CalcWood: Smart online tools for woodworkers and DIYers
My vision and the main idea of the project
The goal of CalcWood is not to replace expensive and complex CAD software. I want to have a fast and extremely simple tool right in the workshop, which can also calculate demanding details. The whole project stands on these pillars:
- Maximum simplicity: No app installation, no downloading updates, and no annoying registration.
- Always at hand: It works right in the browser, whether you are on a PC in the office or on a mobile right at the workbench.
- Pro PDF outputs: At the end, you get a clear PDF report, including optimized cut lists with a yield of up to 95%.
- Smart QR code: Thanks to the QR code on the printed paper, you can return to the exact same project anytime with a single beep of your phone.
- Community-driven development: I develop and tune the tools directly based on real feedback from you in the field.
- A project for the whole world: The application is fully multilingual and currently runs in 6 world languages.
- The core forever free: Basic features will always be free for everyone, while expert PRO tools are for the most demanding users.
Note: The video shows the very first version of the calculator. Today, CalcWood can do much more, has a newer design, and includes additional tools.
From scribbled paper to an app
When working in the workshop, you are always calculating something. Drawer dimensions, slide clearances, exact slat spacing, cut lists... I always stood at the workbench with a pencil and a piece of paper, crossing out and rewriting.
It annoyed me how much time I was wasting and how easy it was to make a mistake that costs ruined material, time, and considerable money. I looked for a tool that would solve this simply and quickly. But nothing suited me 100%.
So I just had to program it myself.
And since I know from YouTube that millions of other DIYers and woodworkers face the exact same problem, I decided to gradually expand CalcWood and release it to the world for everyone.
How did this project actually start?
CalcWood is an online tool designed to help with the design and production of furniture. The idea is simple – you enter a few basic dimensions and the application calculates the rest.
The goal is not to replace workshop experience. Quite the opposite – to save time calculating and reduce the chance of making a mistake in dimensions and wasting material.
I often get asked what CalcWood is written in and if I programmed it all myself, or if "artificial intelligence generated it". Besides working with wood, I have been in the IT environment for over 20 years. I'm not a pure programmer, but I understand code and know how application architecture should work. Without this foundation, AI alone would be useless to me.
Development with an AI partner
I work in Microsoft VS Code, which is my main programming interface, and I don't hide the fact that AI was my partner. I use custom AI agents built on advanced models. In the end, it doesn't really matter whether you use ChatGPT, Claude, or Gemini. What matters is exactly how you define the programming bot (the so-called system prompt). Without strict rules, AI immediately gets lost in more complex code. Today it's a great worker for routine code, but it definitely doesn't work by just saying "generate a pro calculator".
- Weeks of daily work: Just the first calculator took me almost a month of tuning. It wasn't just about one calculation, but inventing the complete architecture.
- Step by step: The biggest challenge was the massive interconnectedness in JavaScript. Arrays have to monitor each other and change dynamically. The instructions for AI had to be extremely specific.
- Hundreds of trials and errors: I started with a few basic inputs. I calculated model examples manually, and only when the results matched in the code did I add more features and complex logic.
What can CalcWood actually do?
I originally started with just calculating drawers, but it gradually became a universal tool.
Drawers and Slides
You enter the cabinet dimensions, and the app calculates the exact dimensions of all parts. It supports Blum and classic slides, overlay and inset fronts. It handles individual drawer heights, smart gap calculation, and storage space maximization. It also includes a pro cut list with cutting optimization, ABS edge deduction, wood grain direction tracking, and much more.
Even Spacing
An extremely universal tool. Ideal for calculating fences, slats, posts, or grooves. Whatever you need to space evenly, this calculates it to the millimeter.
Shelf Sag
Find out if your shelf will sag under a load, not just immediately, but over time (shows approximate sag after 5 or 10 years).
Brilliant PDF reports with QR code
The big advantage is that the result doesn't just stay on the screen. Each calculator can generate a pro PDF report (or cut list). The PDF also contains a QR code – when you scan it in the workshop with your phone, it opens the exact configuration from which the document was created.
The core forever free, expert features for pros
You often ask if the whole thing will stay free. Let's be honest – the basic version of all calculators will always be free for everyone. I want to keep working with this community and make workshop tasks easier for every DIYer!
But I won't sugarcoat it. Developing and maintaining such a tool consumes a lot of time. The website must run on a reliable server, complex calculation logic needs constant testing, mobile views must be tuned, and flawless PDF report generation ensured. And for such a project to function long-term, grow, and remain independent, it simply has to be able to pay for its operation.
That's why you'll find features marked with the 
PRO badge in the calculators. These are expert settings mainly appreciated by professional woodworkers and skilled creators. Over time, I will charge a reasonable amount for these PRO features. It's not about getting rich, but covering the costs so I can keep maintaining the project, improving it, and creating new tools for the whole community.
A project for the whole world
CalcWood is currently available in 6 languages (CZ, EN, PL, DE, FR, ES). In the English version, it is also possible to switch units to the imperial system (inches), so the calculations make sense for users in the USA or Canada.
A quick IT window for the curious (and tech geeks)
- Vibe coding: A popular approach today where someone without programming knowledge just describes to AI what they want to create. AI generates the code, the app works at first glance, but the author doesn't really know how. The problem arises when you need to find a bug or add a complex feature – without knowing the basics, it all falls apart quickly.
- AI-assisted development: This is the path of CalcWood. I act as the main architect – designing the logic, file structure, security, and connections. I use AI as a fast partner (pair programming) that writes routine code for me based on my exact specifications.
- "Old School" Architecture: If a developer wanders in here, they will probably notice that CalcWood doesn't run on modern frameworks like React or Vue. I deliberately chose a classic and time-tested path (PHP 8, pure JavaScript, and CSS). For this type of tool, it is lightning fast, reliable, and doesn't unnecessarily complicate maintenance or hosting.
There are so many possible combinations of dimensions, overhangs, and hardware types that one person cannot simulate it 100%. That's why I released it as a Beta version and I'm fine-tuning any bugs on the fly based on real feedback from you.
Who is behind this?
I am Tomáš Horský. I don't call myself a YouTuber or just an IT guy – I am a creative creator. My background ranges from building early Wi-Fi networks on rooftops to IT administration, but my main goal has always been to create content that genuinely helps people.
Whether it's a woodworking video, detailed project plans, or this calculator, it's all about sharing knowledge and making your work easier.
You can find more of my projects on my YouTube channel or my personal website.
Want to support the CalcWood project?
CalcWood was created as an open project. If the tools help you in the workshop and save you time, you can support further development with any amount for a coffee.
Support the project here