Formula used
Layer area = wall coverage length × reinforcement depth Net geogrid area = sum of every layer area Overlap area = panel joint count × overlap width × reinforcement depth Connection allowance area = wall coverage length × connection allowance Waste area = adjusted layer area × waste percentage Gross purchase area = net area + overlap + connection allowances + waste Area-based rolls = ceiling(purchase area ÷ roll area) Recommended rolls = higher of area-based rolls, cutting-layout rolls, and minimum order Total cost = discounted materials + labor + equipment + accessories + delivery + handling + cutting + tax + contingency
How to use this calculator
- Select the calculation mode, units, and currency.
- Enter wall geometry from the approved project drawings.
- Generate the layer schedule, then edit each row.
- Add geogrid products with verified roll and pricing data.
- Select relevant site conditions and surcharge warnings.
- Enter labor, delivery, tax, and contingency costs.
- Calculate, review warnings, and export the report.
Example data
| Input | Example | Purpose |
|---|---|---|
| Wall length | 80 ft | Defines layer coverage. |
| Exposed wall height | 8 ft | Supports schedule generation. |
| Vertical spacing | 2 ft | Creates four typical layers. |
| Grid length | 6 ft | Sets reinforcement depth. |
| Roll size | 6 ft × 150 ft | Controls roll optimization. |
| Waste | 8% | Allows for trimming and damage. |
| Labor rate | $55 per hour | Estimates installation labor. |
Important design notice
This tool estimates geogrid quantities and project costs. It does not perform complete retaining wall stability design. Use approved plans and qualified engineering review.
External, internal, connection, settlement, bearing, sliding, overturning, pullout, rupture, compound, global, drainage, and seismic checks may be required. Product strength must match the final design. Never select a weaker product using price alone.
Frequently asked questions
Does this calculator design the wall?
No. It estimates quantities and costs from entered assumptions. Final reinforcement design needs professional review.
Why does the layer schedule matter?
Each layer may have different coverage and depth. The schedule produces a more accurate estimate.
How is overlap calculated?
The calculator estimates panel joints across each layer. It applies the larger selected overlap allowance.
Why can layout rolls exceed area rolls?
Roll dimensions can create unusable cutting patterns. The cutting plan captures this practical limitation.
Can I use several geogrid strengths?
Yes. Assign a product to every layer. The report groups quantities and costs by product.
What counts as a reusable offcut?
An offcut is reusable when its remaining length meets your minimum setting. Site rules may differ.
How are labor hours estimated?
Gross purchase area is divided by installation productivity. The result is multiplied by the labor rate.
Should surcharges change the grid layout?
They often can. This calculator issues warnings only. Use the approved engineering schedule.
Can I use metric units?
Yes. Select metric before entering values. Keep all dimensions consistent within one calculation.
What should I include in costs?
Include materials, labor, delivery, equipment, accessories, tax, and contingency. Add project-specific charges where required.