Free browser-based tools for ISP and telecom NOC engineers. No login, no installation — all calculations run locally in your browser.
These tools cover four different jobs in an OSP/NOC workflow, and it's easy to grab the wrong one when several sound similar. Here's the fast version:
Designing or validating a new fiber link? Start with the Fiber Loss Calculator — it's the only tool here that gives you a full power budget (Tx power minus Rx sensitivity minus every loss source) and tells you whether a link will actually work before you build it. If the link is a PON/FTTH split rather than a point-to-point run, use the PON/FTTH Power Budget Calculator instead — it accounts for splitter loss the plain fiber calculator doesn't model.
Troubleshooting a fault on plant that already exists? The three OTDR tools split cleanly by what stage of the job you're in. Before you even test, the OTDR Dead Zone Calculator tells you how close to your OTDR unit an event can hide, and what launch cable length fixes it. After you've pulled a trace, the OTDR Viewer opens the raw .sor file so you can see the trace and measure between events without installing anything. If the raw OTDR distance doesn't match where the fault is on the ground, the Cable Slack & OTDR Distance Correction tool is the one that reconciles the two — slack coiled in splice enclosures makes OTDR distance read longer than the straight-line route distance, and this tool backs that out.
Managing an active outage? These three run in sequence during a real incident: the SLA Breach Calculator tells you how much runway is left before you owe a credit, the Outage Impact Calculator quantifies what that outage is actually costing across your subscriber base, and the Outage Notification Generator drafts the customer-facing message so nobody's writing one from scratch at 2am.
Just need a reference lookup? The Fiber Color Code Reference is a pure TIA-598-C lookup — no calculation, just "what color is fiber 47 in a 144-count cable."
Working on copper instead of fiber? The Ethernet Cable Loss Calculator checks a Cat5e/Cat6/Cat6A run against TIA-568 channel insertion loss limits and tells you the fastest Ethernet standard that run actually supports at its length — useful anywhere the job is twisted-pair, not optical.
Installing a coax drop? The Coax Splitter Loss Calculator covers the tap-to-device side of the job — RG-6/RG-11 drop cable plus every splitter in the path, checked against the DOCSIS signal level range so you know before you leave whether a device needs a home distribution amplifier.
Look up fiber strand colors by number or find fiber numbers by color. Supports 12 to 288-fiber cables using TIA-598-C color coding standard.
Use Tool →Calculate total optical loss, power budget, link margin, and maximum fiber span for SMF and MMF links with connectors, splices, and MUX/DEMUX devices.
Use Tool →Calculate OTDR event and attenuation dead zones from pulse width. Get recommended launch cable length and a full dead zone reference table for all pulse widths.
Use Tool →Open a .sor OTDR trace file right in your browser. See the full trace graph and auto-detected events, then drop markers to read the footage between any two points.
Use Tool →Convert raw OTDR distance to actual ground distance by accounting for splice enclosure slack coils and route deviation. Improve fault location accuracy.
Use Tool →Full optical power budget for GPON, XGS-PON, and 10G-EPON networks. Supports single and two-stage splitting, connectors, splices, and safety margin.
Use Tool →Check TIA-568 channel insertion loss for a copper twisted-pair run, see pass/marginal/fail margin, and find the fastest Ethernet speed your cable category and length actually support.
Use Tool →From the tap to the customer's devices: check drop cable and splitter loss against the DOCSIS signal level range, and know when it's time for a home distribution amplifier.
Use Tool →Live countdown to SLA breach with real-time penalty exposure calculation. Supports 99.9%, 99.99%, 99.999%, and 4-hour MTTR SLA types.
Use Tool →Calculate total revenue exposure from a fiber outage across residential, SMB, and enterprise subscribers. Live counter grows every second the outage is open.
Use Tool →Generate professional outage notification templates for residential, SMB, and enterprise customers. Includes customer email, 160-char SMS, and formal SLA notification.
Use Tool →Upload an OTDR trace, enter cable route addresses — deterministic, slack-aware math (not AI guesswork) locates the fiber break to within about 500 feet on a satellite map with street view of the fault location. Built for ISP and carrier operations teams. Now also captures real as-built data as you build: place every splice enclosure, splitter, and tap at its real GPS coordinate, branch for true FTTx topology, and export one GIS-ready package for the provider instead of separate paperwork.
Start free trial · opticalpathengineering.com →Auto-calculates power draw, HVAC load, generator runtime, and DC-plant capacity for a hub, headend, data center, or IT server room from what's actually installed — replacing manual spreadsheet audits with a live utilization dashboard. Part of the Facility Database System.
Learn more · opticalpathengineering.com →Full hub, rack, and device documentation with MUX/preterm chassis support and circuit tracing from device to customer — keeps facility records accurate without a manual spreadsheet audit. Part of the Facility Database System.
Learn more · opticalpathengineering.com →Do these tools require a login or send my data anywhere?
No. Every calculation on this site runs entirely in your browser using JavaScript — nothing you type is uploaded, stored, or sent to a server. That's true even for the OTDR Viewer, which parses .sor files locally rather than uploading them.
Are these tools accurate enough for production engineering decisions?
They're built to match the same formulas and standards (TIA-598-C, ITU-T dead zone definitions, DOCSIS/PON power budget math) that professional OSP engineering software uses, and several are direct spin-offs of a commercial fault-location product. That said, always sanity-check a critical design against your own test equipment or a second source — a free web calculator is a design aid, not a substitute for field verification.
Why are there both a Fiber Loss Calculator and a PON/FTTH Power Budget Calculator?
They solve different topologies. The Fiber Loss Calculator assumes a single point-to-point fiber with discrete connectors/splices/MUX devices. PON/FTTH networks split one fiber into many via passive optical splitters, which have their own loss characteristics the point-to-point tool doesn't model — hence a dedicated calculator.
New to fiber or NOC engineering?
Start with the blog for walkthroughs like how to read an OTDR trace before jumping into the calculators — the tools assume you already know what an event, a splice, or an MTTR clock is.