How to Use Donut Calculator
The Donut Calculator turns a tedious planning task into a few clicks. Each input maps directly to a concrete recommendation, and the result panel updates as you adjust the form.
- Choose 2D annulus mode for area, or 3D torus mode for volume and surface area.
- Enter the outer radius (or major radius for torus) and the inner / tube radius.
- Pick a length unit and decimal precision.
- Read the area or volume/surface area, plus the helpful diameter rows and the step calculation.
Formula & Theory — Donut Calculator
Under the hood, the Donut Calculator uses these formulas:
Annulus area A = π(R² − r²)
Torus volume V = 2π² · R · r²
Torus surface S = 4π² · R · r
where R = major radius (outer), r = tube / inner radiusEvery row in the result is derived from these formulas, so you can audit the recommendation, swap units, or rebuild the same numbers in a spreadsheet if you want to extend the model. The Donut Calculator keeps the math transparent so you stay in control of your shopping or cooking decisions.
Use Cases for Donut Calculator
The Donut Calculator is built for real-world planning. Common scenarios include:
- Math students learning the geometry of annular regions and toroidal solids.
- Bakers and pastry chefs estimating the dough volume for a tray of donuts.
- 3D modellers sanity-checking torus dimensions before exporting a model.
- Engineers verifying o-ring or seal volumes for industrial design.
- Teachers building intuitive worked examples for π and rotational solids.
Whether you’re organising a party, designing a recipe, or simply trying to avoid waste, the Donut Calculator delivers an instantly actionable plan that scales from one guest to dozens.