Know How Much Gravel You Need Before You Order

How to use the Gravel Project Planner

1. Measure. Enter the length and width of a rectangular area in feet and your intended finished layer depth in inches. Choose the depth for your project; this calculator does not recommend one.
2. Plan Order. Leave extra allowance at 0% unless you choose to add material. Decide separately whether a loose-to-finished adjustment applies.
3. Add Supplier Details. Enter the selling increment for bulk material. To estimate cost, add the supplier’s price per cubic yard and confirm delivery and any additional fees.
4. Review Project Sheet. Check the quantities, assumptions and open questions together before contacting the supplier. You can print the sheet even when some information is still missing.

Return to Measure whenever you are ready to enter your project.

How much gravel do I need?

For a rectangular layer with uniform depth, multiply length by width by depth. Keep the units consistent: divide inches by 12 to get feet, then divide cubic feet by 27 to get cubic yards. Combined, those two conversions give:

Cubic yards = Length (ft) × Width (ft) × Depth (in) ÷ 324

A cubic yard is a unit of volume, not weight. The formula describes the measured space; it does not add extra material or round an order to a supplier’s selling increment.

Measured Volume vs. Planning Volume vs. Purchase Quantity

Measured Volume

The geometric volume calculated directly from your measurements. It remains the same when you change allowance, supplier details or costs.

Planning Volume

Measured volume after your explicit planning decisions: extra allowance first, then any enabled and valid loose-to-finished adjustment. With neither adjustment, it equals measured volume.

Purchase Quantity

Planning Volume rounded up to the increments your supplier sells. It remains unanswered until you enter the Supplier Selling Increment; using Measured Volume directly would skip an ordering decision.

Extra allowance is not the same as loose-to-finished adjustment

Allowance is material you deliberately choose to add beyond the measured requirement. Loose-to-finished addresses a different question: how much loose material corresponds to the finished layer you want. Confirm any factor for the specific material and condition with your supplier or the product documentation. Neither decision has a universal recommended percentage here.

The planner applies allowance before the loose-to-finished factor and keeps their origins visible. An exact calculation does not turn a planning assumption into supplier confirmation.

Why we don’t automatically convert gravel to tons

Weight requires density for the material in the relevant condition. Material type, particle-size distribution (gradation), moisture and how the material is placed can affect that relationship. FHWA’s discussion of material properties and moisture-density relationships explains why condition matters.

This version plans bulk purchases by volume. It does not calculate tons or bag counts, and it needs no density for that route. A future weight route will require valid, compatible density information instead of a silent generic conversion.

What to ask your gravel supplier before ordering

Use the short question card above as a conversation starter. Record the answers for the material you intend to buy, rather than borrowing terms from another supplier.

What increments do you sell bulk gravel in?

Enter that quantity in Supplier Selling Increment. A measured quantity is not necessarily a quantity the supplier sells.

What is your price per cubic yard?

Enter the actual USD price for this material. A price of zero requires explicit confirmation; an empty price means unknown.

Does delivery apply? Are there additional fees?

Resolve each charge separately. Free delivery confirmed at $0 differs from customer pickup, where delivery does not apply.

Is there a material-specific loose-to-finished factor I should use?

Confirm the factor’s basis and whether it applies to your intended finished condition before enabling it.

Are there minimum order requirements?

Check this directly before placing an order. Minimum orders are not applied by this version of the planner.

Known costs, with clear boundaries

Material Subtotal uses Purchase Quantity and the supplier unit price you entered. Pre-tax Total adds resolved delivery and fees. Taxes are not included. Unknown charges remain questions, not automatic zeros, and a calculated total is not a supplier quote.

What your Project Sheet means

The sheet brings together your measurements, calculated quantities, planning choices, supplier information, confirmed costs and open questions. “Planning sheet — information to confirm” means that purchase information is still incomplete. “Purchase Quantity calculated from the information provided” means the quantity is ready based on your entries; costs may still need confirmation.

Before You Order identifies missing or invalid dependencies and links back to where you can resolve them. Review it with the supplier: the sheet is not an order confirmation, a supplier quote or an availability guarantee.

Review or print your Project Sheet.

How this planner calculates your project

The calculation engine carries full internal precision through each step. Rounding shown on screen is for reading; later calculations use the internal value. Purchase rounding is a separate operation that rounds upward only after a valid selling increment is supplied.

Only the planning choices you make are applied. CALCULATED identifies a direct calculation; SUPPLIER-BASED identifies a dependency on supplier information; PLANNING ESTIMATE retains an explicit planning assumption. NEEDS INPUT names missing information, while CHECK INPUT asks you to correct a supplied value. Changing an input clears obsolete dependent results while preserving independent valid ones.

What this planner does not assume

There is no hidden waste percentage, universal gravel density, automatic loose-to-finished factor, default supplier increment or default gravel price. Delivery and fees are not filled in automatically. The current interface supports one rectangular area and bulk ordering by volume; other shapes, multiple areas, tons and bags are outside this version.

Sources and conversion basis

Unit conversions follow the international foot and inch. NIST’s Guide to the SI, Appendix B.9 provides the length and volume conversion basis. The worked example above is checked against the same engine used by the planner.

Physical material properties are discussed in the linked FHWA reference. Those references do not certify a supplier’s material, selling terms or prices; obtain those details from your supplier.