A ready-mix order can require several delivery loads, but a generic drum size cannot tell you the final count. The usable quantity can change with the scheduled vehicle, mixture, route, weight limits and producer plan.
Begin with the confirmed order volume. Ask the producer for the usable capacity assigned to each load, then calculate an illustrative split and send it back for dispatch confirmation.
How many ready-mix concrete truck loads do you need?
Divide the confirmed order volume by the supplier-stated usable capacity per dispatched load and round the ratio upward. The result is a delivery-load count, not necessarily the number of unique physical trucks.
Exact load ratio = confirmed order volume ÷ confirmed usable capacity per load
Illustrative delivery loads = ceiling(exact load ratio)
Rated drum volume, a published regional range and legal maximum weight do not prove how much this producer will dispatch on this vehicle, route and mixture.
The Ready-Mix Concrete Calculator accepts a supplier-stated capacity as an optional planning input.
What does “truck capacity” mean in this calculation?
It means the usable concrete volume that the producer confirms for one scheduled load. Record the unit, mixture, vehicle or fleet basis, route, source, date and person who confirmed it.
| Term | Meaning | Use as the calculator input? |
|---|---|---|
| Rated drum capacity | Equipment rating or nominal drum volume | No, unless the producer confirms it as usable load volume |
| Usable dispatched capacity | Volume planned for this delivery basis | Yes |
| Legal payload | Weight allowed under applicable vehicle and route rules | No direct volume conversion without producer data |
| Commercial full-load threshold | Pricing or fee term | No |
| Ticketed quantity | Quantity shown for an actual load | Use later for reconciliation |
NRMCA CIP 31 states that truck mixer capacities vary and tells purchasers to communicate quantity, delivery rate, placement duration and access. Its capacity range describes industry context; it does not assign a capacity to this order.
Worked example: full loads and a final partial load
A confirmed order is 18.4 yd³. The producer confirms 8 yd³ as the usable capacity for every planned load in this example.
- Exact ratio: 18.4 ÷ 8 = 2.3 loads.
- Illustrative load count: ceiling(2.3) = 3 loads.
- First 2 loads at the stated capacity: 2 × 8 = 16 yd³.
- Illustrative final load: 18.4 - 16 = 2.4 yd³.
- Nominal capacity across 3 loads: 3 × 8 = 24 yd³.
- Unused nominal capacity: 24 - 18.4 = 5.6 yd³.
The 5.6 yd³ is empty planning capacity. It is not automatically produced, delivered, billed, returned or available as surplus concrete.
| Load | Planned volume | Running total |
|---|---|---|
| 1 | 8.0 yd³ | 8.0 yd³ |
| 2 | 8.0 yd³ | 16.0 yd³ |
| 3 | 2.4 yd³ | 18.4 yd³ |
The producer may approve another allocation across the same 3 loads. The table is an arithmetic check, not dispatch instruction.
What happens when the order is an exact multiple?
The final load equals the full usable capacity. It should not be reported as zero.
For a 16 yd³ order and 8 yd³ usable capacity, the count is 2. The final-load formula gives `16 - 8 × (2 - 1) = 8 yd³`.
Illustrative final load = order volume - capacity × (load count - 1)
How do you plan loads when capacities differ?
Use the scheduled capacity of each load in sequence and stop when cumulative capacity reaches the order. A single average can hide an inadequate early plan.
An 18 yd³ order has scheduled usable capacities of 7.5, 8 and 6 yd³:
| Load | Scheduled usable capacity | Cumulative capacity | Illustrative allocation |
|---|---|---|---|
| 1 | 7.5 yd³ | 7.5 yd³ | 7.5 yd³ |
| 2 | 8.0 yd³ | 15.5 yd³ | 8.0 yd³ |
| 3 | 6.0 yd³ | 21.5 yd³ | 2.5 yd³ |
Two loads provide only 15.5 yd³, so a third is required. The scheduled set has 3.5 yd³ of unused nominal capacity. Confirm the actual allocation and commercial treatment with the producer.
Are delivery loads the same as the number of trucks?
No. A load is one delivery trip or dispatch record. One physical truck may make several trips, while several trucks may each carry one load.
| Possible plan | Delivery loads | Unique vehicles | What must be confirmed |
|---|---|---|---|
| One trip per vehicle | 4 | 4 | Fleet assignment and arrival plan |
| Two trips per vehicle | 4 | 2 | Plant, travel, discharge and return cycle |
| Mixed trips | 4 | Producer-selected | Availability, capacities and dispatch sequence |
Vehicle count cannot be derived from load count alone. It needs plant cycle time, travel, site discharge, return, cleaning, fleet availability and the producer's schedule.
Which inputs should be confirmed before using the load count?
- Final supplier-confirmed order quantity and unit.
- Approved mix code for each quantity group.
- Usable capacity for every scheduled load or fleet class.
- Whether a final partial load is available.
- Minimum delivered quantity, short-load fee and invoice terms as separate fields.
- Site access and approved discharge or conveying method.
- Required start time, placement rate, truck spacing and duration.
- Contacts for add-on orders, stoppages, breakdowns and changes.
The NRMCA and ASCC order checklist records quantity, truck spacing or duration, placement rate, access and emergency contacts. The producer and placement team must turn those fields into the actual schedule.
How should planned loads be tracked?
Keep planned and actual load states separate. This makes a cancellation, substitution, capacity change or returned quantity visible.
| State | Record |
|---|---|
| Planned | Load ID, mix code, usable capacity and planned quantity |
| Scheduled | Vehicle or fleet class, plant, dispatch slot and contacts |
| Batched | Producer batch and ticket reference |
| Dispatched | Departure record and destination |
| Arrived | Site arrival and acceptance check |
| Discharged | Quantity record and placement destination |
| Returned, redirected or cancelled | Quantity, reason, time and approval |
NRMCA's quality-system guidance includes order entry, dispatch, batch instructions, recordkeeping, truck tracking and site control. Each producer's current procedure governs its records.
Myth versus reality
| Myth | Reality |
|---|---|
| Every mixer carries the same volume | Use the producer-confirmed usable capacity for the scheduled load. |
| Three loads means three trucks | It means three delivery trips or dispatch records; vehicle assignment may differ. |
| Unused capacity is surplus concrete | It is arithmetic capacity unless concrete is actually ordered and produced. |
| A partial final load changes the project geometry | It changes the delivery split, not measured or ordered volume. |
| An average capacity works for a mixed fleet | Check cumulative scheduled capacities in sequence. |
Common truck-load planning mistakes
- Using a universal capacity.
- Entering rated drum volume without producer confirmation.
- Calling delivery loads “trucks needed.”
- Reporting zero for an exact-multiple final load.
- Treating unused nominal capacity as delivered surplus.
- Averaging a mixed fleet without checking cumulative capacity.
- Combining different mix codes in one split.
- Using load count as an access or payload approval.
- Ignoring partial-load availability and commercial terms.
- Presenting an arithmetic split as a confirmed dispatch schedule.
Prepare the order first with the Ready-Mix Cubic-Yard Ordering guide. Return to the Concrete Planning hub for related workflows.
Safety and scope limits
This page does not approve a vehicle, payload, axle weight, route, bridge, grade, turning path, ground support, access point, pump, chute or traffic plan. Use applicable law, producer controls, project requirements and qualified site personnel.
NRMCA notes that a loaded concrete truck is heavy and may not manoeuvre over loose ground, residential curbs or pathways. Confirm access and alternative placement methods before dispatch.
Sources and source scope
- NRMCA CIP 31, Ordering Ready Mixed Concrete: capacity variation, scheduling, access and purchaser communication.
- NRMCA and ASCC Checklist for Ordering and Scheduling Ready Mixed Concrete: order, spacing, placement-rate, access and contact fields.
- NRMCA Quality Management System for Ready Mixed Concrete Companies: producer order, dispatch, recordkeeping and truck-tracking process context.
- NIST Guide to the SI Appendix B: unit conversions.
Source scope: NRMCA supports the ordering and producer-process context. NIST supports unit arithmetic. None assigns the usable capacity, vehicle count, load allocation, route, fee or schedule for a specific order.
