How much gravel do I need for a 18-foot round patio base?

For a 18-foot diameter patio (254 sq ft) with a standard 4-inch base, you'll need ~4.1 cubic yards (4" base), including 30% extra for compaction.

18-Foot Round Patio Calculator

Q: How do you calculate the area of a circular patio?

Use the formula: Area = π × (diameter/2)². For a 18-foot diameter patio: Area = 3.14159 × (18/2)² = 254 square feet.

An 18-foot diameter circular patio offers about 254 square feet - generous space for entertaining around a fire pit.

Diameter

18 feet

Area

254 sq ft

Size Category

Large

Fire Pit

44-48 inch fire pit

Materials Flagstone Cost Estimate

Calculate Materials

Circular Patio Formula: Area = π × (diameter ÷ 2)²
18' diameter = 3.14159 × 9² = 254 sq ft

Patio Area (square feet)

Pre-filled for 18-foot diameter circle. Adjust if needed.

Stone Type

Material Requirements

Note for circular patios: Round patios require more cutting, especially around the edges. Consider ordering 15-20% extra stone (rather than 10%) to account for curved cuts and fitting.

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About 18-Foot Round Patios

An 18-foot diameter circular patio offers about 254 square feet - generous space for entertaining around a fire pit.

Perfect For

Fire pit with 6-8 seats
Large curved sectional
Outdoor dining for 8
Multi-purpose gathering space

Design Tips

Accommodates a 44-48 inch fire pit with generous seating
Consider two seating areas on opposite sides
Built-in seating walls work beautifully at this size

Recommended Fire Pit Size

For a 18-foot diameter patio, we recommend a 44-48 inch fire pit. This provides 6-7 feet of clearance around the fire pit for safety and comfortable seating.

Quick Material Estimates

Stone (Flagstone)

2.5-3.2 tons flagstone

Base Gravel

~4.1 cubic yards (4" base)

* Estimates vary by stone type. Add 15-20% for circular patio cutting waste.

Design First, Order Only What You Need

Circular patios require 15-20% extra stone for curved cuts. Plan your layout digitally first to see exactly how your stones fit — and stop over-ordering.

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No card. The 7-day trial starts after your first successful stone processing.

Other Round Patio Sizes

Small

Medium

Large

18' diameter (254 sq ft)
20' diameter (314 sq ft)

Extra Large

24' diameter (452 sq ft)

Rectangular Patio Sizes

View all sizes →

Related Resources

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01 I’m choosing a material

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02 I need to know how much to order

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03 My stones are delivered

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04 I want someone to plan or install it

Have an experienced stonemason design the layout for your actual stones, or use the field guide with an installer you choose.

See the Patio Design Service Use the DIY layout guide

18-Foot Round Patio FAQ

How much stone do I need for a 18-foot round patio?

A 18-foot diameter circular patio covers 254 square feet. For flagstone, you'll need approximately 2.5-3.2 tons flagstone. Order 15-20% extra for cuts and waste, as circular patios require more trimming than rectangular ones.

How do you calculate the area of a circular patio?

Use the formula: Area = π × (diameter ÷ 2)². For a 18-foot diameter patio: Area = 3.14159 × (18 ÷ 2)² = 3.14159 × 9² = 254 square feet.

What size fire pit fits a 18-foot round patio?

For a 18-foot diameter patio, we recommend a 44-48 inch fire pit. This provides 6-7 feet of clearance around the fire pit for safety and allows room for comfortable seating. Always follow local fire codes and manufacturer recommendations.

Why do circular patios need more material?

Circular patios require more cutting to achieve the curved edges. Plan for 15-20% waste factor instead of the typical 10% for rectangular patios. The smaller the patio, the higher the percentage of edge cuts relative to the total area.