If you have ever changed one dimension in a CAD model and watched the entire design update automatically — that is parametric design at work. It is one of the most powerful concepts in modern engineering and product design, and Fusion 360 is built around it from the ground up. This guide explains everything you need to know to start designing parametrically in Fusion 360 — from the basic concepts to practical techniques you can use right away. What is Parametric Design? Parametric design means building your 3D model around parameters — numbers, dimensions and relationships — rather than fixed, unchangeable geometry. In a traditional CAD workflow, if you want to change the width of a bracket from 50mm to 60mm, you might have to delete and redraw several features. In parametric design, you just change one number and the entire model updates automatically. This makes your designs faster to modify, easier to reuse and far more flexible across different project requirements. Why Parametric Design Matters In the real world, designs change constantly. A client asks for a slightly wider bracket. A supplier changes a standard screw size. A motor mount needs to fit a different motor. With parametric design, these changes take seconds. Without it, they can take hours of manual redrawing. For engineers, makers and product designers, parametric design is not just a convenience — it is how professional work gets done efficiently. How Fusion 360 Handles Parametric Design Fusion 360 uses a feature-based, history-driven parametric system. Every operation you perform — sketches, extrudes, fillets, holes — is recorded in a timeline at the bottom of the screen. When you change a parameter, Fusion 360 replays the entire timeline with the new value, rebuilding your model automatically from the ground up. This timeline-based approach gives you complete control over your design history and makes editing at any stage possible. Parameters in Fusion 360 The heart of parametric design in Fusion 360 is the Parameters panel. You can access it by going to Modify and clicking Change Parameters. Here you can create named parameters like these: platewidth = 60mm plateheight = 40mm boltdiameter = 3mm wallthickness = 5mm Once created, you can use these names directly in your sketch dimensions instead of typing fixed numbers. Type platewidth instead of 60 and the sketch dimension is now linked to that parameter. Change platewidth from 60 to 80 in the Parameters panel and every part of your model that references it updates instantly. Building Your First Parametric Model The best way to understand parametric design is to build something simple with it. Here is a step by step walkthrough of a basic parametric bracket. Step 1 — Define Your Parameters Before drawing anything, open the Parameters panel and define your key dimensions as named parameters. For a simple bracket you might define: width = 80mm height = 50mm thickness = 5mm holediameter = 4mm Step 2 — Create a Sketch Using Parameters Start a new sketch on the XY plane. Instead of typing fixed dimensions when constraining your sketch lines, type your parameter names instead. Set your rectangle width to width and height to height. Now your sketch is linked to your parameters. Step 3 — Extrude Using a Parameter Press E to open Extrude. In the distance field, type thickness instead of a fixed number. Your extrusion depth is now parametric. Step 4 — Add Holes Using Parameters Sketch circles for your bolt holes. Set each circle diameter to holediameter. Extrude them as a Cut operation all the way through. Step 5 — Test Your Parameters Now open the Parameters panel and change width from 80 to 100. Click OK and watch your entire bracket update automatically — wider plate, holes repositioned, everything in proportion. That is parametric design in action. Sketch Constraints — The Foundation Parameters alone are not enough for true parametric design. You also need sketch constraints — geometric rules that define how your sketch elements relate to each other. Fusion 360 supports many constraints: Horizontal and Vertical force lines to stay perfectly straight. Coincident connects two points together so they always stay joined. Parallel keeps two lines always running in the same direction. Perpendicular keeps two lines always at exactly 90 degrees to each other. Equal makes two lines or circles always the same size. Symmetric keeps two elements always mirrored around a center line. The more constraints you apply, the more predictable and reliable your model will be when parameters change. Fully Constrained vs Under-Constrained Sketches A fully constrained sketch is one where every line and point is locked in place by either a dimension or a constraint. In Fusion 360, fully constrained sketch lines turn black. An under-constrained sketch has some elements that are free to move. These stay blue in Fusion 360. For parametric design to work reliably, your sketches should always be fully constrained.