Rectangular prism
8 x 5 x 3158 square units
Surface Area Calculator
Use this free surface area calculator to find outside area for rectangular prisms, cubes, cylinders, spheres, and cones with formula steps.
Unit-aware inputs Formula note Example numbers Tab-only history
SA = 2lw + 2lh + 2wh158 cm^2
- Length
- 8 cm
- Width
- 5 cm
- Height
- 3 cm
Steps
- Choose rectangular prism mode.
- Use SA = 2lw + 2lh + 2wh.
- Substitute the entered measurements.
- The surface area is 158 cm^2.
How to use the Surface Area Calculator
- Choose the solid shape: rectangular prism, cube, cylinder, sphere, or cone.
- Enter the required measurements for that shape.
- Press Calculate surface area to see the square-unit result and formula steps.
- Use examples, recent answers, or copy the result while checking geometry work.
What people use it for
Find the outside area of common 3D solids.
Compare surface area for boxes, cylinders, spheres, and cones.
Check square-unit answers for geometry homework.
Copy formulas and results into notes while comparing shapes.
Quick examples
Sphere
r=4201.06192983 square units
Cylinder
r=3, h=10245.04422698 square units
Need the guide or a nearby tool?
Need a slower walkthrough, a related calculator, or the full library? These links keep you close to the task you started.
- How to use the Surface Area Calculator See slower examples, input meanings, formula notes, result limits, and mistakes to avoid.
- Calculators Browse related calculators and utilities in the same category.
- Calculator and utility guides Find more guides that use real tool inputs and example numbers.
- All free tools Search every live tool, converter, calculator, AI helper, and browser utility.
Frequently asked questions
Quick answers about formulas, units, valid measurements, examples, copying, and private in-browser history.
Which shapes are supported?
The Surface Area Calculator supports rectangular prism, cube, cylinder, sphere, and cone modes.
What units should I use?
Use the same length unit for every measurement. The result is reported in square units, such as cm^2 or ft^2.
What do the main Surface Area Calculator inputs mean?
The main inputs are the numbers, operation, mode, or known values the calculator needs. Keep units consistent, enter percentages the way the page label shows, and use the examples as a quick check before trusting the answer.
How should I read the Surface Area Calculator answer?
Read the headline answer, then check the supporting lines and examples to understand how the calculator got there. If one input changes, rerun the tool and compare the new answer instead of guessing.
What should I double-check before trusting the Surface Area Calculator?
Check units, signs, rounding, and the selected mode before copying the answer. If the number feels weird, rerun one of the examples first, then put your own values back in slowly.
How does cone surface area work?
Cone surface area uses pi r(r + l). This calculator finds slant height l from radius and vertical height using the Pythagorean theorem.
What is the difference between surface area and volume?
Surface area measures the outside of a solid in square units. Volume measures the space inside a solid in cubic units.
Can this calculate flat 2D shapes?
Use the Area Calculator for flat shapes such as rectangles, triangles, circles, trapezoids, and parallelograms.
Is my surface area history private?
Yes. Recent surface area answers stay only in the current browser tab while you use the page. They are not sent to a server.
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