OnSumoTools

Concrete Yield Calculator

Calculate how many bags of concrete mix or cubic yards of ready-mix you need for slabs, walls, footings, and columns, with waste and cost included.

100% client-side. Inputs stay in your browser (ons-concrete-yield-inputs).

Bag yields follow common retail mix labels (0.30, 0.45, and 0.60 cu ft per bag). Your brand may differ; buy one extra bag on tight pours.

Bags needed

62 bags

Estimated cost

$341.00

Volume with waste

36.67 cu ft

Sections

Mix and pricing

SectionShapecu ftcu yd
Main slabSlab33.331.23
Total (valid sections)33.331.23
With 10% waste36.671.36
Order quantity
62 bags
Estimated cost
$341.00
Raw volume
33.33 cu ft (1.23 yd)
Mix
80 lb bags

How does the Concrete Yield Calculator work step by step?

Input the batch quantities for each component: cement (bags or pounds), water (gallons or pounds), coarse aggregate (pounds or cubic feet), fine aggregate (pounds or cubic feet), and any admixtures or supplementary cementitious materials. Enter the specific gravity for each material (cement is typically 3.15, aggregates range from 2.60 to 2.75, water is 1.0). The calculator computes the absolute volume of each material (weight divided by specific gravity and unit weight of water) and sums them to determine theoretical yield in cubic yards or cubic feet.

What does a typical Concrete Yield Calculator result look like?

A 10 by 10 foot patio slab at 4 inches thick is about 33 cubic feet, or 1.2 cubic yards before waste. With 10% waste you need roughly 37 cubic feet. That is about 62 eighty-pound bags, or about 1.4 yards from a ready-mix truck if you switch mix type in the tool.

Frequently asked questions

  • Why is my concrete yield consistently below 100 percent?

    Common causes include dry aggregates absorbing mix water (reduce yield by 2 to 5 percent if aggregate moisture is not corrected), excess entrained air (each 1 percent of air reduces yield by roughly 1 percent), or under-batching of coarse aggregate due to scale calibration errors. Check aggregate moisture content and apply corrections to water and aggregate weights. Verify air content with a pressure or volumetric air meter and adjust air-entraining admixture dosage to target. Recalibrate batching scales monthly to prevent drift.

  • How does aggregate moisture affect concrete yield?

    Wet aggregates carry surface moisture that contributes to mix water, increasing yield. Dry aggregates absorb water, reducing free water available for workability and yield. If aggregates contain 5 percent moisture by weight and you batch 1,000 pounds of aggregate, 50 pounds is water. If the mix design assumes dry aggregate, you must reduce added water by 50 pounds to maintain correct water-cement ratio and yield. Most batching systems adjust water automatically based on real-time moisture sensors on aggregate bins.

  • Can I adjust my mix design to increase yield without reducing quality?

    Yes, within limits. Increasing the proportion of fine aggregate (sand) slightly can increase yield, but excessive sand reduces workability and may lower strength. Optimizing aggregate gradation to minimize voids increases packing density and yield without adding cement. Reducing air content to the minimum needed for freeze-thaw durability (4 to 6 percent for most applications) maximizes solid volume and yield. Do not add water to increase yield, as this reduces strength and durability by increasing the water-cement ratio.

  • What is the acceptable yield range for structural concrete?

    Most specifications and quality standards accept yield between 98 and 102 percent. Yield below 98 percent may indicate material shortages or quality issues and typically requires investigation. Yield above 102 percent suggests excess water, over-sanding, or aggregate bulking and should also be investigated. For high-strength or specialty concrete, tighter yield tolerances (99 to 101 percent) ensure consistency and compliance with engineered mix designs.

  • How do admixtures affect concrete yield?

    Most liquid admixtures (water reducers, retarders, accelerators) are dosed at 2 to 10 ounces per hundredweight of cement and contribute negligible volume, so they have minimal impact on yield. Air-entraining admixtures increase air content by 4 to 8 percent, which reduces solid volume and yield proportionally. Supplementary cementitious materials (fly ash, slag, silica fume) replace a portion of cement on an equal-volume or equal-weight basis and affect yield based on their specific gravity relative to cement. Calculate absolute volume for each component to account for density differences.

  • How often should I verify concrete yield on a production plant?

    Daily yield tracking on at least one representative batch per truck or shift detects issues early. Monthly calibration of batching scales and moisture sensors ensures long-term accuracy. Investigate immediately if yield deviates more than 2 percent from target or if customers report short loads. Seasonal changes in aggregate moisture (wet in spring, dry in summer) require periodic re-verification of moisture corrections and yield.

Related tools

How much concrete do you need?

Ordering too little means a cold joint and a second delivery fee. Ordering too much wastes money and leaves you with a truckload to dump. A few minutes of math up front avoids both.

The calculator handles slabs, walls, footings and columns, and you can add several sections to one job. It sums the volume and shows it in cubic yards and cubic meters.

Bags or ready-mix

For small jobs, bags are practical. An 80 pound bag makes about 0.6 cubic feet, so a cubic yard takes roughly 45 of them. Past a couple of yards, ready-mix by truck is usually cheaper and much less back-breaking.

The tool gives you both counts so you can compare. It also adds a waste allowance and a cost estimate from your local price.

Always add a cushion

Ground is never perfectly flat, forms bow a little, and some mix stays in the truck or wheelbarrow. Add 5 to 10 percent. Go toward 10 for rough, uneven ground.

Check your forms before the truck arrives. Measuring twice is quick. Fixing a short pour is not.

Your numbers stay in your browser.