The ESS Toolbox
Engineering calculators, field reference and documentation links for people who design, install and maintain electronic security systems. Free, with no sign-up.
- Every formula is shown. If you cannot check the arithmetic, do not trust the number.
- Nothing leaves your device. The calculators run in your browser with no tracking.
- Every calculation is shareable. Copy the link and a colleague opens the same inputs.
Video surveillance tools
Camera placement, lens selection, storage, retention and network load for video surveillance systems.
- Pixel Density Will this camera actually do the job at that distance? Pixels per foot and per metre, classified against the standard detect / observe / recognise / identify tiers.
- Lens / Field of View Solve for focal length, angle of view, scene width, or distance given the other three. The diagram updates as you type.
- VMS Storage How much storage this camera set actually needs for the retention you promised, with headroom.
- RAID Capacity and Retention Usable capacity of a recorder or storage array by RAID level, how many drive failures it survives, and how many days of video it actually holds.
- Network Bandwidth Aggregate stream load for a camera set, split into recording and live view, with uplink sizing for the access and distribution layers.
Power and cabling tools
PoE budgets, lock power, voltage drop, battery standby and conduit fill for access control and low-voltage work.
- PoE Budget Total switch power required by a device list, with cable loss and headroom against the switch you actually specified.
- Lock Power Budget Power supply size for an access control door set: locks, readers and sensors, the worst-case simultaneous unlock, and the battery standby that follows.
- Voltage Drop What voltage actually arrives at the device on a 12 or 24 VDC run, checked against its minimum operating voltage.
- Battery Standby Amp-hour capacity required to hold a system up for the standby period, with derating for age and temperature.
- Conduit Fill Fill percentage for a conductor list against the NEC limits, with the smallest trade size that passes.
Field resources
Reference tables we keep on our own phones, and the places to find the manufacturer's current documentation.
Field reference
Wiegand and OSDP reader wiring, PoE power classes, wire resistance and voltage drop by gauge.
Technician library
Direct links to manufacturer documentation portals and the federal standards that govern security systems.
Design tools
Planning tools in development: camera coverage, door hardware schedules, panel capacity and cable schedules.