Enter Project Inputs
Example Data Table
| Scenario | Inbound trucks/day | Outbound trucks/day | Hours/day | Turn time (min) | Peak factor | Utilization | Redundancy | Estimated doors |
|---|---|---|---|---|---|---|---|---|
| Baseline warehouse | 24 | 30 | 16 | 45 | 1.25 | 75% | 10% | 4 |
| Peak season | 35 | 45 | 18 | 50 | 1.40 | 70% | 15% | 7 |
| High velocity operations | 20 | 24 | 20 | 30 | 1.15 | 80% | 5% | 3 |
Formula Used
This calculator sizes doors by comparing daily truck demand to the effective daily capacity of one door.
- Moves per door per day = (Operating hours × 60) ÷ Turn time
- Effective capacity per door = Moves per day × Utilization
- Adjusted demand = Daily trucks × Peak factor
- Required doors = CEILING((Adjusted demand ÷ Capacity per door) × (1 + Redundancy))
How to Use This Calculator
- Enter inbound and outbound trucks expected per day.
- Select shared doors or dedicated inbound/outbound doors.
- Use realistic turn times from time studies or logs.
- Set operating hours when doors are actively serviced.
- Apply a peak factor for surge days and seasonality.
- Choose a utilization target to control waiting and risk.
- Add redundancy for maintenance, failures, or constraints.
- Press calculate and review the total doors and notes.
- Export CSV or PDF to share planning assumptions.
Demand profiling for dock doors
Dock door quantity planning starts with daily truck demand split into inbound receiving and outbound shipping. Capture averages, the highest consistent surge days, and the inbound-to-outbound ratio by shift. Use appointment data, gate logs, and seasonal forecasts to avoid undersizing doors during promotions or harvest cycles.
Turn time drivers and dwell reduction
Turn time is the strongest driver of door capacity. Include check-in, spotting, loading or unloading, paperwork, and departure. Long dwell often comes from staging congestion, labor gaps, or delayed documents. Improvements like pre-staging, clear call-up rules, and yard support can cut minutes per move. Reducing dwell by even 10 minutes can increase capacity without adding doors.
Capacity modeling and utilization targets
This calculator converts operating hours into moves per door, then applies a utilization target to preserve service quality. Account for breaks, changeovers, and inspections when setting usable service time. Lower utilization protects against randomness, rework, and late arrivals. Many sites plan within 65–85% depending on service expectations and detention risk.
Peak factor and redundancy planning
Peak factor scales average demand to a design day, reflecting weekly spikes and seasonal surges. Redundancy adds resilience for maintenance, blocked doors, safety holds, and equipment downtime. When reliability is uncertain, add redundancy before raising utilization, because higher utilization magnifies queues during variability.
Example data and interpretation
Example scenario: 24 inbound trucks/day, 30 outbound trucks/day, 16 operating hours, 45 minute average turn time, 75% utilization, 1.25 peak factor, and 10% redundancy. The estimated requirement is 4 total doors. Peak season scenario: 35 inbound, 45 outbound, 18 hours, 50 minutes, 70% utilization, 1.40 peak factor, and 15% redundancy yields about 7 doors. Use dedicated mode when turn times differ, then review staffing and yard capacity. Export results to document assumptions for review.
FAQs
1) What turn time should I use?
Use the average from dock logs or time studies. Include check-in, spotting, loading or unloading, paperwork, and departure. Use separate inbound and outbound times when processes differ.
2) Why not target 100% utilization?
At 100% utilization, small delays create long queues. A lower target keeps buffer for variability, rework, late arrivals, and equipment issues. Many plans use 65–85% depending on service expectations.
3) How do I choose a peak factor?
Peak factor is peak-day trucks divided by average-day trucks. Use history by season and shift. Start around 1.15–1.40, then stress test with worst weeks and carrier variability.
4) What does redundancy represent?
Redundancy adds spare capacity for door downtime, blocked positions, maintenance, and labor shortfalls. Typical planning allowances are 5–15%, increasing when reliability is low or congestion is frequent.
5) When should I use dedicated mode?
Use dedicated mode when inbound and outbound are separated, require different equipment, or run on different schedules. It sizes each flow independently and avoids one side masking shortages on the other.
6) Does this include staging space constraints?
No. Confirm yard, staging lanes, door spacing, forklift capacity, and labor plans can support the throughput. Door quantity alone cannot prevent congestion if upstream areas are constrained.
7) How should I validate the result?
Run multiple scenarios, compare with observed queues and dwell times, and adjust assumptions. If queues persist, reduce utilization or increase peak factor and redundancy. For critical sites, validate with a simple simulation.