A rectangular prism is one of the most common 3D shapes, found everywhere from shipping boxes and rooms to books and aquariums . Calculating its properties is a fundamental task in geometry, but doing it manually is time-consuming and prone to error.

Your Rectangular Prism Calculator is a dynamic web tool that eliminates this hassle. It goes beyond basic volume calculations, allowing users to find multiple unknown properties like volume, surface area, and diagonal, even when starting with different combinations of known values . This flexibility, combined with a clean, professional interface, makes it an invaluable resource for students, teachers, DIY enthusiasts, and professionals in fields like construction and design.

How to Use the Calculator

1. Select Your Calculation Type
   Choose the scenario that matches the values you already know from the dropdown menu. For example, if you know the total surface area, length, and width, select “Calculate h, V, d | Given S, l, w.”
2. Enter Your Known Values
3. Configure Units and Precision (Optional)
   • Select your unit of measurement (e.g., cm, m, ft) from the “Units” dropdown. The results will reflect the square (for area) and cubic (for volume) versions of this unit.
   • Choose the number of significant figures for your answer or leave it on “auto.”
4. Calculate and Review

The Formulas Behind the Calculations

Your calculator leverages core geometric formulas to deliver instant results. Here are the key equations it uses :

The tool also uses advanced algebraic manipulations for its alternative scenarios. For instance, if the total surface area (S), length (l), and width (w) are known, it rearranges the surface area formula to solve for height: h = (S - 2lw) / (2l + 2w) .