Engineering Mathematics Calculators

Complex number, phasor, trig, statistics, equations, matrix, vector, geometry, probability, combinations, binomial and ratio calculators.

Electrical engineering uses mathematics that a general calculator handles badly: complex numbers for impedance and phasors, angles in degrees, and results that must be read in both rectangular and polar form. This division collects those tools for engineers, technicians and students. The complex number calculator adds, subtracts, multiplies and divides two complex numbers and converts one between rectangular (a + jb) and polar (magnitude and angle) form, showing each step so you can check a hand calculation. The phasor sum calculator adds or subtracts up to three phasors given as magnitude and angle, such as phase voltages or branch currents, and returns the resultant. The trigonometry calculator gives sin, cos, tan and the reciprocal functions of an angle in degrees or radians. The percentage error calculator compares a reading with its true value and shows whether it is high or low. The simultaneous equations solver finds two or three unknowns from circuit loop equations, and the linear interpolation calculator reads a value between two known points, such as a 4 to 20 mA signal scaled to its range. The matrix calculator finds the determinant, trace and inverse of a 2 × 2 or 3 × 3 matrix, and the vector calculator gives the lengths, dot product, angle and cross product of two three-dimensional vectors. The linear regression calculator fits a least-squares line through up to 10 measured points and gives its slope, intercept and r². The Pythagorean theorem calculator finds the missing side of a right triangle, the triangle calculator gives the angles and area from three sides, and the circle calculator converts between radius, diameter, circumference and area. The area calculator covers eight flat shapes, from a rectangle to a regular polygon, and the volume and surface area calculator covers the box, cylinder, sphere, cone and pipe, which is what you need for tank capacities and coating areas. The slope calculator turns two points into a gradient, grade and angle, which suits cable trench falls and conduit runs, and the distance calculator gives the straight-line distance and midpoint between two points in 2D or 3D. The probability calculator gives the chance of both, either or neither of two events, with independent, mutually exclusive or overlapping events, and the chance that something happens at least once over repeated trials, which is the arithmetic behind redundancy and fault-chance estimates. The permutations and combinations calculator counts the ways of choosing r items from n, in order or not, with or without repetition, and the binomial distribution calculator gives the chance of exactly, at most or at least k successes in n independent trials, which is how a k-out-of-n redundant system or a row of lamps is assessed.

Where to start

Complex Numbers (Rectangular and Polar): Add, subtract, multiply and divide complex numbers, and convert between rectangular and polar form.
Phasor Sum and Difference (Polar Inputs): Add or subtract up to three phasors given as magnitude and angle.
Percentage Error: Error, relative error and percentage error of a reading against its true value.
Mean, Median and Mode: Mean, median, mode and range of up to 12 readings.
Standard Deviation and Variance: Sample and population standard deviation, variance and standard error of up to 12 readings.
Quadratic Equation Solver: Real or complex roots, discriminant and vertex of ax² + bx + c = 0.
Logarithm Calculator: Logarithm to any base, with common, natural and binary logarithms.
Exponent and Root Calculator: Any power, and square, cube and nth roots, with checks for invalid cases.
Percentage Calculator: A% of B, percentage change, and B increased or decreased by a percentage.
Ratio Calculator: Simplify a ratio, find the shares, and solve a proportion.
Rounding and Significant Figures: Round to decimal places or significant figures, up, down or truncated.
Fraction Calculator: Add, subtract, multiply and divide fractions; simplified, mixed and decimal results.
Simultaneous Equations Solver: Solve two or three linear equations, such as circuit loop equations, with a check by substitution.
Linear Interpolation Calculator: Find y at x, or x at y, on the line through two known points, with the slope.
Pythagorean Theorem (Right Triangle) Calculator: Missing side, angles and area of a right triangle from any two sides.
Triangle Calculator (Three Sides): Angles, area and circle radii of a triangle from its three sides.
Circle Calculator (Radius, Diameter, Circumference, Area): Radius, diameter, circumference and area of a circle from any one of them.
Area Calculator (Rectangle, Trapezoid, Ellipse, Sector, Ring, Polygon): Area and perimeter of a rectangle, triangle, trapezoid, parallelogram, ellipse, sector, ring or regular polygon.
Volume and Surface Area Calculator (Box, Cylinder, Sphere, Cone, Pipe): Volume and surface area of a box, cylinder, sphere, cone or pipe.
Slope Calculator (Gradient, Grade and Angle from Two Points): Slope, grade, angle and 1-in-N gradient of the line through two points.
Distance Calculator (Between Two Points, 2D or 3D): Distance, midpoint and angle between two points in 2D or 3D.
Probability Calculator (Two Events, A and B, and Repeated Trials): Chance of both, either or neither of two events, conditional probability, and at-least-once over repeated trials.
Linear Regression (Line of Best Fit): Least-squares line through up to 10 points: slope, intercept, r² and a prediction.
Matrix Calculator (2×2 and 3×3): Determinant, trace and inverse of a 2 × 2 or 3 × 3 matrix, with a check.
Vector Calculator (3D): Lengths, dot product, angle, cross product and component along B for two 3D vectors.
Trigonometry (Sin, Cos, Tan): Sine, cosine, tangent and their reciprocals for an angle in degrees or radians.
Permutations and Combinations Calculator (nPr, nCr): Permutations and combinations of r from n, with and without repetition, and n factorial.
Binomial Distribution Calculator (Exactly k, At Most, At Least): Chance of exactly, at most or at least k successes in n independent trials, with mean and spread.
AC Ohm's Law (Phasors): Voltage, current and impedance as phasors, with the power triangle.
Series RLC Impedance: Impedance, phase angle and power factor of a series R-L-C circuit.

All 28 calculators in this category