Scientific precision, live in your browser
表面積計算機
Instant formulas, live results, and step-by-step breakdowns for every 3D shape.
Choose by shape
計算機を選ぶ
Each calculator shows the formula, intermediate values, units, and references so results are easy to check.
球表面積計算機
SA = 4πr²立方体表面積計算機
SA = 6a²円柱表面積計算機
SA = 2πr(r + h)円すい表面積計算機
SA = πr(r + √(r² + h²))直方体表面積計算機
SA = 2lw + 2lh + 2wh三角柱表面積計算機
SA = PL + 2B角すい表面積計算機
SA = base + lateral faces楕円体表面積計算機
SA ≈ 4π[((a^1.6b^1.6 + a^1.6c^1.6 + b^1.6c^1.6) / 3)]^(1/1.6)カプセル表面積計算機
SA = 4πr² + 2πrhトーラス表面積計算機
SA = 4π²Rr円すい台表面積計算機
SA = π(R² + r²) + π(R + r)√((R - r)² + h²)球冠表面積計算機
SA = 2πRh + πr²Formula-first calculators
Every result includes the exact formula, substituted values, and a readable step-by-step calculation.
Unit-aware results
Switch between metric and imperial units without leaving the page, including square-unit conversion guidance.
Built for learning
Labelled diagrams, examples, references, and related calculators help users understand the geometry.
Surface area basics
Calculate surface area with confidence
Surface area measures the total exposed area on the outside of a three-dimensional shape. Students use it to check geometry homework, teachers use it to explain nets and formulas, and builders use it to estimate paint, wrapping, insulation, coating, or material coverage. A sphere uses a radius-only formula, a cylinder combines two circular bases with one curved side, and prisms add the areas of matching faces. More specialized shapes, such as ellipsoids, torus forms, capsules, and conical frustums, need formulas that are easy to misread when copied from a textbook. This site keeps the calculator, diagram, formula, and worked steps together so the result is fast but still auditable.
Choose a calculator above, enter positive dimensions, and compare the result with the formula breakdown. For adjacent topics, use the related-shape links on each calculator page or read the articles on derivations, paint coverage, and unit conversion.
FAQ
Surface area questions
What is surface area?
Surface area is the total outside area of a three-dimensional object. It is measured in square units such as m², cm², ft², or in².
How do these calculators work?
Each calculator applies a published geometry formula, substitutes your dimensions, and shows the intermediate steps so the result can be checked by hand.
Can I use different units?
Yes. Choose meters, centimeters, millimeters, feet, inches, or kilometers. Results are shown in the matching square unit.
Are calculations stored?
No. Calculations run in your browser and are not saved as personal history.
Which calculator should I choose?
Choose the page that matches the shape. If the object is a combination of shapes, calculate each part and add the areas that are exposed.
Learn more
記事
球の表面積が 4πr² ã«ãªã‚‹ç†ç”±
Calculate and visualize surface area for common 3-D shapes with clear formulas, examples, and citations.
展開図から見る円すいと円すい台の面積
Calculate and visualize surface area for common 3-D shapes with clear formulas, examples, and citations.
表面積から塗料量を見積もる
Calculate and visualize surface area for common 3-D shapes with clear formulas, examples, and citations.