The Math Behind Welding: A Welder\’s Guide

Did you know math is a skill that a welder must master? Welders must know how to measure materials and calculate cutting force, understand how heat can warp metal and weld seams together, read scales used on blueprints, and determine the exact amount of materials to use. A welder must be familiar with fractions, decimals, geometry, formulas and trigonometry. With these math skills, a welder can make strong welds regardless of the type of material used. However, knowing the melting point of a metal is only one useful math skill in the welder’s arsenal.

Reading Blueprints

Blueprints are 2-dimensional architectural design drawings that reveal a structural plan to scale and specifies the material required. Because accurate blueprint readings require a thorough understanding of such math concepts as fractions and decimals, a welder is expected to possess strong math skills. Welders must know what fraction of scale is being used for the blueprints—common architectural scales, for instance, use ¼ of an inch to represent the length of one foot—this way the welder can properly measure out project sizes, cut pipe, and weld seams.

The basic blueprint will have three common perspectives including plan, elevation and section. The plan perspective is a bird’s-eye view of the structure planned. This perspective allows mapping of width and length. The elevation perspective refers to a side-view of the structure. An elevation map allows the welder to plan for height dimensions. Lastly, the section perspective can be described as a cut through and helps the welder understand the inner workings of the structure. Along the horizontal and vertical edges of a blueprint, welders will often find a grid system including numbers and letters. This grid system allows a specific point on the drawing to be referenced at any time.


Geometry, a branch of math dealing with the basic measurement, properties, and relationships of points, lines, angles, surfaces and solids, is used by welders to work out such measurements as angles, radius, volume, diameter and circumference. These measurements help them form accurate joints.

Point – a location or position in space or on a plane. With reference from an origin, each point on a line has a specific location.

Surface – 2D or 3D construction in space or a plane with no thickness.

Angles – The space between two intersecting lines or surfaces at the point they meet. The two lines that join to form an angle are referred to as the arms. The common point where the two lines meet is the vertex.

Radius – A straight line from the center to the circumference of a circle or sphere. To calculate the radius, divide the diameter by two.

Volume – The amount of space a substance or object occupies. To calculate the volume, multiply the length by the width by the height.

Diameter – A straight line that passes from side to side through the center of a circle or sphere. The diameter is calculated by dividing the circumference by pi (3.14).

Circumference – The distance around a circle. The circumference can be calculated as twice the radius times pi or the diameter of the circle times pi.

Formulas in Welding

Welders rely on basic mathematical formulas to carry out tasks, using formulas for squared and cubed calculations, for shapes and volume. A welder may need to determine the pressure and volume of gases. They will need to understand proportions using functions and equations. Formulas that calculate how temperature will change, used for different types of metals with different melting points. Understanding the probability of the targeted versus the actual welding outcome is also important.


Trigonometry is a branch of math that deals with the relationship of the sides and angles of triangles and the relevant functions of angles. A welder will need to understand the math behind sine, cosine and tangent. This will help the welder both calculate degrees for accurate angles as well as identify the strength of a weld. Given a right triangle, welders can find the sine, cosine or tangent of either of the non-90-degree angles.

Sine – Equal to the ratio of the side opposite a given angle to the hypotenuse.

Cosine – Equal to the ratio of the side adjacent to an acute angle to the hypotenuse.

Tangent – A straight line or plane that touches a curved surface at a point and does not extend across it at that point.

Final Thoughts

Needless to say, math is critical in the field of welding and proves itself to be very necessary for a welder to do their job successfully. Knowing whole numbers, fractions, decimal conversion, geometry, formulas, trigonometry, and other math skills make a welder invaluable to their team. Having a strong handle on math can make you indispensable and secure your position on the infrastructure team.

Are you interested in becoming a welder? Ready to put your welder\’s Math knowledge to the test? The Welding Technology Program at MIAT College of Technology provides the hands-on training, practical experience and industry support it takes to pursue a rewarding technical career. Classes are interactive and led by dedicated instructors with years of experience working with welding equipment in a professional setting. You’ll get the one-on-one attention and personal support to pick up new skills quickly and the first-hand technical knowledge to feel confident entering the workforce.

To learn more about the Welding programs and explore if MIAT is right for you, fill out the form on this page. Contact us if you are interested in becoming a welding technician today.

MIAT College of Technology is accredited by the Accrediting Commission of Career Schools and Colleges (ACCSC).