How to do an earthwork takeoff from a grading plan

Earthwork is the scope most likely to make or break a site bid, and the one least forgiving of a sloppy takeoff. The quantities are large, the unit costs are volatile, and an error compounds: get the cut wrong and you also get the haul, the import, the equipment hours and the schedule wrong.

Read the grading plan before you measure it

Start by separating what the sheet is telling you. Existing contours (usually dashed or screened) describe the surface you have. Proposed contours (solid, heavier) describe the surface you are being paid to create. Spot elevations, finish floor elevations, and rim/invert callouts pin down points the contours only approximate.

• Confirm the contour interval — 1', 2' and 5' intervals change your interpolation entirely.
• Note the datum and whether existing grades came from survey or from an older as-built.
• Find the limits of disturbance; earthwork stops there even if contours continue.
• Flag areas with no proposed contours — they usually mean match existing.

Pick a method: grid or average end area

The grid method overlays a regular grid on the site, reads existing and proposed elevation at each node, and multiplies the average depth difference by the cell area. It suits open sites, pads and parking fields. Average end area suits linear work — roadways, channels, trench corridors — where you have cross sections at stations.

For a bid-level takeoff, a 25' grid on a typical commercial site is usually enough; tighten to 10' where the surface changes fast. The purpose is a defensible number, not a construction-grade model.

Keep mass grading separate from the sections

The single most common earthwork mistake is folding everything into one cut-fill number. These belong on separate lines because they are performed by different crews, at different times, at different unit costs:

1. Clearing and grubbing — area, in SF or acres.
2. Topsoil strip — area times strip depth, stockpiled or hauled.
3. Mass cut and fill — the surface-to-surface volume.
4. Subgrade/undercut below paved sections — area times the section thickness.
5. Structural fill and stone sections — separate materials, separate lines.
6. Topsoil respread and restoration — area times respread depth.

Undercut for a pavement section is not mass grading. If the grading plan finishes at subgrade, the stone and asphalt thickness has already been accounted for. If it finishes at top of pavement, you owe an additional cut equal to the section thickness across the paved area.

Convert honestly: bank, loose and compacted

A cubic yard is not one thing. Measured in place it is bank CY. In a truck it is loose CY. Placed and compacted in a fill it is compacted CY. Swell and shrinkage factors are soil-dependent and should come from the geotech report when one exists.

State the assumption on the line item. A cut of 4,200 CY means very little on its own; "4,200 bank CY, 15% swell assumed for haul" can be checked and challenged.

Balance the site, then decide the story

Once cut and fill are computed, compare them in compacted terms. A site that balances on paper rarely balances in the field, because unsuitable material, moisture conditioning and the section undercut all consume fill. Decide explicitly whether you are exporting, importing, or holding material on site, and price the haul accordingly — that decision, not the raw volume, is usually where bids diverge.

Checks before you price

• Does your disturbed area match the erosion control plan's disturbed acreage?
• Does the average depth over the site look plausible for the contour change shown?
• Have you double-counted anywhere two sheets overlap at a match line?
• Did you include pond, trench and structure excavation, or are those separate scopes?
• Is the strip area consistent with the clearing area you took off?

Earthwork rewards a takeoff that is transparent about its assumptions. Keep the measurement, the method and the conversion factors visible, and a reviewer can find a disagreement in minutes instead of rebuilding your work from scratch.