Why do engineering students use the fx-115ES Plus?

It is non-programmable and not CAS, and NCEES lists the Casio fx-115 line for the FE and PE engineering exams. Casio's manual lists 40 built-in scientific constants, metric conversions, equation solving, matrices and vectors.

How do you enter Planck constant on a calculator without a CONST key?

Type 6.62607015, press EXP, then the minus key, then 34. The value is 6.62607015 x 10^-34 joule seconds.

What is the energy of a photon at 5 x 10^14 Hz?

E = h x f = 6.62607015E-34 x 5E14 = 3.313035075E-19 joules.

What can the real fx-115ES Plus do that this page cannot?

Built-in constants and conversions, textbook fractions, cubic and simultaneous solving, complex numbers, vectors, larger matrices and numeric calculus.

Casio fx-115ES Online: Free Scientific Calculator (2026)

This is a free Casio fx-115ES online alternative for engineering and college maths. It runs trig, logs, powers and memory in your browser, and it comes with something the real calculator hides behind a key: the exact constants and unit factors you would press CONST and CONV for, ready to type in with the EXP key.

Results shown to 10 significant figures. Uses standard order of operations (PEMDAS).

Is There a Free Casio fx-115ES Online?

Casio sells an ES-series emulator aimed at teachers, and we found no free public web version of the fx-115ES Plus. This page is a free Casio fx-115ES online alternative for the core scientific functions. It does not copy the menus or the textbook display, so use it for homework and for checking your steps, and keep the real calculator for exams.

Why Do Engineering and College Students Choose the fx-115ES Plus?

It is a non-programmable, non-CAS calculator with a natural textbook display, equation solving, complex numbers, matrices, vectors, statistics, and 40 built-in scientific constants plus metric conversions, according to Casio's manual. NCEES lists the Casio fx-115 line for the FE and PE engineering exams, which is a big reason it shows up in university courses.

Casio fx-115ES Online Key Guide: Where Is Each Key?

Key on the fx-115ES Plus	What it does	On this page
CONST	Inserts a scientific constant	Type the value from the table below
CONV	Converts between metric and other units	Use the exact factors below
CALC	Re-runs an expression with new values	Not available, edit the line or use history
SOLVE	Solves an equation numerically	Quadratic solver in Extended Functions
MODE, then Stat, Matrix or Vector	Special modes	Statistics and 2×2 matrices in Extended Functions
SHIFT, then MODE	Sets degrees or radians	Deg and Rad buttons above the display
Ans	Reuses the last answer	Tap an earlier result in the history panel

Which Constants and Conversions Can You Type Into This Page?

These are the exact values defined in the SI system since 2019. A calculator built before then may store slightly different older values, so the last digits can differ. On this page, use EXP for powers of ten, then the minus key for a negative exponent.

Constant	Value	Type it as
Speed of light, c	299,792,458 m/s	299792458
Planck constant, h	6.62607015 × 10⁻³⁴ J·s	6.62607015, EXP, minus, 34
Avogadro constant	6.02214076 × 10²³ per mol	6.02214076, EXP, 23
Boltzmann constant	1.380649 × 10⁻²³ J/K	1.380649, EXP, minus, 23
Gas constant, R	8.314462618 J/(mol·K)	8.314462618
Standard gravity, g	9.80665 m/s²	9.80665

Exact conversion factors: 1 inch is 25.4 mm, 1 mile is 1.609344 km, 1 pound is 0.45359237 kg, and 1 US gallon is 3.785411784 L.

Worked example: energy of a photon

A photon with frequency 5 × 10¹⁴ Hz has energy E = h × f. On this Casio fx-115ES online page, type 6.62607015 EXP minus 34, then ×, then 5 EXP 14, and press equals. The answer is 3.313035075 × 10⁻¹¹ joules, shown as 3.313035075E-19.

Worked example: molar volume of a gas

Use PV = nRT with n = 1 mol, T = 273.15 K and P = 101,325 Pa. Type 8.314462618 × 273.15 ÷ 101325. The result is about 0.022414 cubic metres, which is 22.414 litres, the molar volume of an ideal gas at 0 °C and 1 atm.

Table comparing the real Casio fx-115ES Plus with this free Casio fx-115ES online alternative on constants, solvers, statistics and exam use — The fx-115ES Plus compared with this page.

What Does the Extended Functions Panel Cover in This Casio fx-115ES Online Alternative?

Statistics gives count, sum, mean, and both population and sample standard deviation. The solver handles ax² + bx + c = 0 with real and complex roots, so x² + 2x + 5 = 0 returns −1 ± 2i. The base converter works between binary, octal, decimal and hex. The matrix tool does A + B, A × B and the determinant for 2×2 matrices.

Enter numbers separated by commas

Solve ax² + bx + c = 0

Convert a number between number bases

2×2 matrix operations

Matrix A

Matrix B

What Can the Real fx-115ES Plus Do That a Casio fx-115ES Online Tool Cannot?

Built-in constants and metric conversions at the press of a key
Textbook display with exact fractions and roots
Cubic and simultaneous equation solving
Complex numbers and vectors in dedicated modes
Matrices bigger than 2×2
Numeric derivatives and integrals, plus CALC and SOLVE

Is the fx-115ES Plus Allowed on Exams?

NCEES lists the Casio fx-115 line for the FE and PE exams. The SAT and ACT allow scientific calculators that are not CAS models. In South Africa, matric exam circulars have asked for approved, non-programmable, non-graphical calculators, so confirm the exact model with your school. ENEM in Brazil allows no personal calculator.

Casio fx-115ES Online or the Real One: Which Should You Use?

Use this page for homework, for checking a step, or when your calculator is not with you. Use the real fx-115ES Plus in exams and practise on it beforehand. Our buying guide compares it with the fx-991EX and TI-36X Pro, and the order of operations guide explains why brackets decide most wrong answers.

Is This Page Affiliated With Casio?

No. This is an independent calculator. Casio and fx-115ES are trademarks of Casio Computer Co., Ltd.

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Sources

Checked October 2026. Worked examples were calculated by hand and verified.