Match the sketch to the project
For a driveway, separate the main strip, wider parking area and any changing-width approach. For a shed base, measure the selected pad boundary rather than assuming it equals the shed dimensions. For a patio, measure the selected base separately from bedding and pavers. For a walkway, split bends and width changes into manageable measured sections. For custom fill, name each section and state its purpose.
The Gravel Calculator changes prompts for these contexts. It does not choose their depths. Obtain the material and layer specification for your actual project externally, then record the dimensions.
Record the layer state
Measure length and width horizontally; depth is the selected thickness perpendicular to the footprint. Where depths vary, use separate zones rather than silently applying the deepest reading everywhere. Record whether this is a loose layer or a finished compacted layer. Do not pair a finished compacted volume with a loose-delivery density and call it a delivery order without a supplier-supported conversion.
Gradation, particle shape, fines, drainage and compaction influence granular-base behavior, as explained in FHWA-RD-97-148, Granular Base. Quantity arithmetic does not approve bearing capacity or drainage design.
Worked walkway estimate
For the loadable walkway record, mark both ends of the 20 ft run, record its 3 ft width and label the illustrative 4 in depth. Note whether that depth describes loose material or a finished layer. Keep the selected 10% extra in its own field. The example density is invented: replace it with the exact supplier material, value, units and state statement before using estimated weight for a quote. Compare the entered section ID and dimensions with your sketch; the density methodology explains the conversion rather than supplying field specifications.
The calculator retains base volume and volume with extra separately. Apply that extra once: if you transfer an adjusted volume to Aggregate Ordering, do not add the same allowance again.
Ask the supplier
Keep gravel, sand and crushed-stone identities distinct when comparing quotes. USGS construction sand and gravel information provides construction-aggregate terminology and use context; it does not establish the density of your selected delivery.
Record the exact material, density value, units, moisture/state basis and source statement. Ask whether “tons” means US short tons, whether the quote uses loose cubic yards, and what minimum, increment and delivery terms apply. Enter short tons per cubic yard directly when that is the supplied conversion.
FHWA NHI-05-037, Table 5-17 describes compacted dry geotechnical reference ranges. They are not delivered-loose gravel presets. Read the density methodology and yards versus tons decision before converting. For drain-specific displacement and permanent safety boundaries, use the ordinary yard-drain guide.