Wall
Calculate wall area from width and height, then subtract windows and other openings row by row.
Paint Surface Area Calculator (Walls, Roofs, Tanks, Pipes, Steel Sections, Fences)
Use one tool to work out wall, roof, tank, pipe, steel section, fence, and direct-input areas. Pass the net area straight to the paint quantity calculator.
Roof pitch and cylindrical surfaces in one place
Window deductions, end caps, and factors supported
Built for international teams and projects
All inputs are processed only in this browser and are not sent to any server.
How to use
- Choose a unit system and add one row for each surface type you need.
- For walls, add openings for window and door deductions. For roofs, choose a pitch method.
- For tanks, pipes, steel sections, and fences, enter the dimensions, quantity, and factor or profile you need.
- Review the net area, then pass it to the paint quantity calculator for coating volume.
Supported shapes
Roof
Convert angle, rise/run, or percent pitch into a slope factor and apply it to the plan area.
Tank
Switch between vertical and horizontal tanks and include end caps when the spec requires it.
Pipe
Calculate the outside surface from outside diameter and length, with optional end faces.
Steel sections
Use a preset section type or enter a custom perimeter for fast coating takeoff.
Fence
Approximate single-sided, double-sided, or open-mesh fencing with an editable factor.
Direct input
Enter an area directly when the drawing or takeoff already gives you the value.
Sample
Input
Wall with window deduction
Wall 6.0 m × 3.0 m, window 1.0 m × 1.5 m × 1
Output
Gross 18.00 m² / Deduction 1.50 m² / Net 16.50 m²
Input
Roof pitch area
Roof 5.0 m × 4.0 m, pitch 45°, quantity 1
Output
Multiply the plan area by the pitch factor to get 28.28 m² net area
Formulas
- Wall: Gross area = width × height × quantity
- Opening deduction: Deduction area = Σ(opening width × opening height × quantity)
- Roof: Net area = plan area × slope factor × quantity
- Tank / pipe: Area = π × diameter × length × quantity
- Steel section: Area = perimeter × length × quantity
- Fence: Area = length × height × factor × quantity
Glossary
Gross area
The area before deductions are removed. For walls, it starts with width × height; for roofs, it starts with plan area × slope factor.
Deduction area
The area removed for windows, openings, cutouts, or similar voids.
Net area
The area that will actually be painted. This is the value you pass to the paint quantity calculator.
Slope factor
The multiplier that converts plan area into sloped roof area.
Factor
A multiplier used to approximate open fencing, double-sided coating, and similar cases.
Notice
- This result is an estimate. Always prioritize on-site measurements and the drawing set.
- Preset steel perimeters are approximate. Enter a custom perimeter if you need precision.
- Tank end caps, pipe end faces, and fence factors can vary by specification.
- After you calculate the net area, continue with the paint quantity calculator for coating volume and dilution.
FAQ
Which roof pitch input should I use?
Use the method that matches the drawing or site note: angle, rise/run, or percent. All three are converted to the same slope factor.
How accurate are the steel section areas?
The presets are quick estimating values. If you need higher accuracy, enter a custom perimeter instead.
Can I enter multiple window deductions on one wall?
Yes. Add multiple opening rows and enter each width, height, and quantity separately.
Can a shared URL restore the same state?
Yes. The shared URL can restore the row structure, unit system, and settings.
How do I hand off to the paint quantity calculator?
Use the handoff button and the net area will be carried over to the paint quantity calculator.