Formula Used
| Calculation | Formula |
|---|---|
| Rectangle area | Length × Width |
| Circle area | π × Radius² |
| Triangle area | Base × Height ÷ 2 |
| Trapezoid area | (Side A + Side B) × Height ÷ 2 |
| Sloped length factor | √(Span² + Rise²) ÷ Span, or 1 ÷ cos(Angle) |
| Allowance area | Perimeter × Linear allowance, plus corner allowance |
| Adjusted cloth area | (Sloped area + allowance area) × percentage allowance factor |
| Roll length | Total cloth area ÷ roll width |
| Fasteners | Perimeter and support length ÷ spacing, plus extra hardware |
| Total project cost | Material + labour + delivery + hardware + fixed costs + tax |
How to Use the Calculator
Enter each area and choose its matching shape. Add measurements using one consistent unit for every section. The calculator converts all measurements before completing each estimate.
Select the installation method and provide slope details when required. Add practical allowances for hems, attachments, waste, sag, and tension. These settings create a safer purchasing estimate for installation.
Enter roll dimensions, fastener spacing, material weight, and current prices. Submit the form to produce quantities, panels, hardware, and costs. Review structural requirements before ordering or installing any material.
Worked Example
A patio measures six metres by four metres. The cloth uses a 3.66-metre roll with standard allowances. The estimate includes seams, waste, fasteners, labour, and tax.
| Input | Example value |
|---|---|
| Area | 6 m × 4 m |
| Shade level | 70% |
| Roll size | 3.66 m × 50 m |
| Fastener spacing | 0.30 m |
| Waste allowance | 7% |
| Material price | £8.50 per m² |
Shade Percentage Guidance
| Shade | Common uses | General effect |
|---|---|---|
| 30%–40% | Seedlings and sun-tolerant vegetables | Light heat reduction |
| 50%–60% | Garden beds, nurseries, and patios | Balanced shade and airflow |
| 70%–80% | Leafy crops, livestock, and playgrounds | Strong heat protection |
| 90% | Privacy screens and specialised covering | Very limited direct sunlight |
Material Comparison
| Material | Strength | Typical use | Consideration |
|---|---|---|---|
| Knitted polyethylene | Flexible and tear resistant | Gardens and patios | Edges may not unravel easily |
| Woven polyethylene | Firm and economical | Large agricultural areas | Cut edges may need finishing |
| PVC-coated mesh | Durable and stable | Commercial screens | Usually heavier |
| Aluminised cloth | Reflective heat control | Greenhouses and nurseries | Often costs more |
| Natural fibre | Decorative appearance | Seasonal outdoor spaces | Weather life may be shorter |
Frequently Asked Questions
How much extra shade cloth should I buy?
Allow extra cloth for hems, fastening, overlaps, tension, and cutting. Windy sites may require larger reinforced edge allowances. A measured waste percentage helps prevent material shortages onsite.
Does shade percentage change the required area?
Shade percentage usually changes light transmission, not physical coverage. Material construction can still affect stretch and usable width. Always check the supplier specification before final purchasing decisions.
How is a sloped installation calculated?
The calculator increases the horizontal area using slope geometry. You can enter an angle or provide rise and span. The angle takes priority when both methods contain values.
Can I calculate several separate areas?
Yes, add multiple sections with different supported shapes. Each section can also represent several identical covered areas. The final result combines quantities, panels, seams, and costs.
Why can panel count exceed the area count?
Large coverings may exceed the available roll or panel width. The calculator divides each covering into practical parallel panels. Seam and panel overlaps increase the required material quantity.
How are fasteners estimated?
Fasteners are spaced around the calculated perimeter and support lines. An extra hardware percentage covers losses and difficult corners. Structural hardware still requires advice from a qualified installer.
Should cloth be stretched completely tight?
Most installations need controlled tension rather than excessive stretching. The correct method depends on cloth type and support design. Follow manufacturer guidance for tension, clips, and reinforced edges.
Can this estimate include complete rolls only?
Yes, enter the available roll length and roll price. The calculator rounds purchasing upward to complete rolls. Unused material remains available for repairs or future sections.
Does colour affect shade performance?
Colour can influence heat absorption, appearance, and transmitted light quality. Published shade percentage remains the main comparison figure. Supplier data provides the best performance details for colours.
Can I use imperial measurements?
Yes, select inches, feet, or yards before entering dimensions. The calculator converts values internally for consistent results. Outputs return using the selected measurement unit where practical.
Is this calculator a structural design tool?
No, this tool estimates material, layout, hardware, and project costs. Wind, snow, anchoring, and support loads need engineering review. Consult qualified professionals before building exposed or elevated structures.
Practical Disclaimer
This calculator provides planning estimates from the values entered. Actual products, cutting methods, seams, and site conditions can vary. Confirm final quantities with suppliers and qualified installers before purchase.