01
The purpose
What does this calculator estimate?
Material to order for the shell including rebound waste — adjusted cubic yards and batch trucks.
Construction & Design · F4
Gunite & Shotcrete Volume Calculator
Material to order for the shell including rebound waste — adjusted cubic yards and batch trucks.
Measure the inputsGunite rebounds off the rebar and shell as it's shot — order ~20% extra.
Read the full resultRebound waste is higher on vertical walls than on the floor.
Check the boundaryAn experienced nozzleman lowers rebound and gives a denser shell.
Useful forConstruction & DesignPlanningComparisonVerification
Live calculation
Gunite inputs
✓ Checked May 2026
Enter shell volume and rebound waste.
Calculated result
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Enter the required values to calculate.
Enter the known values. Let the engine handle the calculation.
✓ Formula checked↻ Live result○ No account needed
Planning estimate only. Confirm product labels, equipment specifications, qualified-professional advice and local requirements before acting.
The result, explained
Use the Gunite & Shotcrete Volume Calculator result with context.
Material to order for the shell including rebound waste — adjusted cubic yards and batch trucks.
02
The tool
What information does it use?
- Pool length: enter a measured or verified value
- Pool width: enter a measured or verified value
- Shallow end depth: enter a measured or verified value
- Deep end depth: enter a measured or verified value
- Shell thickness: Typically 6–8 inches.
- Rebound waste: Gunite rebounds ~20% during shooting.
03
The method
How to use this calculator
- Pool lengthEnter the value you can verify.
- Pool widthEnter the value you can verify.
- Shallow end depthEnter the value you can verify.
- Deep end depthEnter the value you can verify.
- Shell thicknessTypically 6–8 inches.
- Rebound wasteGunite rebounds ~20% during shooting.
04
The relationship
The formula in plain English
Ordered yards = shell concrete volume × rebound waste factor
Shell volume = surface area × thickness. Gunite rebound is ~20% (factor 1.20).05
Worked through
A worked example: 32 × 16 ft pool, 6-inch shell, 20% rebound
- Shell concrete volume = 19.7 CY
- Rebound factor = 1.20
- Order = 19.7 × 1.20 = 23.6 → 24 CY
| Pool size | Shell volume | +20% rebound | Order |
|---|---|---|---|
| 28 × 14 ft | 15.8 CY | 19.0 CY | 19 CY |
| 32 × 16 ft | 19.7 CY | 23.6 CY | 24 CY |
| 36 × 18 ft | 24.0 CY | 28.8 CY | 29 CY |
| 40 × 20 ft | 28.7 CY | 34.4 CY | 35 CY |
06
Why it matters
How the result supports the next decision
Gunite rebounds off the rebar and shell as it's shot — order ~20% extra.
Rebound waste is higher on vertical walls than on the floor.
07
Good inputs
Improve the estimate before relying on it
- Gunite rebounds off the rebar and shell as it's shot — order ~20% extra.
- Rebound waste is higher on vertical walls than on the floor.
- An experienced nozzleman lowers rebound and gives a denser shell.
- Order enough for one continuous shoot — cold joints weaken the shell.
- Confirm batch-truck access and timing so trucks arrive in sequence.
08
The boundary
How to interpret the result
Confirm structural assumptions, site conditions and local requirements with qualified professionals.
The engine reports invalid inputs and safety warnings beside the result. Resolve those messages before using the estimate.
09
Before acting
What should override this estimate?
- Measured site conditions and current test results
- Product labels and manufacturer specifications
- Qualified-professional advice and applicable local codes
10
Common questions
Frequently asked questions
How much gunite do I need to order?
Start with the shell's concrete volume — surface area times thickness — then add a rebound-waste factor of about 20 percent, since a meaningful share of gunite bounces off the rebar and surface as it's sprayed. The adjusted figure is what you actually order so the crew doesn't run short mid-shoot.
What is gunite rebound?
Rebound is the material that ricochets off the rebar grid and shell surface during spraying and falls to the floor as waste. It typically runs around 20 percent of the material shot, and is higher on vertical walls than on the floor. Ordering extra to cover rebound prevents running out before the shell is complete.
How is gunite different from shotcrete to order?
The shell volume math is identical, but gunite (dry mix hydrated at the nozzle) generally produces more rebound than wet shotcrete, so its waste factor can run a bit higher. Both should still be ordered with a waste allowance and shot continuously for a monolithic shell.
Why must gunite be shot in one continuous pour?
Stopping and restarting creates cold joints — weak seams where fresh material doesn't fully bond to set material — which become crack and leak points. Ordering enough material, including rebound waste, and sequencing the batch trucks ensures the crew can shoot the whole shell without interruption.
Does the nozzleman affect how much gunite I need?
Yes. A skilled nozzleman controls angle, distance, and pressure to minimize rebound and place dense, well-consolidated material, which reduces waste and improves shell quality. Less experienced application produces more rebound, so the waste factor — and the amount you order — effectively rises.
How much extra gunite for rebound?
About 20% above the shell concrete volume to cover material that bounces off during shooting.
Is gunite shot in one pour?
Yes — continuously, to avoid cold joints that create weak, leak-prone seams.
How much gunite for a pool?
Shell volume (surface area × thickness) times a ~1.20 rebound factor; often 18–24 CY ordered.
Primary sources
Use the result with current guidance.
These official references support safe planning context. Product labels, local requirements and qualified-professional advice take priority over a general calculator estimate.