> ## Documentation Index
> Fetch the complete documentation index at: https://calcs.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Your First Calculation: Area Calculator

> Build an area calculator (length × width) in Calcs Builder — video walkthrough + key steps

Create a simple **area calculator** (rectangle area = length × width). This is the fastest way to learn the Calcs Builder basics:

**Inputs → Equation → Output → Preview**

<Tip>
  Want a fully written, click-by-click tutorial? Start with [Quick Start: Pythagoras Theorem](/calcs_builder/quick_start_guide) and come back here for a second example.
</Tip>

***

## What you’ll build

A calculator that takes:

* **Length (L)** in **ft**
* **Width (W)** in **ft**

…and outputs:

* **Area (A)** in **ft²**

Using the equation:

`A = L × W`

***

## Video walkthrough

<iframe src="https://fast.wistia.com/embed/medias/5egy9v102m" title="How to create an area calculator with Calcs Builder" className="w-full h-96 rounded-xl" />

<details>
  <summary>Video transcript</summary>

  Create a new calculator, name it **Area calculator**, and set a **calculator code** (this is the unique identifier used for sharing and URLs).

  Next, define the inputs:

  * Add an input for **Length (L)** and set units to **feet (ft)**.
  * Add an input for **Width (W)** and set units to **feet (ft)**.

  Then create a calculation section:

  * Add an **Equation** widget.
  * Define the output variable **Area (A)** and set its units to **ft²**.
  * Enter the formula `L * W`.

  Finally, open **Preview**, enter values for **L** and **W**, and confirm the area updates correctly in **ft²**.
</details>

***

## Build steps (quick reference)

If you want to follow along while watching, use this checklist.

<Steps>
  <Step title="Create a new calculator">
    In **Calculator Builder**, click **Create a new calculator**, name it **Area Calculator**, and set a short, unique **calculator code** (e.g., `area-calculator`).
  </Step>

  <Step title="Add inputs">
    Add two **Input** widgets:

    * **Length**: RefID `L`, Symbol `L`, Units `ft`
    * **Width**: RefID `W`, Symbol `W`, Units `ft`
  </Step>

  <Step title="Add the equation">
    Add an **Equation** widget:

    * Output variable: **Area** with RefID `A`, Symbol `A`, Units `ft^2`
    * Formula:
      ```
      L * W
      ```
  </Step>

  <Step title="Preview and test">
    Click **Preview** and test a couple values:

    * `L = 10`, `W = 2` → `A = 20 ft²`
    * `L = 3.5`, `W = 4` → `A = 14 ft²`
  </Step>
</Steps>

***

## Common gotchas

* **Units:** If inputs are in `ft`, the output should be `ft²` (area is length squared).
* **Variable naming:** Equations reference **RefID**, so the formula must match exactly (`L * W`, not `Length * Width` unless those are your RefIDs).
* **Consistency:** Keep units consistent across related inputs to avoid confusing results.

***

## Key takeaways

This example reinforces the essential Calcs Builder workflow:

* **Name + Code** — the calculator code is how your calculator is identified and shared.
* **Inputs** — gather the user data (length and width).
* **Equation** — define the math (`L * W`).
* **Preview** — validate quickly with sample numbers.

***

## Next steps

<CardGroup cols={2}>
  <Card title="Quick Start: Pythagoras Theorem" href="/calcs_builder/quick_start_guide" icon="rocket">
    Written step-by-step guide with RefID & Symbol tips
  </Card>

  <Card title="Widget Overview" href="/calcs_builder/widgets/overview" icon="puzzle-piece">
    Explore all available widgets
  </Card>

  <Card title="Template Features" href="/calcs_builder/template_features" icon="book">
    Advanced template options
  </Card>

  <Card title="Common Workflows" href="/calcs_builder/common_workflows" icon="arrows-rotate">
    Real-world examples
  </Card>
</CardGroup>

***

## Need help?

* [Troubleshooting](/calcs_builder/common_errors)
* [Best Practices](/calcs_builder/best_practices)
* **Support** — [support@calcs.com](mailto:support@calcs.com)