Inputs
Example data table
A realistic sample using three-day monitoring with downtime and filtering.
| Scenario | Total events | False events | Duration | Downtime | Sensors | Area | Gross rate (events/hr) | Events/shift (10h) |
|---|---|---|---|---|---|---|---|---|
| Laydown yard | 420 | 60 | 72 hours | 90 min | 8 | 2500 m2 | 5.9577 | 59.58 |
| Gate A | 180 | 15 | 24 hours | 0 min | 4 | 1200 m2 | 7.5000 | 75.00 |
Formula used
- Adjusted monitoring hours = Total hours − Downtime hours
- Verified events = Total events − False events
- Gross event rate (events/hour) = Total events ÷ Adjusted hours
- Verified event rate (events/hour) = Verified events ÷ Adjusted hours
- Events per sensor per hour = Total events ÷ (Adjusted hours × Sensors)
- Events per 1000 m2 per hour = Total events ÷ (Adjusted hours × Area/1000)
- Events per shift = Gross rate × Shift hours
- Estimated data per day (GB) = (Events/day × MB/event) ÷ 1024
- Effective verified rate = Verified rate × Confidence factor
How to use this calculator
- Enter the total motion events for a defined monitoring window.
- Select the duration unit that matches your log export.
- Include downtime so rates reflect true active monitoring time.
- Add false events if you review and classify triggers.
- Provide sensor count to normalize performance across devices.
- Optionally add monitored area to compare zones fairly.
- Use shift hours to estimate staffing or response workload.
- Export CSV or PDF to share with supervisors and auditors.
Article: Using motion event rate to manage site monitoring
1) Why event rate matters on active projects
Motion sensors and cameras create a measurable workload. A log that shows 6 events per hour produces about 60 clips in a 10-hour shift, affecting response time, supervisor reviews, and incident documentation. Tracking events per hour and events per shift turns raw triggers into staffing and review targets. Set weekly targets and review exceptions with stakeholders regularly.
2) Adjusting for downtime and partial coverage
Rates should be based on active monitoring time, not calendar time. If a 72-hour window includes 90 minutes of outage, adjusted hours drop to 70.5. The same 420 events then equal 5.96 events/hour instead of 5.83. This correction matters when comparing zones, weeks, or vendors.
3) Separating verified events from noise
False triggers often come from wind-moved tarps, dust, rain, welding arcs, or vehicle headlights. If 60 of 420 events are noise, the verified rate is 5.11 events/hour. Reporting the false-alarm share supports sensitivity tuning, masking, lighting upgrades, and more consistent incident evidence.
4) Normalizing by sensors and area
Normalization supports fair benchmarking. Events per sensor per hour highlights devices that over-trigger. Events per 1000 m2 per hour helps compare a 1,200 m2 gate zone to a 2,500 m2 laydown yard without misleading totals. Use these metrics to prioritize fixes where payback is fastest.
5) Linking events to storage and reporting
Storage planning improves when clip size is known. At 5.96 events/hour, a site generates about 143 events/day. With 3.2 MB per clip, that is roughly 0.45 GB/day, before overhead and retention copies. Exported CSV and PDF files support audits, trend reviews, and handovers.
FAQs
1) What is a motion event rate?
It is the number of motion triggers divided by active monitoring time, commonly reported as events per hour. It helps compare activity levels across zones, dates, and camera setups.
2) Why should I subtract downtime?
Downtime inflates performance by increasing the time window without capturing events. Using adjusted hours reflects true operating time and makes week-to-week benchmarks more reliable.
3) How do I estimate false events?
Review a sample of clips, classify noise triggers, and scale the share across the period. Common sources include weather, shadows, headlights, and moving equipment.
4) When should I use events per sensor?
Use it when comparing devices or vendors. A high per-sensor rate can indicate poor aim, sensitivity, or environmental interference on specific cameras.
5) What does events per 1000 m2 show?
It normalizes event activity by coverage area. This supports fair comparisons between small checkpoints and large yards, where raw event totals can be misleading.
6) How accurate is the storage estimate?
It is a planning estimate based on average clip size and events per day. Actual totals vary with bitrate, clip length, retention rules, and whether multiple streams are stored.
7) What is the confidence factor used for?
It applies a simple weight to the verified rate for planning. Use it to reflect review certainty or policy strictness when translating verified events into operational workload.