How is annulus volume calculated?

Subtract casing outside diameter area from borehole area and multiply by grouted length: V = π/4 × (D_bh^2 − D_casing^2) × L.

What overage percentage should I use?

Use 10–30% depending on losses and site practices. Adjust to specifications and experience.

How are bags estimated?

Gross volume is converted to mass using slurry density, then divided by bag mass to get bags required.

Can I work in inches and feet?

Yes. Switch to Imperial mode to input inches and feet. Calculations are performed in SI internally.

Does this include formation porosity?

No. The tool computes borehole/annulus volume only. Handle formation voids via the overage factor or project-specific modeling.

How accurate are the default densities?

They are generic planning values. Replace with supplier mix data for production and compliance.

Borehole Grout Volume Calculator

Input Parameters

Unit system

Metric

Imperial

mm / m

Overage / wastage (%)

Covers losses, voids, and returns.

Borehole diameter

Casing OD (optional)

Set to 0 if no casing or unknown.

Grout from depth

Grout to depth

Mix density

kg/m³

Grout slurry density. Editable preset.

Bag size

Used to estimate bags required.

Results

Net Volume (m³)

0.000

Gross Volume with Overage (m³)

0.000

Liters

Cubic Feet

US Gallons

Bags Required

Parameter	Value

Formula Used

Annular cross‑sectional area:

A = \u03C0/4 \u00D7 (D_bh² - D_casing²)

Interval length:

L = \u007Cdepth_to - depth_from\u007C

Net volume:

V_net = A \u00D7 L

Gross volume with overage:

V_gross = V_net \u00D7 (1 + overage/100)

Total mass and bags:

m = V_gross \u00D7 \u03C1, bags = m / bag\_mass

All calculations run internally in SI units; imperial inputs are converted.

How to Use

Choose Metric or Imperial.
Enter borehole diameter and optional casing outside diameter.
Set the grouting interval using from/to depths.
Adjust overage to cover losses and returns.
Review mix density and bag size to estimate bags.
Click Calculate; export results to CSV or PDF.

Example Data Table

Unit System	Borehole Ø	Casing OD	From Depth	To Depth	Overage %	Mix Density	Bag Size	Volume (m³)	US Gallons	Bags
Metric	150 mm	0 mm	0 m	20 m	15%	1900 kg/m³	50 kg	–	–	–
Imperial	8.5 in	5.5 in	0 ft	120 ft	20%	118.6 lb/ft³	94 lb	–	–	–
Metric	200 mm	114 mm	5 m	35 m	10%	1850 kg/m³	25 kg	–	–	–

FAQs

We subtract casing outside diameter area from the borehole area using V = \u03C0/4 \u00D7 (D_bh² - D_casing²) \u00D7 L, where L is the grouted length.

Typical values range 10–30% depending on formation losses, tremie efficiency, and site practices. Adjust to local specs or prior project experience.

We convert gross volume to required mass using slurry density, then divide by bag mass. Change density or bag size to match the selected grout mix.

Yes. Switch to Imperial to input inches for diameters and feet for depths. Internally, the calculator converts to SI for consistent results.

No. This tool computes borehole/annulus volume. Formation voids and fractures are indirectly handled by the overage factor; adjust based on geotechnical guidance.

Defaults are generic for planning. Always replace with mix‑design or supplier data sheets for production calculations and compliance submittals.

Reference: Mix Yield Examples

Computed from bag mass and slurry density. Actual yields depend on mix design and water content.

Case	Bag mass	Density	Yield (L/bag)	Yield (ft³/bag)	Yield (US gal/bag)

Reference: Annulus Volume per Depth

Values exclude overage and assume concentric circular geometry.

Metric — liters per meter

Borehole Ø (mm)	Casing OD (mm)	Volume (L/m)

Imperial — US gallons per foot

Borehole Ø (in)	Casing OD (in)	Volume (gal/ft)