Calculator

Casio fx-991CW Advanced Scientific Calculator

4.6(62 ratings)
$25.99at staples.comObserved Nov 1, 2026, 12:08 PM
See all prices and details
Visit staples.com
Pros
  • Sharper, higher-resolution display
  • Menu-driven ClassWiz interface is easier to navigate for complex functions
  • QR codes let you plot graphs on a phone
  • Slim body with a hard slide case
Cons
  • Fewer owner ratings to judge long-term reliability
  • Menu system takes time to learn
  • Exam approval varies by test, so verify before test day
Casio
Casio FX-115ES Plus 2nd Edition Scientific Calculator

Casio FX-115ES Plus 2nd Edition

Casio FX-115ES Plus 2nd Edition Scientific Calculator

4.7(225 ratings)
$9.00at eBayObserved Nov 1, 2026, 12:08 PM
See all prices and details
Visit eBay

Store links may earn us a commission.

Pros
  • Approved for ACT, SAT, AP and PSAT
  • 417 built-in functions including matrix and vector modes
  • Natural Textbook Display shows formulas as written
  • Long track record with a large base of positive owner ratings
Cons
  • Older two-line display is less sharp
  • No QR code or phone connectivity
  • Bulkier body than the CW

What separates them

Casio fx-991CW Scientific CalculatorCasio FX-115ES Plus 2nd Edition
DisplayHigh-resolution LCD with a menu-driven ClassWiz interfaceTwo-line Natural Textbook Display showing formulas and results together
InterfaceIcon menu and function keys, steeper learning curveDirect function keys, familiar to long-time Casio users
Exam approvalAccepted on many standardized tests, but check your specific exam's listExplicitly approved for ACT, SAT, AP and PSAT
ConnectivityQR code output to a phone for graph plottingNo connectivity
PowerSolar with battery backupBattery (LR44) with solar assist and auto power-off
BuildSlim plastic body, hard slide casePlastic body, hard slide-on case, slightly bulkier
FunctionsAdvanced scientific functions including equation solver and statistics417 built-in functions, equation solver, matrix and vector modes
Owner feedback4.6 out of 5 from 62 ratings4.7 out of 5 from 225 ratings

Price history

$25.99$9.00
Nov 1Nov 9
  • Casio fx-991CW Scientific Calculator: lowest $24.99 on Nov 9 at Office Depot.
  • Casio FX-115ES Plus 2nd Edition: lowest $9.00 on Nov 1 at eBay; $20.99 on Nov 9.

Prices at every store

Casio fx-991CW Scientific Calculator

  • TargetNew

    In stock

    $24.99+ $5.99 shippingObserved at 9:53 PM
    Visit Target
  • University of Alabama Supply StoreNew

    In stock

    $27.99+ $5.99 shippingObserved at 9:53 PM
    Visit University of Alabama Supply Store
  • staples.comNew

    Availability unknown

    $25.99Observed Nov 1, 2026, 12:08 PM
    Visit staples.com
  • eBayNew

    Availability unknownSold by diversegoodsdepot (99.8% positive, 2,300 ratings)Returns: Set by the eBay seller; the eBay Money Back Guarantee covers an item that doesn't arrive or isn't as described.

    $20.00+ $6.66 shippingVerified
    Visit eBay

Also available at

  • WalmartCheck price at Walmart
  • eBayCheck price at eBay

Store links may earn us a commission. Some prices via Klarna.

All 9 stores and price history →

Casio FX-115ES Plus 2nd Edition

  • QuillNew

    In stock

    $20.99Observed at 9:53 PM
    Visit Quill
  • SchoolMartNew

    In stock

    $21.99Observed at 9:53 PM
    Visit SchoolMart
  • QuillNew

    In stock

    $20.99+ $5.99 shippingObserved at 9:53 PM
    Visit Quill
  • eBayNew

    Availability unknown

    $9.00Observed Nov 1, 2026, 12:08 PM
    Visit eBay

Also available at

  • WalmartCheck price at Walmart

Store links may earn us a commission. Some prices via Klarna.

All 14 stores and price history →

Specs compared

SpecCasio fx-991CW Scientific CalculatorCasio FX-115ES Plus 2nd Edition
ColorGrayWhite
size6.4" tall x 3.0" wide x 0.4" deep.38" x 3" x 6.38"
TypeHandheldCalculator
Solar PoweredYes—
Digit Count2 digits—
Calculator Type—Scientific, Handheld
Printing—No
Display Digit Count—10 + 2 digits
Display Type—LCD Display
Display Line Count—2
Alphanumeric Display—Yes
Power Source—Battery
Show all 36 specsShow fewer specs
SpecCasio fx-991CW Scientific CalculatorCasio FX-115ES Plus 2nd Edition
Battery Size—LR44
Rechargeable Battery—Yes
Included Items—Cover
Dimensions—6.4 in (Length)
Educational Level—High school, College
Typical Users—Students
Skill Level—Advanced
Age Range—Adult
Key Type—Plastic keys
Body Material

What reviewers say

Casio fx-991CW Scientific Calculator

  • 4.6 / 562 ratings

Owners rate the fx-991CW highly, with 4.6 out of 5 from 62 ratings. Most praise the sharp display and the easier menu system, while a few miss the direct keys of the older fx-991EX.

What people mention
  • DisplayPraisedOwners say the high-resolution screen makes fractions, roots and long equations easy to read.
  • InterfaceMixedThe icon-based menu is praised as easier to learn but criticised as slower than direct function keys.
  • BuildPraisedReviewers describe the calculator as sturdy and well made for daily classroom use.
  • PowerPraisedThe solar panel with battery backup is reported to keep the calculator running without frequent battery changes.

Casio FX-115ES Plus 2nd Edition

  • 4.7 / 5225 ratings

Owners rate it highly, praising its natural display and the breadth of functions for the price. Complaints center on the learning curve for its modes and the limited two-line screen.

What people mention
  • DisplayMixedOwners like the natural textbook entry but find two lines too few for long expressions.
  • FunctionsPraisedReviewers value the calculus, matrix and vector features at this price.
  • Ease of useMixedThe mode menus take practice before they feel quick.
  • BuildMixed

Questions and answers

Which is better for the SAT or ACT?
The FX-115ES Plus 2nd Edition is explicitly approved for the ACT, SAT, AP and PSAT. The fx-991CW is accepted on many tests, but check your exam's approved calculator list before test day.
Which has the better display?
The fx-991CW has a higher-resolution screen and a menu-driven interface. The FX-115ES Plus uses a two-line Natural Textbook Display that shows formulas and results together.
Which lasts longer?
Both are durable Casio calculators with hard slide cases. The FX-115ES Plus has a much larger base of owner ratings, which gives more evidence of long-term reliability.
Is the fx-991CW worth stepping up to?
Yes if you want a sharper screen, a modern menu interface and QR code graph plotting. If you mainly need exam-approved basics, the FX-115ES Plus covers them.
Can either solve equations?
Both can solve equations. The FX-115ES Plus handles simultaneous linear equations, quadratics and cubics, plus matrix and vector calculations up to 3x3.

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Buying guides that pick them

  • Best calculators under $100
—
Plastic
USB Port—No
Keys—Regular size
Width (")—56.0
Weight (oz)—7.0
Height (")—9.1
Features—Statistical Functions, Solar Powered, Battery O…
Depth (")—1.0
Number of Display Lines—2
No. of Batteries (pcs)—1
Battery Life (h)—26298.0
Display Characters per Line—12
Battery Type—LR44
Display—Monochrome
Multipack Quantity—1
The plastic body and keys are durable but feel light and small.