Plan Every Batch Before Mixing Starts
Estimate usable mixer capacity, batches required, bags per batch, cubic yards per hour and total mixing time for portable drum mixers and small jobsite concrete mixing operations.
Choose a calculation method to estimate usable batch size, batch count, bags per load or hourly mixer output.
Convert rated drum volume into estimated usable batch volume using a selected usable-fill factor.
Use manufacturer's rated batch capacity when available
This is a planning estimate. Do not exceed the mixer's manufacturer-rated mixing or batch capacity.
Estimate how many mixer batches are required for a known concrete project volume.
Estimate how many 40 lb, 60 lb or 80 lb concrete bags fit within the usable mixer batch volume.
Bag yields are approximate generic values. Verify the actual product label and mixer instructions before loading.
Estimate realistic concrete production per hour from usable batch size and cycle time.
Actual production depends on loading, water measurement, mixing time, discharge, crew, access, cleanup and equipment performance.
Convert rated drum size into a realistic working batch volume.
Estimate how many mixer loads are required for the full concrete quantity.
Match bag yield to usable mixer capacity without overfilling the drum.
Estimate production speed from batch size, cycle time and efficiency.
The Concrete Mixer Capacity Calculator helps plan portable or small jobsite mixing after the required concrete quantity is known. Start with the mixer's rated batch capacity whenever the manufacturer provides one. If you only know total drum volume, the first panel can apply a usable-fill factor for planning.
Next, compare usable batch volume with the concrete required for your slab, footing, post base, steps or other project. The Batch Count calculator rounds partial batches up so you know how many mixing cycles are needed. If using bagged concrete, the Bags per Batch panel compares mixer volume with approximate bag yield.
Use the manufacturer's rated mixing volume.
Calculate the total concrete required for the project.
Enter the usable concrete output per mixer load.
View batches, bags and estimated production rate.
Coordinate loading, placement, finishing and cleanup.
Mixer capacity can be described in gallons, cubic feet, liters or cubic meters. Because a mixer usually needs open space for tumbling and blending, the full geometric drum volume should not automatically be treated as usable concrete output.
Use this only when an actual manufacturer-rated batch output is not available.
May be listed in ft³, gallons or liters.
Allows room for materials to tumble during mixing.
The value used for batch count and production calculations.
Mixer specifications are not always listed in the same units. The table below gives simple volume conversions for planning. These figures describe volume only; they do not indicate whether the entire volume is usable for mixing.
| Volume | Cubic Feet | U.S. Gallons | Liters | Cubic Yards |
|---|---|---|---|---|
| 1 ft³ | 1.00 | 7.48 gal | 28.32 L | 0.037 yd³ |
| 2 ft³ | 2.00 | 14.96 gal | 56.63 L | 0.074 yd³ |
| 3 ft³ | 3.00 | 22.44 gal | 84.95 L | 0.111 yd³ |
| 4 ft³ | 4.00 | 29.92 gal | 113.27 L | 0.148 yd³ |
| 5 ft³ | 5.00 | 37.40 gal | 141.58 L | 0.185 yd³ |
| 6 ft³ | 6.00 | 44.88 gal | 169.90 L | 0.222 yd³ |
Batch count is one of the most practical mixer calculations. Divide the total concrete volume by the usable batch output and round up. If the last batch is only partly full, it still counts as a mixing cycle.
Apply any concrete ordering or planning allowance before calculating the final batch count.
Bagged concrete is normally sold by bag weight, but the mixer must be planned by concrete volume. A bag label provides approximate cured or mixed yield. Divide the usable mixer capacity by that yield and round down to a whole number so the theoretical batch does not exceed the selected capacity.
| Bag Size | Approx. Yield Used | 3 ft³ Mixer Batch | 4 ft³ Mixer Batch | 5 ft³ Mixer Batch |
|---|---|---|---|---|
| 40 lb | 0.30 ft³ | 10 bags | 13 bags | 16 bags |
| 60 lb | 0.45 ft³ | 6 bags | 8 bags | 11 bags |
| 80 lb | 0.60 ft³ | 5 bags | 6 bags | 8 bags |
Mixer productivity is not simply batch volume multiplied by a perfect number of cycles. Every batch takes time to load, add water, mix, discharge, move concrete and reset the equipment. The calculator uses cycle time and an operating-efficiency factor to produce a more practical planning rate.
Convert cubic feet per hour to cubic yards per hour by dividing by 27.
An 80% efficiency factor means the crew achieves about 80% of the theoretical continuous production rate. Interruptions can include material handling, repositioning, wheelbarrow travel, water measurement and cleanup.
Suppose a mixer produces 3 ft³ per usable batch and the full load-mix-discharge cycle takes 8 minutes. The theoretical maximum is 60 ÷ 8 = 7.5 cycles per hour. At 3 ft³ per cycle, that equals 22.5 ft³ per hour.
At that rate, a 2 cubic yard project would require around three hours of active production, not including form setup, reinforcement, finishing or extended interruptions.
Small portable mixers are useful when the project is too large for mixing by hand but too small or inaccessible for practical ready-mix delivery. Mixer choice should consider usable batch capacity, power source, loading height, mobility, discharge method and how quickly the crew can place each load.
Useful for post footings, repairs, steps and limited pours.
Can reduce batch count when the crew can load, discharge and place larger volumes efficiently.
Portable mixing is not automatically cheaper or faster. For larger continuous slabs or driveways, dozens of mixer cycles can create placement delays and inconsistent finishing conditions. Ready-mix delivery can place large volumes much faster when truck or pump access is available.
The best mixer capacity depends on the total concrete quantity and the rate at which the crew can place and finish the material. Use the project's dedicated volume calculator first, then bring the result into the batch-count tool.
| Project | First Calculation | Mixer Planning | Related Tool |
|---|---|---|---|
| Slab | Length × width × thickness | Volume ÷ usable batch | Concrete Slab Calculator |
| Footing | Footing volume | Multiple small batches may be practical | Concrete Footing Calculator |
| Post / Pier | Round volume | Batch by pier group | Concrete Post Calculator |
| Stairs | Stepped volume | Check placement continuity | Concrete Stair Calculator |
| General Project | Total concrete volume | Batch count and hourly production | Concrete Calculator |
A realistic cycle time starts before the drum turns and ends after the concrete is discharged. If the crew must carry bags, measure water, move wheelbarrows or clean the discharge area between loads, those activities affect output.
Concrete mixers combine rotating equipment, heavy materials, wet concrete, electricity or fuel and repetitive manual handling. Follow the equipment manufacturer instructions, use guards as designed and keep hands, tools and loose clothing away from moving components. Wet concrete can also cause skin and eye injuries.
See how drum size becomes usable batch volume, then batch count and hourly production.
Answers about mixer size, usable batch capacity, concrete bags, batch count and hourly output.