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Excavation

What it's for

Figures the dirt coming out of a rectangular dig and the trucks to haul it. You get the volume in the ground, the larger volume once it is dug and loose, the number of truck loads, and the gravel for the base in yards and tons, with a section drawing of the cut. It is a quantity takeoff. It does not design the slope or shoring of the cut.

Step by step

The example is the screen as it opens: a dig 30' 0" by 20' 0" and 4' 0" deep, in loam, with 12 yd³ trucks and a 6" gravel base.

Excavation inputs at their defaults: LENGTH 30' 0", WIDTH 20' 0", DEPTH 4' 0", SOIL TYPE Loam (25%) picked among Sand (12%), Loam (25%) and Clay (40%), TRUCK CAPACITY 12 yd³ with a stepper, GRAVEL BASE DEPTH 6". The answer bar reads 10 truck loads, ≈ 88.9 yd³ bank · ≈ 111.1 yd³ loose. RESULTS reads ≈ 88.9 yd³ bank · ≈ 111.1 yd³ loose; +25% swell — Loam (25%); Laid back 1-1/2:1 (OSHA, unclassified): ≈ 140.4 yd³ bank — not in the volume above; The drawn slope is a picture only: this calculator does not size the slope or shoring; ≈ 12.2 yd³ gravel base · ≈ 18.9 tons; then the BASIS & WHAT WAS ASSUMED row and the link Check before you cut · Measure twice. 1 2 3 4 5
Steps 1 to 5 fill the inputs. The results update as you go.
  1. Enter LENGTH and WIDTH of the dig at the bottom of the cut. Include the working room outside the footing if you will dig it. The volume is figured with straight vertical sides.
  2. Enter DEPTH from existing grade to the bottom of the dig. The gravel base sits inside this depth, so measure to the underside of the gravel.
  3. Pick SOIL TYPE: Sand (12%), Loam (25%) or Clay (40%). The percent is the swell: how much the dirt grows once it is dug.
  4. Set TRUCK CAPACITY in cubic yards, from 1 to 20, to match the trucks you are hiring.
  5. Enter GRAVEL BASE DEPTH, the compacted thickness of stone over the whole footprint. Enter 0" for no gravel and the gravel line and the material list drop away.
  6. Read RESULTS. On the defaults: 10 truck loads, ≈ 88.9 yd³ bank · ≈ 111.1 yd³ loose, +25% swell — Loam (25%), Laid back 1-1/2:1 (OSHA, unclassified): ≈ 140.4 yd³ bank — not in the volume above, ≈ 12.2 yd³ gravel base · ≈ 18.9 tons.

Reading the results

Excavation scrolled to the drawing. The answer bar keeps 10 truck loads and ≈ 88.9 yd³ bank · ≈ 111.1 yd³ loose. The end of RESULTS shows ≈ 12.2 yd³ gravel base · ≈ 18.9 tons, the BASIS & WHAT WAS ASSUMED row and the link Check before you cut · Measure twice. The section drawing shows a 4' 0" DIG 20' 0" wide below GRADE 0", the 1-1/2:1 slope as a faint dashed line off the vertical side, and a spoil pile. Its notes read SECTION AREA = LOOSE VOL · 1.5:1 REPOSE SHOWN; SPOIL ≈ 111.1 CY LOOSE — LOAM (25%); 1-1/2:1 = OSHA MAX UNCLASSIFIED — NOT IN VOLUME; GRAVEL 6" TOP −3' 6" ≈12.2 CY ≈18.9 T +10%; 600 SF · 30' 0" INTO PAGE · PERIM 100' 0"; BANK ≈ 88.9 CY — NEAT LINE, VERTICAL SIDES; COMPETENT PERSON CLASSIFIES (APP. A): A 3/4:1, B 1:1; 10 LOADS @ 12.0 CY — LAST ≈ 3.1 CY; and UNDER 5' — COMPETENT PERSON TO CHECK FOR CAVE-IN, over the title strip EXCAVATION SECTION, 10 TRUCK LOADS, NOT TO SCALE. MATERIALS lists Gravel base (compacted) — 6" deep incl. ~10% over-dig/edge loss, 19.0 tons, above a dimmed SHARE PDF with a list icon at its right end, beside a lit SAVE. 7 10 11 12
The numbers match the list below.
  1. The headline is truck loads, rounded up to whole trucks. It is figured from the loose volume, not the bank volume.
  2. Bank and loose. Bank is the dirt as it sits in the ground: length by width by depth. Loose is bank plus the swell for your soil. Loose is what you haul and what you stockpile. The ≈ in front of a volume or a weight means the one decimal shown is rounded.
  3. Gravel base is in yards and tons. It carries an over-dig and edge-loss allowance. The material list row and the drawing note both say so: incl. ~10% over-dig/edge loss. The dirt volumes carry no allowance at all. The material list orders the tons up to the next tenth, the step a quarry ticket reads in: on the defaults 18.94 tons are needed, so it orders 19.0 tons, never less than the need.
  4. The drawing is a section across the width, with the spoil pile beside it. Pinch to zoom and use the expand button for full screen. See Drawings.
  5. The notes under the drawing are where you check what was assumed. BASIS & WHAT WAS ASSUMED states the swell for each soil, the gravel over-dig and the tons per cubic yard. The notes give the footprint area and perimeter, the bank volume with NEAT LINE, VERTICAL SIDES, the gravel thickness with the level of its top below grade, and the loads with how full the last truck is, here LAST ≈ 3.1 CY. The sloped sides drawn on the section are a picture only: the calculator does not size the slope or the shoring. They are drawn at 1-1/2:1, the steepest OSHA allows when the soil has not been classified (1926.652(b)(1)), for every soil type — SOIL TYPE sets the swell, not an OSHA soil type. A competent person classifies the soil on site (OSHA Subpart P, Appendix A); only then may a Type A soil stand at 3/4:1 or a Type B at 1:1. The notes read 1-1/2:1 = OSHA MAX UNCLASSIFIED — NOT IN VOLUME and COMPETENT PERSON CLASSIFIES (APP. A): A 3/4:1, B 1:1, and the spoil pile is drawn at least 2' back from the top of that slope (1926.651(j)(2)). The card adds the bank yards if you lay every side back at 1-1/2:1, and the cut sheet carries the same slope rule, with the picture-only sentence as its first result row, right under the drawing. A dig wider than 15' is an excavation, not a trench (1926.650(b)): the trench ladder rule is listed only for 15' or narrower.
  6. SLOPE OR SHORE PER OSHA 1926 SUBPART P appears in red once the dig is 5' or deeper, where OSHA 1926.652 requires a protective system. Shallower digs carry UNDER 5' — COMPETENT PERSON TO CHECK FOR CAVE-IN instead. Neither is a failed check, and the calculator does not classify your soil or size the slope.
  7. BASIS & WHAT WAS ASSUMED also carries two OSHA site rules: in a trench (15' wide or less) 4' or deeper a ladder, stair or ramp within 25' of travel for every worker (1926.651(c)(2)), and spoil and equipment kept at least 2' back from the edge (1926.651(j)(2)). A gravel base deeper than the dig is figured as a raised pad, and a line on the card says how far it stands above grade.
  8. Deeper than 20' the drawing reads OVER 20' — PE-DESIGNED SLOPE/SHORE PER OSHA SUBPART P and the results card carries a red ENGINEER REQUIRED — OVER 20' DEEP line. OSHA's slope and timber-shoring tables stop at 20' (Subpart P, Appendix B note 3 and Appendix C): past that the protective system is designed by a registered professional engineer, or you use a trench box within its maker's tabulated data. BASIS & WHAT WAS ASSUMED says so. The drawn slope is then labelled 1-1/2:1 DRAWN FOR REFERENCE — NOT IN VOLUME, and the classification note goes, since both rules apply only to 20' or less.
Excavation is a Pro calculator. SHARE PDF and SAVE are Pro as well, a one-time purchase. SHARE PDF and the list icon at its right end stay dim until you have entered your own measurements. SAVE stays lit, but until then a tap only answers Enter your job's numbers first and saves nothing.

Common mistakes