What Is Concrete Yield?

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Featured image with the headline What Is Concrete Yield, beside a grey round container holding fresh grey concrete on a plain wooden bench

You ordered 10 cubic yards, but the forms swallowed the whole load and still looked low. Did the plant short you, or did the job eat more than you planned? Yield is how you tell those two stories apart.

Quick Answer

Concrete yield is the volume of fresh concrete a batch actually makes. ASTM C138 finds it by weighing concrete in a measured container to get unit weight, then dividing the total batch weight by that unit weight. Relative yield compares the volume obtained with the volume ordered.

What Concrete Yield Really Means

Yield is the fresh volume a batch of concrete produces, measured the moment it leaves the mixer. Ready-mix is sold by that fresh volume, not by weight, under ASTM C94. So a “yard” of concrete is a yard of plastic, workable material before it sets.

The number matters because concrete is paid for by volume but batched by weight. The plant weighs cement, water, sand, stone and admixture into the drum. Yield is the bridge that turns those pounds back into cubic yards. A bagged mix is rated the same way: one 80 lb bag of QUIKRETE Concrete Mix makes about 0.60 cubic feet of fresh concrete.

Our concrete yield calculator does this bridge for you. You enter the ingredient weights and the measured density, and it returns the yield and the relative yield per ASTM C138.

How ASTM C138 Measures Unit Weight and Yield

ASTM C138 is the Standard Test Method for Density (Unit Weight), Yield, and Air Content of Concrete. It starts with unit weight: fill a container of known volume with fresh concrete, weigh the concrete alone, and divide by the container volume.

Take a 0.25 cubic foot measure holding 36.25 pounds of concrete. The unit weight is 36.25 / 0.25, which is 145.0 pounds per cubic foot. Normalweight concrete usually lands between 140 and 150 pounds per cubic foot, so that reading looks right.

Yield then follows from one division. The total batch weight is the sum of every ingredient on the batch ticket. Divide that weight by the unit weight for cubic feet, or by the unit weight times 27 for cubic yards, since one cubic yard is exactly 27 cubic feet.

  1. Add the ticket. Suppose the batch ticket totals 15,500 pounds of cement, water, sand, stone and admixture.
  2. Divide by unit weight. 15,500 / 145 is 106.9 cubic feet of fresh concrete.
  3. Turn feet into yards. 106.9 / 27 is 3.96 cubic yards. The same math in one step is 15,500 / (145 x 27), which is 15,500 / 3,915, or 3.96 cubic yards.
The concrete yield formula A left to right flow. The first box is the total batch weight of 15,500 pounds. It is divided by the second box, the unit weight of 145 pounds per cubic foot. The result is 106.9 cubic feet of fresh concrete, which equals 3.96 cubic yards because one cubic yard is 27 cubic feet. Batch weight divided by unit weight is yield Total batch weight 15,500 lb / Unit weight 145 lb/ft3 = 106.9 cu ft = 3.96 cu yd One cubic yard is exactly 27 cubic feet, so 106.9 / 27 is 3.96 cubic yards. The tool default: 4,050 lb / 150 lb/ft3 is 27 cu ft, which is 1.00 cubic yard.
Yield turns the pounds on the batch ticket back into cubic yards.

Reading Relative Yield: On Target, Short, or Over

Relative yield is the ratio of the volume you actually obtained to the volume the batch was designed for. A value of 1.00 means the load delivered exactly what was ordered. Above 1.00 is an over-yield, and below 1.00 is a short yield.

Work an example. The plant designed a 10.0 cubic yard batch, but the C138 math shows only 9.8 cubic yards of fresh concrete. Relative yield is 9.8 / 10.0, which is 0.98. That load ran 2 percent short. The tool’s default batch, 4,050 pounds at 150 pounds per cubic foot, yields 27 cubic feet, or 1.00 cubic yard, against a designed 1.00, so its relative yield reads 1.00 and “On target”.

How to read a relative yield value
Relative yield What it means What to check
0.97 Short yield: you got about 3 percent less volume than designed Slab thickness, subgrade, form movement and waste before blaming the plant
1.00 On target: the delivered volume matched the design Nothing; the batch met its design volume
1.03 Over-yield: about 3 percent more volume than designed Air content and aggregate, since too much air can read as extra volume
Relative yield as plain bars Three horizontal bars compared against a dashed vertical line at a relative yield of 1.00. The top bar is 0.98, a short yield. The middle bar is 1.00, on target. The bottom bar is 1.02, an over-yield. Each bar length is drawn in proportion to its value on a scale from zero to 1.10. Relative yield against a 1.00 target 1.00 target 0.98 short yield (2 percent low) 1.00 on target 1.02 over-yield (2 percent high)
Relative yield is a volume check, so it says nothing about strength.

Why a Load Comes Up Short or Long on Site

Most apparent shortages are a job problem, not a plant problem. NRMCA guidance in CIP 8 explains that small errors in placement move far more volume than people expect.

A thin slab is the usual culprit. CIP 8 notes that a 1/8 inch error in a 4 inch slab means a shortage of 3 percent, or 1 cubic yard in a 32 cubic yard order. Form deflection, an irregular subgrade, settlement and spillage all add to that. The load was not short; the forms simply held more concrete than the drawing said.

An over-yield has its own warning. CIP 8 says excess concrete “can be an indication of a problem if the excess concrete is caused by too much air or aggregate.” So a relative yield above 1.00 is not always free concrete.

Where the missing yard went A single bar for a 32 cubic yard order. Thirty one cubic yards go into the slab. The remaining 1 cubic yard, about 3 percent, is the apparent shortage caused by pouring a 4 inch slab one eighth inch too thick. Other listed causes are form deflection, a soft subgrade, settlement and spillage. A 1/8 inch over-thick 4 inch slab eats a yard 31 cu yd placed in the slab 1 cu yd 3 percent 32 cu yd ordered Other causes that move volume without a short load: form deflection, an irregular subgrade, settlement, and spillage or waste. Over-yield can signal too much air or aggregate, not bonus concrete.
Check the slab before you call the yield short.

The Fresh-to-Hardened Gap and How Much Extra to Order

Fresh concrete shrinks a little as it sets. CIP 8 notes that hardened concrete “may be about 2 percent less than its volume in a freshly mixed state.” So the yard you measure at the chute is slightly more than the hard yard you measure a month later.

Plan for loss on top of that. CIP 8 advises ordering 4 to 10 percent extra to cover waste, spillage and the odd low spot. That buffer is why a job that needs 9.5 yards on paper might order 10. For the volume your project needs before the buffer, use our concrete volume calculator, and to size the delivery itself, see the concrete truck calculator.

Yield is not strength. A load can hit a perfect 1.00 relative yield and still fail a cylinder break, because yield measures volume and strength is a separate test. To check strength, read our guide to the concrete cylinder test.

Averaging Three Trucks for a Fair Check

One unit-weight test is a snapshot, not a verdict. CIP 8 recommends basing a yield check on the average of three unit-weight tests, each taken from a different truck. A single truck can read high or low for reasons that even out across the delivery.

This matters most on a disputed load. A single 0.98 reading is not proof of a short order, since the next two trucks might read 1.01 and 1.00. Bagged jobs rarely need any of this. A bag states its yield on the label, and bagged mixes grow impractical past about one cubic yard, where ready-mix takes over. Our guide to ready-mix versus bagged concrete covers that crossover.

Check your own batch

Enter your ingredient weights, measured density and designed volume in the yield and relative yield tool to get both numbers in one step.

FAQs About Concrete Yield

What does concrete yield mean?

Concrete yield is the volume of fresh concrete a batch actually makes, measured as it leaves the mixer. Ready-mix is sold by this fresh volume under ASTM C94, not by weight, so yield turns batch pounds into cubic yards.

How do you calculate concrete yield?

Divide the total batch weight by the concrete’s unit weight. For cubic yards, divide by the unit weight times 27. A 15,500 pound batch at 145 pounds per cubic foot is 15,500 / (145 x 27), which is 3.96 cubic yards.

What is a good relative yield?

A relative yield of 1.00 is the target, meaning the delivered volume matched what was designed. Values below 1.00 are short yields, and values above 1.00 are over-yields. Small swings often trace to the slab, not the plant.

Does a low concrete yield mean weak concrete?

No. Relative yield is a volume check, not a strength check. A load can read a perfect 1.00 and still fail a cylinder break, because strength is measured separately. Yield only tells you how much fresh volume you received.

Why did my concrete come up short?

Usually the slab held more than the drawing said. A 1/8 inch error in a 4 inch slab is a 3 percent shortage, about 1 yard in a 32 yard order. Form deflection, soft subgrade and spillage add more.

How much extra concrete should I order?

Order 4 to 10 percent extra to cover waste, spillage and low spots, as NRMCA CIP 8 advises. Fresh concrete also shrinks about 2 percent as it hardens, so the buffer protects against running short on site.

How many unit weight tests should I run for yield?

Base a yield check on the average of three unit-weight tests, each from a different truck, as CIP 8 recommends. One truck can read high or low for reasons that even out across the full delivery.

Sources and Further Reading

References Used in This Article

This article explains concrete yield as defined by ASTM C138 and NRMCA CIP 8. Relative yield is a volume check, not a strength check, so a load that meets its design volume can still need a separate cylinder test. Reviewed for accuracy by Prof. Dr. Khalil Mudassar, PhD. Last updated 2026-11-07.