Chapter 9: Calculator

Five interactive real-time calculators for LPR/ANPR system design

These calculators provide real-time computation of key LPR/ANPR system design parameters. Enter your specific values to instantly see results, helping you make precise engineering decisions without manual calculation. All formulas are based on established optical and networking engineering principles.

📷 Lens Focal Length Calculator

Calculate the required lens focal length to achieve the minimum plate pixel width at your capture distance. Adjust parameters to see real-time results.

8m
Horizontal distance from camera to plate capture point
140 px
140px = standard recognition; 200px+ = high accuracy
Standard: EU 520mm, US 305mm, CN 440mm
1/2.8"=5.37, 1/2"=6.40, 1/1.8"=7.18, 1/1.2"=8.80
Megapixels (e.g., 2, 5, 8, 12)
Calculation Results
—Required Focal Length
—Horizontal FoV
—Plate Pixel Width
Status: —
Plate pixel coverage vs. requirement
Formula: Focal Length (mm) = Sensor Width (mm) × Distance (m) × 1000 ÷ Plate Width (mm)
Plate Pixels: Plate Width (mm) ÷ (FoV_m × 1000 ÷ Sensor_Pixels)
Guideline: Standard recognition requires ≥140px plate width; high-accuracy enforcement requires ≥200px.

💾 Storage Capacity Calculator

Calculate total storage requirements for video retention and LPR event snapshots. Results include RAID overhead and 20% safety margin.

4
30 days
Main stream H.265 bitrate per camera
Main stream H.265 bitrate per camera
200/lane/day
Average plate crop + overview image size
RAID-0=1.0, RAID-1=2.0, RAID-5=1.33, RAID-6=1.5
Storage Requirements
—Video Storage
—Snapshot Storage
—Net Total
—Raw (with margin)
Raw capacity includes 20% safety margin. Purchase drives to meet or exceed this figure.
Video: Lanes × (LPR_Mbps + OV_Mbps) × 3600 × 24 × Days ÷ 8 ÷ 10¹² × RAID_Factor
Snapshots: Lanes × Events/Day × Snapshot_KB ÷ 1024 × Days
Raw Capacity: (Video_TB + Snapshot_TB) × 1.20

📡 Network Bandwidth Calculator

Calculate required network bandwidth for field switches and uplinks. Includes video streams, LPR event data, and management traffic.

4
Total for all lanes (images + metadata)
Bandwidth Requirements
—Field Switch Load
—Central Uplink
—Total Bandwidth
—Switch Capacity Req.
Field switch must support 130% of calculated field bandwidth. Use GbE uplinks for all field switches.
Field BW: Lanes × (LPR_Main + OV_Main)
Central BW: Lanes × (LPR_Sub + OV_Sub) + Events + Management
Switch Capacity: Field_BW × 1.30 (30% headroom for burst traffic)

⚡ PoE Power Budget Calculator

Calculate the total PoE power budget required for your field switch. Results include 20% safety margin and recommended switch PoE budget.

4
4
4
0
Typical PoE+ LPR camera: 15–30W
Typical PoE+ illuminator: 20–60W
PoE Power Budget
—Total Load (W)
—With 20% Margin (W)
—PoE Ports Needed
—Min. Switch Budget (W)
Select a PoE switch with a total budget ≥ the calculated minimum switch budget. Verify per-port limits match device requirements.
Total Load: Σ(Device_Count × Device_Power)
With Margin: Total_Load × 1.20
Switch Budget: CEILING(Margin ÷ 30) × 30 (rounded up to nearest 30W increment)

⏱ Shutter Speed Calculator

Calculate the maximum allowable shutter speed to limit motion blur to an acceptable level for your target vehicle speed and capture geometry.

80 km/h
1.0 px
Recommended: ≤1px for high accuracy; ≤2px for standard
Shutter Speed Results
—Max Shutter Time
—Recommended Setting
—Estimated Blur
Status: — — Recommended setting is 50% of maximum for safety margin.
Max Shutter (μs): Max_Blur_px ÷ (Speed_m/s × Pixels_per_meter) × 10⁶
Pixels/meter: √(Resolution_MP × 10⁶) ÷ FoV_width_m
FoV width: Sensor_Width_mm × Distance_m ÷ Focal_Length_mm
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