How deep should a horse arena base be?

Penn State Extension gives 4 to 6 inches of compacted crushed aggregate as the usual figure for firm, well-drained ground. NRCS TN 210-AEN-4 gives a wider range of 6 to 25 inches depending on subgrade strength, so soft, wet or clay sites need considerably more.

How much aggregate do I need for an arena base?

Multiply arena length by width, multiply by the compacted base depth in feet, then divide by 27 for compacted cubic yards. Aggregate is delivered loose and compacts as it is rolled, so add roughly 20 percent to get the loose volume to order. This calculator estimates tons using 1.4 tons per cubic yard of compacted dense-graded aggregate.

Why order more aggregate than the finished base volume?

Because loose aggregate takes up more space than compacted aggregate. A base specified at 6 inches compacted needs roughly 20 percent more loose material spread and rolled to finish at that depth. Ordering the compacted figure is the most common way people come up short.

What slope should an arena base have?

Extension guidance is 1 to 2 percent slope across the finished base so water drains rather than standing under the footing. The slope is built into the base, not the footing layer above it.

Horse property planning / Arena base

Horse Arena Base Calculator: Aggregate Tons by Arena Size

The layer under the footing decides whether the arena drains or ruts. Work out the compacted depth, the loose volume to order, and the tonnage before you call the quarry.

Step 01

Set the arena

Live estimate

Arena preset

Subgrade

Firm, well-drainedSand or gravel soils that stay solid wet. AverageHolds up most of the year, soft after heavy rain. Soft, wet or clayRutting, standing water, or heavy clay.

Base depth (compacted) 6 in

Average subgrade usually wants 6 to 10 inches compacted.

Waste factor (optional) %

Room for spillage, uneven subgrade, and edges. 0–15%.

Step 02

Calculated live

Your base estimate

Tons needed — tons of aggregate

Area: — sq ft
Volume: — cubic feet
Compacted: — cubic yards (finished, in place)
With 5% waste: — cubic yards loose | — tons

Based on 1.40 tons per cubic yard of compacted dense-graded aggregate.

Then comes the footing.

The base is the load-bearing layer. The footing is the cushion that sits on top of it, and the two are ordered separately.

Next step: work out the sand or blended footing with the horse arena footing calculator.

Common questions

What people get wrong about the base.

How deep should a horse arena base be?: Penn State Extension gives 4 to 6 inches of compacted crushed aggregate as the usual figure for firm, well-drained ground. NRCS TN 210-AEN-4 gives a wider range of 6 to 25 inches depending on subgrade strength, so soft, wet or clay sites need considerably more.
How much aggregate do I need for an arena base?: Multiply arena length by width, multiply by the compacted base depth in feet, then divide by 27 for compacted cubic yards. Aggregate is delivered loose and compacts as it is rolled, so add roughly 20 percent to get the loose volume to order. This calculator estimates tons using 1.4 tons per cubic yard of compacted dense-graded aggregate.
Why order more aggregate than the finished base volume?: Because loose aggregate takes up more space than compacted aggregate. A base specified at 6 inches compacted needs roughly 20 percent more loose material spread and rolled to finish at that depth. Ordering the compacted figure is the most common way people come up short.
What slope should an arena base have?: Extension guidance is 1 to 2 percent slope across the finished base so water drains rather than standing under the footing. The slope is built into the base, not the footing layer above it.

Read the guidance

Sources worth keeping nearby.

NRCS AEN-4 Earth and Aggregate Surfacing Design Guide
Penn State Extension Riding Arena Footing Material Selection and Management
Rutgers E296 Horse Facilities