Logarithm Calculator — log_b(x), ln and log10
Calculate the logarithm to any base, the natural logarithm (ln) and the common logarithm (log10). Free logarithm calculator with change of base formula.
Math calculators
Quick percentage and arithmetic calculations. Pick a calculator below.
Roman Numerals Calculator — Roman-Arabic Converter
Convert Arabic numbers to Roman numerals and back. Roman numeral converter with subtractive notation, range 1–3999. Free online calculator.
Arithmetic Sequence Calculator — nth Term and Sum
Find the nth term and sum of an arithmetic sequence from the first term and common difference. Formulas a_n = a₁ + (n−1)·r and Sₙ. Free math calculator.
Popular Percentage calculator
Calculate the percentage of a number, a percentage increase and a percentage decrease. Free percentage calculator.
Fraction Calculator
Calculate addition, subtraction, multiplication and division of fractions online. Result as simplified fraction and decimal. Free.
Average Calculator
Calculate arithmetic mean, median, minimum and maximum from numbers. Free online average calculator.
GCD and LCM Calculator
Calculate GCD (greatest common divisor) and LCM (least common multiple) of two numbers. Free online calculator.
Quadratic Equation Calculator
Solve quadratic equation ax²+bx+c=0. Calculate discriminant and roots online for free.
Area calculator — geometric shapes
Calculate the area of geometric shapes: rectangle, square, triangle, circle, trapezoid, rhombus. Free online geometry calculator.
Popular Area of Geometric Shapes Calculator
Calculate the area and perimeter of geometric shapes online: square, rectangle, triangle, circle, trapezoid, rhombus, regular hexagon and ellipse.
Roots and powers calculator
Calculate square root, cube root, nth root or any power of a number. Free math calculator — no signup required, instant results.
Factorial, combinations and permutations calculator
Calculate factorial n!, combinations C(n,k) and permutations P(n,k) online. Free combinatorics calculator — useful for math, stats and probability.
Rounding calculator
Round any number to 1, 2 or 3 decimal places, to the nearest whole, ten, hundred or thousand. Free online rounding calculator with rounding error.
Number base converter
Convert numbers between binary, octal, decimal and hexadecimal. Free online number base calculator — instant conversion, no signup required.
Popular Triangle Calculator
Calculate triangle area, perimeter and angles using Heron's formula. Enter three sides or two sides and an angle — free geometry calculator online.
Popular Compound Interest Calculator
Calculate final capital with compound interest. Enter annual rate, term and compounding frequency — free investment calculator with PLN result online.
Percentage Calculator
Calculate what percent A is of B, find X% of a number, percentage change or add a percent to a value. Fast percentage calculator online, free.
Prime Number Calculator
Check if a number is prime, find the next prime number, or factorize a number into prime factors. Instant result online, no registration needed.
Linear Equation Calculator
Solve linear equations of the form ax + b = c online. Enter coefficients a, b and c to instantly find x with step-by-step verification.
Trigonometry Calculator
Online trigonometry calculator — compute sin, cos, tan, arcsin, arccos, arctan for any angle in degrees or radians. Fast, accurate, free.
Geometric Sequence Calculator
Calculate the nth term, partial sum, and infinite sum of a geometric sequence online. Fast calculator with formulas and examples for students and teachers.
2x2 Matrix Calculator
Calculate the result of 2x2 matrix operations: addition, subtraction and multiplication. Also check the determinants of both matrices.
Logarithm Calculator
Calculate the logarithm of any number with a custom base, natural logarithm (ln) and common logarithm (log10). Fast online logarithm calculator.
Volume of Geometric Solids Calculator
Calculate the volume of geometric solids online: cube, cuboid, sphere, cylinder, cone, square pyramid and triangular prism. Instant results with formulas and examples.
Combinatorics Calculator
Calculate permutations P(n), combinations C(n,k), arrangements V(n,k) and their with-repetition variants. Formulas and examples. Free online combinatorics calculator.
Polynomial Derivative Calculator
Calculate the derivative of a polynomial up to degree 4 using the power rule. Enter coefficients, optionally provide x, and get the derivative formula and numeric value.
Triangle Area Calculator
Calculate the area of a triangle from the formula half times base times height. Enter base and height — instant result. Heron formula for three sides.
Cylinder Volume Calculator
Compute cylinder volume with V = pi*r^2*h. Enter radius and height to get volume in cm3 and litres plus total surface area.
Everyday math
Percentages are one of the most used mathematical concepts in everyday life — from calculating discounts to analysing growth. Our calculators give you instant results without memorising formulas.
Frequently asked questions
How do I calculate a percentage of a number?
Formula: result = number × percent / 100. E.g. 15% of 200 = 30.
How do I find what percent one number is of another?
Percent = (part / whole) × 100. E.g. 30 out of 200 is 15%.
How do I calculate a percentage increase?
New value = old × (1 + percent/100). E.g. 200 + 15% = 230.
How do I calculate a percentage decrease (discount)?
New value = old × (1 − percent/100). E.g. 200 − 15% = 170.
How do I calculate percentage change between two numbers?
Change % = ((new − old) / old) × 100.
What is the difference between a 100% increase and doubling?
A 100% increase means doubling — they are the same.
How do I reverse a percentage — find the original value?
Original = result / (percent/100). E.g. if 30 is 15%, original = 30/0.15 = 200.
How do I calculate a price after a discount?
Price after discount = price × (1 − discount/100). E.g. PLN 200 with 15% off = PLN 170.
Do the calculators handle fractional percentages?
Yes, e.g. 12.5% works fine.
Are the results accurate?
Yes — exact math rounded to 2 decimal places.