Field calculators for security & electrical technicians
No sign-up, no clutter — just the numbers you need on site: how much storage your NVR needs, how much bandwidth your cameras will pull, and how big a battery bank you need to back it all up.
CCTV & Security Systems
NVR Storage Calculator
Work out exactly how many terabytes you need for any number of cameras, resolution, and retention period.
CCTV-02IP Camera Bandwidth Calculator
Calculate total network bandwidth for a camera install so your switch and NVR ports aren't overloaded.
CCTV-03CCTV Storage Calculator
For analog HD-CCTV (DVR) or IP (NVR) systems — pick your hardware type and get the exact drive size.
CCTV-04Camera Field of View Calculator
Estimate lens focal length and coverage distance for identification vs. detection.
Electrical & Battery
Amp Hour Calculator
Convert watts, amps, and runtime into the battery amp-hour capacity you actually need.
ELEC-02Battery Backup Calculator
Size a backup battery for alarm panels, NVRs, or PoE switches based on standby load and runtime.
ELEC-03Battery Amp Hour Calculator
Already have a battery? Enter its Ah rating and load to find out how many hours it'll actually run.
Field Guides
NVR Storage Calculation: 12 Mistakes That Leave You Short on Space
The formula is simple — 12 real-world factors are why the calculated number is often wrong.
IP Camera Bandwidth: Why the Switch (and PoE Budget) Fail First
Switch uplink overload and PoE power budget — the check most junior installers skip.
Analog vs. IP CCTV in 2026: Which Should You Actually Install
An honest, experience-based breakdown — not just "newer is always better."
How to Choose the Right Battery Size for a Security Panel
Exact Ah calculation, series vs. parallel wiring, and why lithium usually wins now.
Choosing the Right CCTV Lens: Coverage vs. Identification Distance
Why a wider lens usually means less detail — and how to actually match focal length to the job.
Why GaugeCalc?
Most calculators online are built by marketers, not by people who actually climb ladders and pull cable. GaugeCalc is built by a working security systems technician — every formula here reflects what actually happens on a real job, not just a textbook spec sheet.
Every tool on this site is free, requires no sign-up, and runs entirely in your browser — your project details never leave your device.