123Trig

Your Trigonometry Pal

Learn and calculate areas, volumes, and perimeters of geometric figures in seconds.
123Trig is a free, multilingual visual tool — ideal for middle and high school students.

Little Intro: Geometry isn’t just about shapes on paper — it’s the secret behind so many everyday things! From figuring out how many tiles fit in your bathroom, to how much paint fills your walls, or even picking the right air conditioner for your room — it’s all geometry. Once you see it, you can’t unsee it!

123Trig is a simple, multilingual calculator built for students. It helps you learn and compute geometric figures quickly, without distractions.

Select a shape, input dimensions, and get instant results for perimeter, area, or volume. All formulas are shown visually and translated to your language.

123Trig es una calculadora visual y multilingüe pensada para estudiantes. Ayuda a aprender y resolver figuras geométricas de forma rápida y sin distracciones.

Selecciona una figura, ingresa sus dimensiones, y obtén al instante el perímetro, área o volumen. Todas las fórmulas se muestran de forma visual y en tu idioma.

123Trig est une calculatrice simple et multilingue conçue pour les élèves. Elle permet de comprendre et résoudre des figures géométriques rapidement, sans distractions.

Choisissez une forme, entrez ses dimensions, et obtenez instantanément le périmètre, la surface ou le volume. Toutes les formules sont affichées visuellement et traduites dans votre langue.

123Trig é uma calculadora simples e multilíngue feita para estudantes. Ela ajuda a aprender e resolver figuras geométricas de forma rápida e sem distrações.

Selecione uma forma, insira as dimensões e veja instantaneamente o perímetro, área ou volume. Todas as fórmulas são mostradas visualmente no seu idioma.

123Trig ist ein einfaches, mehrsprachiges Tool für Schüler. Es hilft dir, geometrische Figuren schnell und ohne Ablenkung zu verstehen und zu berechnen.

Wähle eine Form, gib die Maße ein und erhalte sofort Umfang, Fläche oder Volumen. Alle Formeln werden visuell dargestellt und übersetzt.

123Trig è una calcolatrice semplice e multilingue pensata per gli studenti. Aiuta a comprendere e risolvere figure geometriche in modo rapido e senza distrazioni.

Seleziona una figura, inserisci le dimensioni e ottieni subito perimetro, area o volume. Tutte le formule sono mostrate visivamente e tradotte nella tua lingua.

Definitions
Perimeter is the total length around a shape. It’s straightforward for polygons.
Area is the space inside a 2D shape. Each figure has a specific formula.
Volume measures how much space a 3D shape occupies, in cubic units.
Surface area is the total area of all faces of a 3D object.
🔎 Select a shape below and enter its dimensions to get instant results. Calculations update automatically in your language.
You can also navigate using the top menu.

🟪 The 2D Universe — or Flatland!

Welcome to Flatland — a world with only length and width, no depth allowed! It’s where geometry begins: the realm of drawings, tiles, and blueprints.

Square
A square has four equal sides and right angles. Use it to calculate area and perimeter easily.
a
Formulas
= 4a = a²
Results
Rhombus
A rhombus has four equal sides but tilted angles. It often looks like a diamond in patterns and kites.
d₁ d₂ a
Formulas
= 4 x a = b x h
Results
💡 A rhombus is just a parallelogram with all sides equal. If you know the height, the area is a × h.
Rectangle
A rectangle has opposite sides equal. Quickly find its area and perimeter with two sides.
l w
Formulas
= 2(l + w) = l × w
Results
Parellelogram
A parallelogram has opposite sides equal and parallel — like a pushed-over rectangle.
b s h
Formulas
= 2 x (b + a) = b x h
Results
Triangle
A triangle has three sides. With base and height, you can get its area fast.
b h
Formulas
not implemented = (b × h) / 2
Results
Right Triangle
A right triangle has one 90° angle. It’s the shape behind Pythagoras’ theorem and countless designs.
b a=h c
=>
Formulas
= (b × h) / 2 = a + b + c Pythagoras: c² = a² + b² ->: c = √(a² + b²)
Results
💡 If there’s ONE thing to remember forever, it’s Pythagoras’ theorem.
Isosceles Triangle
An isosceles triangle has two equal sides and a balanced look — symmetry made simple.
b h a a
=>
Formulas
= b + 2(a) a = √((b/2)² + h²) (Pythagoras: h² + (b/2)²=a²) = (b × h) / 2
Results
💡 An isosceles triangle can be seen as two right triangles back to back.
Equilateral Triangle
An equilateral triangle has all sides and angles equal — pure geometric harmony.
a a a h
=>
Formulas
= 3a h = (√3 / 2) × a Pythagoras: h² + (a/2)²=a² = (√3 / 4) × a²
Results
💡 Same spirit: an equilateral triangle relates neatly to right-triangle reasoning. Pythagoras does the heavy lifting; height isn’t even needed if you know a.
Pentagon
A pentagon has five equal sides and angles — a first step into regular polygons.
a ap
Formulas
= 5a = (Perimeter × ap)/2
Results
💡 Everything looks like a combination of triangles if you look closely. A regular pentagon is 5 isosceles triangles. Its area is 5 times the area of one.
Hexagon
A hexagon has six equal sides — nature’s favorite shape in honeycombs and crystals.
a ap
Formulas
= 6a = ((3√3) / 2) × a² or = (Perimeter × ap)/2
Results
💡 A regular hexagon is 6 equilateral triangles, so its area is 6 × the equilateral-triangle formula. You don’t need the apothem, but you can use it if you have it.
Regular n-gon
Regular polygons with many sides start to look like circles — the more sides, the smoother.
ap a r
Formulas
= n × a = n x ( a x ap ) /2 or = (Perimeter × ap)/2 Pythagoras: r² = (a/2)² + ap² -> ap² = r² - (a/2)²
Results
💡 All regular polygons are just a bunch of isosceles triangles — hence the similar formulas. As n increases and a decreases, the figure resembles a circle. The area idea aligns: perimeter × radius (apothem).
Circle
A circle is a 2D shape with a constant radius. Compute its area and perimeter in one step.
r
Formulas
= 2πr = πr²
Results
💡 Here it is — the “infinigon.”
Ellipse
A stretched circle (oval) defined by two semi-axes.
a b
Formulas
= π x a x b = approximation out of scope
Results
💡 The ellipse is tricky: its perimeter has no simple closed form — we use approximations. (Yes, this still interests mathematicians!)

🌐 The 3D Universe — Space Awaits!

Step into the world of depth, height, and width — where geometry comes alive! Explore cubes, prisms, cylinders, cones, and spheres.

Cube
A cube is a 3D shape with six equal square faces. It lets you compute volume and surface area.
a a a
Formulas
= 6a² = a³
Results
Rectangular Prism
A rectangular prism is a box-shaped 3D object. Use it to find surface area and volume.
l H w
Formulas
= 2(l*w + l*H + w*H) = l × w × H
Results
Generic Straight Prism
A straigh prism with any polygonal base — straight means "super regular" here.
H
Formulas
V = A × H S = 2A + P × H
Results
💡 A prism’s volume depends only on base area and height. For surface area, add the two base areas and the lateral area (perimeter × h).
Key rule: decomposition — slice hard shapes into easy pieces.
Oblique Prism
A prism where the sides are tilted. The base is the same, but the height is measured vertically.
H
Formulas
S = 2A + Area of Sides V = A × H
Results
Tilt a prism and the volume formula stays the same. Surface area gets harder: the sides become parallelograms; compute each and sum with the two bases."
Triangular Pyramid
A triangular pyramid has a triangular base and three triangular faces. You can calculate its volume easily.
H h b
Formulas
= Not available = (((b x h)/2) x H)/3 = (b × h × H) / 6
Results
💡 The volume of a triangular pyramid is the area of its base times its height, all divided by 3. Why? Because three identical pyramids can fit into a triangular prism.
Generic Pyramid
A pyramid built from any polygonal base. Just enter the base area and the height.
H
Formulas
V = (A × H) / 3
Results
💡 Every pyramid’s volume equals one-third of the prism with the same base and height.
Generic Oblique Pyramid
A pyramid whose apex is offset from the base’s center — here with a flattened star base.
H
Formulas
S = A + Area of all sides V = (A × H) / 3
Results
💡 When the apex shifts sideways, the pyramid is oblique — the volume formula stays the same, but surface area is harder: each side is a triangle; compute each and sum with the base.
Cylinder
A cylinder has two circular faces and a height. Get surface area and volume with simple inputs.
r H
Formulas
= 2πr² + 2πrH = πr²H
Results
Cone
A cone has a circular base and tapers to a point. Compute area and volume with radius and height.
r h
Formulas
= πr² + πr√(r² + H²) = (1/3)πr²H
Results
💡 So… are cones just fancy pyramids?
Sphere
A sphere is a perfectly round 3D shape. Use its radius to get surface area and volume.
r
Formulas
= 4πr² = (4/3)πr³
Results