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The total mass of the measuring container filled with consolidated concrete.
Weigh on a calibrated scale immediately after consolidating the sample per ASTM C138.
The mass of the empty measuring container.
Weigh the clean, dry, empty measure before filling it.
The calibrated volume of the measuring container.
A standard ASTM C138 unit weight measure is commonly 7 L (0.25 ft³) for aggregates up to 1 in, or larger for bigger aggregate.
Unit weight
158.2 pcf
- Net concrete mass
- 37 lb
- Equivalent in pcf
- 158.16 pcf
They open the calculator with your figures already in it
Concrete Unit Weight (Density) Calculator (ASTM C138): 158 pcf — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- ASTM C138 unit weight test: unit weight = (mass of measure filled with concrete - mass of empty measure) / volume of the measure
Inputs used
- Mass of Measure + Concrete
- 55 lb
- Mass of Empty Measure
- 18 lb
- Measure Volume
- 1.75 gal
Intermediate steps
- Net concrete mass
- 37 lb
- Equivalent in pcf
- 158.16 pcf
What this calculation does not cover
- Unit weight is a density measurement, not an air-content test. It cannot separate entrained and entrapped air from the rest of the volume unless you already know the mix's theoretical air-free density, so it does not replace a pressure or volumetric air meter.
- The calculation treats the measure's stated volume as exact. It makes no allowance for a measure that has not been water-calibrated, one that is dented or out of round, or for how the sample was consolidated and struck off — under-rodding leaves voids that read back as low density, and none of that is visible in the arithmetic.
- This is the fresh, plastic density at the point of sampling. It is not the hardened in-service density used for dead-load calculations, which is lower once free water leaves the concrete; for lightweight mixes the equilibrium density is a separate determination.
- One sample, no verdict. The calculator does not compare the result against a design or specified density, apply an acceptance tolerance, or account for where in the load the sample was taken or how long after batching it was drawn.
- The measure volume field is capped at 30 L (about 1 cubic foot). A larger measure — the size used where the nominal maximum aggregate is oversize — cannot be entered; the value is clamped to the cap, which computes the density against a volume you did not enter.
Add the equipment this sizes
This result is a specification — 158.2 pcf — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-02 · in the site-wide review of 2026-09-06 · v1.2.1
Regulatory standards & verification citations1
- ASTM C138 unit weight test: unit weight = (mass of measure filled with concrete - mass of empty measure) / volume of the measure
Which documents these citations point at
Standards referenced: ASTM C138 (ASTM International, United States).
Cite this page
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