Online PA System Calculator: Power, Loudspeaker Count and Speech Intelligibility
The professional VPA online calculator sizes a complete voice evacuation and public address (PA) system: point-by-point sound pressure level and speech intelligibility, loudspeaker count and layout, amplifier power, cable cross-section and backup power capacity — all checked against the applicable codes, with a bill of materials and a layout drawing ready to export.
The tool runs right in your browser. For larger projects and floor-plan upload, it is more convenient to open it full screen on a desktop computer.
What the calculator computes
This is not a rough power estimate but a full electroacoustic calculation: the software builds a sound pressure field over an adaptive grid of thousands of points and checks the result against the regulatory requirements for voice evacuation and emergency announcements.
SPL at every point, direct and reverberant field, Speech Transmission Index (STI) per IEC 60268-16, and signal level above ambient noise.
Automatic verification against SP 3.13130.2026 (Russian fire-safety code, indoor spaces) and GOST R 42.3.01-2021 (Russian standard for outdoor civil alert systems), plus EN 54-32; percentage of floor area meeting the requirement.
Automatic selection of the number of loudspeakers and the layout pattern (line, grid, perimeter, staggered), installation spacing, with manual fine-tuning on the map.
Amplifier power with a 25 % margin over the total loudspeaker load, number of zones, and 100 V line configuration.
Fire-resistant line cable cross-section calculated from allowable losses, accounting for run length and load (per GOST 31565, the Russian fire-resistant cable standard).
Power consumption in each operating mode and sizing of the backup power source capacity (UPS / batteries).
How it works — 4 steps
- Define the room or outdoor area.
Enter the dimensions, ceiling height and facility type from a catalog of 50+ occupancies (the regulatory ambient noise level is filled in automatically), or choose an outdoor site.
- Upload a floor plan.
PDF, JPEG or PNG with scale calibration and outline tracing — the sound pressure heat map is overlaid on your actual plan, to scale.
- Get the calculation and layout.
The software selects the loudspeaker type and count, the amplifier and the cable, and renders SPL, SNR and intelligibility heat maps with a code compliance check.
- Export the bill of materials and quote.
The commercial quote and the full engineering calculation export to Word, Excel and PDF, and the layout drawing to DXF (AutoCAD). One click sends everything by email.
Export options
The finished calculation turns into documents you can attach to a project, a tender or an invoice request:
Who it is for
The tool is built for the professionals who specify and purchase PA and alert equipment: design engineers — to quickly validate a solution and export a drawing; procurement staff and safety officers — to obtain an accurate bill of materials and a commercial quote for their site without manual recalculation. The calculation is free and requires no sign-up.
Frequently asked questions
Run the calculation and request an invoice for the selected equipment. Warehouse in Moscow, delivery across Russia, invoice-based ordering for businesses.
VPA is a supplier of voice evacuation and public address equipment. Calculation results are preliminary; design and installation are performed by a licensed organization.