What is the Pergola Calculator?

The Pergola Calculator is a free online tool that helps you perform construction calculations quickly and accurately. Simply enter your values and get instant results.

How do I use the Pergola Calculator?

Enter the required values in the input fields, select your preferred units if applicable, and the calculator will automatically compute the results. The interface is designed to be intuitive and easy to use.

Is the Pergola Calculator free to use?

Yes, the Pergola Calculator is completely free to use. There are no hidden fees, subscriptions, or limitations on the number of calculations you can perform.

Can I use the Pergola Calculator on mobile devices?

Yes, the Pergola Calculator is fully responsive and works seamlessly on all devices including smartphones, tablets, and desktop computers.

How accurate is the Pergola Calculator?

The Pergola Calculator uses precise mathematical formulas and algorithms to ensure accurate results. However, always verify critical calculations with professional standards or consultants when needed.

Pergola Calculator

Calculate posts, beams, rafters, purlins, and materials for your pergola project. Get accurate lumber quantities and cost estimates.

Calculate Pergola Materials

Length (feet)

Beam direction

Width (feet)

Rafter direction

Height (feet)

Wood Type

Lifespan: 15-20 years

Post Size

Beam Size

Rafter Size

Rafter Spacing (inches)

Post Depth (inches)

Include Purlins (Cross Slats)

Purlin Size

Purlin Spacing (inches)

Material Pricing ($)

Post (each)

Beam (each)

Rafter (each)

Purlin (each)

Concrete (60lb)

Hardware Set

Materials Needed

Posts (12ft)

Beams (12ft)

Rafters (11ft)

Purlins (13ft)

Concrete (60lb)

418

Board Feet

120

Sq Ft Coverage

$6.92

Per Sq Ft

Hardware Needed

4 Post Brackets

4 Beam Hangers

10 Rafter Ties

16 Lag Bolts

Cost Breakdown

Posts (4)$180.00

Beams (4)$140.00

Rafters (10)$200.00

Purlins (11)$88.00

Concrete (12 bags)$72.00

Hardware & Fasteners$150.00

Total Estimated Cost$830.00

Pergola Anatomy

PostsVertical supports, typically 4 for rectangular pergola. Set in concrete footings.

BeamsHorizontal members running the length, resting on posts. Usually doubled for strength.

RaftersHorizontal members running across the width, sitting on top of beams.

PurlinsOptional cross slats running perpendicular to rafters for extra shade.

Standard Configurations

• Freestanding: 4 posts, all set in concrete
• Attached: 2 posts, ledger board on house
• Shade level: Controlled by rafter/purlin spacing
• Decorative ends: Often curved or angled for style

Wood Type Comparison

Wood Type	Cost	Lifespan	Maintenance
Pressure-Treated ★	$	15-20 years	Stain every 2-3 years
Cedar	$$	20-25 years	Optional sealer
Redwood	$$$	25-30 years	Minimal
Douglas Fir	$$	15-20 years	Stain/paint required

Lumber Sizing Guide

Component	Recommended Size	Max Span
Posts	6×6	-
Beams (doubled)	2×10 or 2×12	10-12 ft
Rafters	2×6 to 2×10	8-14 ft
Purlins	2×2 to 2×4	Rafter spacing

Formulas Used

Number of Rafters

Rafters = (Length × 12 ÷ Spacing) + 1

Number of Purlins

Purlins = (Width × 12 ÷ Spacing) + 1

Post Length

Post Length = Height + (Buried Depth ÷ 12)

Board Feet

BF = (Pieces × Length × Width × Thickness) ÷ 12

Installation Tips

1️⃣

Check Local Codes: Many areas require permits for pergolas. Check setback and height requirements.

2️⃣

Level Posts First: Use braces and a level to ensure all posts are plumb before concrete cures.

3️⃣

Double the Beams: Two 2×10s or 2×12s sandwiching the post provides better support than a single beam.

4️⃣

Add Decorative Ends: Cut rafter and purlin ends at angles or curves for visual appeal.

5️⃣

Consider Future Shade: Plan for climbing plants or shade cloth attachment points.

Frequently Asked Questions

How much shade does a pergola provide?▼

Traditional open-rafter pergolas provide about 25-50% shade. Adding purlins increases this to 50-75%. For maximum shade, add retractable fabric, climbing plants, or shade sails.

Do I need a permit for a pergola?▼

Permit requirements vary by location. Freestanding pergolas under 120 sq ft often don't need permits, but attached pergolas usually do. Always check local building codes.

How deep should pergola post holes be?▼

Post holes should be at least 24" deep for attached pergolas and 36" for freestanding. In cold climates, dig below the frost line to prevent heaving.

What size posts do I need?▼

6×6 posts are standard for most residential pergolas. Use 4×4 only for small decorative pergolas. Consider 8×8 for large spans or heavy snow loads.

Can I attach a pergola to my house?▼

Yes, using a ledger board attached to the house framing (similar to a deck ledger). This requires proper flashing and fastening to prevent water damage.

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Pergola Anatomy

PostsVertical supports, typically 4 for rectangular pergola. Set in concrete footings.

BeamsHorizontal members running the length, resting on posts. Usually doubled for strength.

RaftersHorizontal members running across the width, sitting on top of beams.

PurlinsOptional cross slats running perpendicular to rafters for extra shade.

Standard Configurations

• Freestanding: 4 posts, all set in concrete
• Attached: 2 posts, ledger board on house
• Shade level: Controlled by rafter/purlin spacing
• Decorative ends: Often curved or angled for style

Wood Type

Cost

Lifespan

Maintenance

Pressure-Treated ★

15-20 years

Stain every 2-3 years

Cedar

20-25 years

Optional sealer

Redwood

$$$

25-30 years

Minimal

Douglas Fir

15-20 years

Stain/paint required

Component

Recommended Size

Max Span

Posts

6×6

Beams (doubled)

2×10 or 2×12

10-12 ft

Rafters

2×6 to 2×10

8-14 ft

Purlins

2×2 to 2×4

Rafter spacing

Installation Tips

1️⃣

Check Local Codes: Many areas require permits for pergolas. Check setback and height requirements.

2️⃣

Level Posts First: Use braces and a level to ensure all posts are plumb before concrete cures.

3️⃣

Double the Beams: Two 2×10s or 2×12s sandwiching the post provides better support than a single beam.

4️⃣

Add Decorative Ends: Cut rafter and purlin ends at angles or curves for visual appeal.

5️⃣

Consider Future Shade: Plan for climbing plants or shade cloth attachment points.

Frequently Asked Questions

How much shade does a pergola provide?▼

Traditional open-rafter pergolas provide about 25-50% shade. Adding purlins increases this to 50-75%. For maximum shade, add retractable fabric, climbing plants, or shade sails.

Do I need a permit for a pergola?▼

Permit requirements vary by location. Freestanding pergolas under 120 sq ft often don't need permits, but attached pergolas usually do. Always check local building codes.

How deep should pergola post holes be?▼

Post holes should be at least 24" deep for attached pergolas and 36" for freestanding. In cold climates, dig below the frost line to prevent heaving.

What size posts do I need?▼

6×6 posts are standard for most residential pergolas. Use 4×4 only for small decorative pergolas. Consider 8×8 for large spans or heavy snow loads.

Can I attach a pergola to my house?▼

Yes, using a ledger board attached to the house framing (similar to a deck ledger). This requires proper flashing and fastening to prevent water damage.

Pergola Calculator

Table of Contents

Calculate Pergola Materials

Material Pricing ($)

Materials Needed

Hardware Needed

Cost Breakdown

Pergola Anatomy

Standard Configurations

Wood Type Comparison

Lumber Sizing Guide

Formulas Used

Number of Rafters

Number of Purlins

Post Length

Board Feet

Installation Tips

Frequently Asked Questions

Did you find this calculator helpful?

Loading Calculator...

Pergola Calculator

Table of Contents

Calculate Pergola Materials

Material Pricing ($)

Materials Needed

Hardware Needed

Cost Breakdown

Pergola Anatomy

Standard Configurations

Wood Type Comparison

Lumber Sizing Guide

Formulas Used

Number of Rafters

Number of Purlins

Post Length

Board Feet

Installation Tips

Frequently Asked Questions

Did you find this calculator helpful?

Pergola Calculator

Table of Contents

Calculate Pergola Materials

Material Pricing ($)

Materials Needed

Hardware Needed

Cost Breakdown

Pergola Anatomy

Standard Configurations

Wood Type Comparison

Lumber Sizing Guide

Formulas Used

Number of Rafters

Number of Purlins

Post Length

Board Feet

Installation Tips

Frequently Asked Questions

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Board Foot Calculator

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Loading Calculator...

Pergola Calculator

Table of Contents

Calculate Pergola Materials

Material Pricing ($)

Materials Needed

Hardware Needed

Cost Breakdown

Pergola Anatomy

Standard Configurations

Wood Type Comparison

Lumber Sizing Guide

Formulas Used

Number of Rafters

Number of Purlins

Post Length

Board Feet

Installation Tips

Frequently Asked Questions

Related Calculators

Deck Calculator

Lattice Calculator

Fence Calculator

Board Foot Calculator

Did you find this calculator helpful?