Panel Cutting Algorithms: MaxRects, Guillotine and First Fit Simply Explained

Introduction

When you use a piece of software to plan your cuts, have you ever wondered what actually happens behind the scenes? How does the program decide where to place each piece on a sheet of plywood or MDF? The answer lies in panel cutting optimization algorithms — mathematical methods that calculate the most efficient arrangement of parts on a panel. Understanding the difference between MaxRects, Guillotine, and First Fit isn’t just academic. It directly affects how much material you waste, how long your job takes, and how much money stays in your pocket. This article breaks down each algorithm in plain English, with concrete analogies and a practical comparison.

What Is a Panel Cutting Algorithm, and Why Does It Matter?

A panel cutting algorithm is a set of rules that a program follows to decide how to arrange rectangular pieces on one or more full-size panels. The goal is always the same: fit as many pieces as possible on as few panels as possible, minimizing offcuts and wasted material.

This is harder than it sounds. Even with a modest cut list — say, 15 pieces of various sizes to cut from standard 2440 × 1220 mm sheets — the number of possible arrangements is astronomically large. No human could evaluate them all manually. That’s where algorithms come in.

The quality of the algorithm matters enormously. A poor arrangement might require three sheets where a better one needs only two. On a professional project, that’s a direct cost impact. On a DIY job, it’s the difference between buying one extra board or not. The right cut list software online doesn’t just display a grid — it runs smart calculations to protect your budget and your material.

MaxRects: The Tetris Master

MaxRects — short for Maximum Rectangles — is widely considered the most powerful general-purpose algorithm for 2D bin packing. Think of it like an expert Tetris player who doesn’t just react to the falling piece, but looks several moves ahead and constantly recalculates the best use of every remaining space.

Here’s how it works in principle. After each piece is placed on the sheet, the algorithm identifies all remaining free rectangles — every usable space left on the panel. It then evaluates each candidate piece against every available rectangle to find the placement that minimizes wasted space. This list of free rectangles is updated continuously as pieces are added.

The result is exceptional efficiency. MaxRects consistently achieves some of the highest utilization rates in benchmark tests, often placing 90–97% of usable area across a cut list. It handles irregular combinations of piece sizes well and adapts dynamically as the panel fills up.

The trade-off? It is computationally heavier than the alternatives. For very large cut lists with hundreds of pieces, it may take a moment longer to calculate. In practice, for woodworking applications, this difference is rarely noticeable.

Guillotine: The Industrial Saw’s Best Friend

The Guillotine algorithm takes its name from how it works — and how real panel saws actually operate. Every cut goes all the way across the remaining board, dividing it into exactly two rectangles. No partial cuts, no complex shapes. Just clean, straight lines from edge to edge.

Picture this: you have a full sheet of chipboard. You make a horizontal cut at 600 mm from the top. Now you have two pieces. You work on each sub-piece independently, making further guillotine cuts until you’ve extracted all your parts. That’s precisely the logic this algorithm follows.

This approach has a major practical advantage: it maps directly to how a panel saw or track saw is actually used in a workshop. The cutting sequence produced by a Guillotine algorithm can be followed step by step without rearranging material or making complicated partial passes. For industrial setups with automatic panel saws, this is not a preference — it’s a requirement.

The downside is reduced efficiency compared to MaxRects. Because every cut divides the full remaining area, you sometimes end up with awkward strips of waste that can’t be used. Utilization rates typically range from 80–90%, depending on the mix of part sizes.

First Fit: Fast, Simple, and Honest About Its Limits

First Fit is the algorithm equivalent of packing a suitcase in a hurry. You pick up each item in order and drop it into the first spot it fits. No looking ahead, no optimization — just fast placement using a simple rule.

In panel cutting terms, First Fit places each piece at the first available position on the current sheet (usually starting top-left), and moves to a new sheet only when the current one is full. It requires very little computing power and produces results almost instantly.

For small projects with pieces of similar dimensions, First Fit can perform surprisingly well. If you’re cutting 12 identical shelf panels from a single board, there’s not much optimization needed and First Fit gets the job done. However, for mixed cut lists with highly variable piece sizes, it tends to waste significantly more material than MaxRects or Guillotine.

Use First Fit when you want a rapid rough estimate, or when your pieces are simple and uniform. Think of it as a sanity check rather than a production-ready plan.

A Practical Comparison: Same Cut List, Three Algorithms

To make this concrete, consider a cut list for a simple workshop cabinet: 10 pieces ranging from 200 × 300 mm to 600 × 800 mm, to be cut from standard 2440 × 1220 mm MDF sheets.

In this example, First Fit requires an extra sheet — a real cost difference. Both Guillotine and MaxRects solve it in two sheets, but MaxRects wastes significantly less material within those two sheets. That leftover offcut from the MaxRects plan might be usable for a future project; the Guillotine offcut might not be.

This is why choosing the right algorithm for your situation matters. A professional furniture maker running dozens of projects a year should default to MaxRects. A cabinetmaker with a dedicated panel saw may prefer Guillotine for its practical cutting sequence. A hobbyist doing a one-off build can start with First Fit and refine if needed.

How Offcut Lets You Choose and Compare

Rather than locking you into a single approach, Offcut — a free online sheet cutting optimizer — integrates all three algorithms and lets you switch between them with a single click. You enter your panels and your parts, then select MaxRects, Guillotine, or First Fit and see the cutting layout update instantly.

This means you can run the same cut list through all three methods in under a minute and pick whichever result best suits your workshop setup and material budget. The tool also displays waste statistics for each result, so you can quantify the difference before making a decision.

Offcut exports your plan as a PDF with labeled pieces and cutting dimensions, and supports JSON and CSV import/export for integration with your existing workflow. It runs directly in your browser — no installation, no subscription, no barriers.

Whether you’re a joinery student learning how cutting plans work, or an experienced woodworker looking to reduce wood waste on a complex job, having algorithm choice built into your cutting plan calculator is a genuine competitive advantage.

Conclusion

MaxRects, Guillotine, and First Fit each have a legitimate place in panel cutting optimization. Understanding their differences helps you make better decisions — not just about which software to use, but about how to approach each project. MaxRects gives you the best material efficiency. Guillotine gives you a cutting sequence that works on real machines. First Fit gives you speed when you just need a quick answer.

The smartest move is to have access to all three. Try them on your next project with Offcut, the free online cutting plan calculator that puts algorithm choice in your hands — and shows you exactly how much wood you’ll save.