Fiber Bandwidth-Distance Calculator
Determine maximum fiber optic cable distance for a target data rate by fiber type (OS2, OM1-OM5). Based on IEEE 802.3 standards.
About this calculator
Fiber optic links have a hard reach limit that depends on both the fiber type and the data rate you're pushing through it, and the two failure modes behind that limit are different for single-mode and multi-mode fiber. Single-mode (OS2) distances in this calculator are attenuation-limited -- the signal simply fades with distance, so reach is set by wavelength and how much optical power budget the transceiver has, which is why OS2 can reach tens of kilometers regardless of data rate up to a point. Multi-mode fiber (OM1 through OM5) is instead bandwidth-distance-product limited: each grade has a fixed modal bandwidth rating in MHz*km, and higher data rates eat into that budget faster, so reach drops sharply as the target rate climbs -- OM3's 2,000 MHz*km rating supports 1 Gbps to 1,000 m but only 300 m at 10 Gbps (OM4/OM5's higher 4,700 MHz*km rating is what reaches 400 m at 10 Gbps).
Bandwidth Limited (1=Yes) flags which regime is active for your combination: 0 means the single-mode attenuation path, 1 means the multi-mode modal-bandwidth path. Raising the data rate never increases the achievable distance for a fixed fiber type and wavelength -- the maximum reach only ever holds flat or drops as you ask for more bandwidth, since IEEE 802.3 standards trade reach for speed rather than offering both simultaneously. These are standard-based planning distances, not link-budget calculations for a specific transceiver and connector-loss combination.
Inputs
Results
Maximum Distance
10,000 m
≈ 30 Eiffel Towers
Maximum Distance
10 km
≈ 30 Eiffel Towers
Figures current as of 2022. Source: IEEE Std 802.3-2022 (consolidating amendments including 802.3z, 802.3ae, 802.3ba, 802.3bm, and 802.3cd), IEEE Standard for Ethernet, physical medium dependent (PMD) sublayer clauses specifying maximum reach over OS2 single-mode and OM1-OM5 multi-mode fiber at each standardized Ethernet rate
How to Use This Calculator
- Select Data Rate (Mbps) and Fiber Type (OS2 Single-Mode, OM1, OM2, OM3, OM4, or OM5) for your application.
- Choose Wavelength (850 nm, 1310 nm, or 1550 nm) — multimode uses 850/1310 nm, single-mode uses 1310/1550 nm.
- Review Maximum Distance (m and km) — this is the link length limit for that fiber type and data rate.
- If the link is bandwidth-limited rather than attenuation-limited, Bandwidth Limited will show 1.
- Compare your planned cable run against the Maximum Distance — if too long, upgrade to single-mode or add a repeater.
What each input means
- Data Rate
- Target data rate (1000=1G, 10000=10G, 25000=25G, 100000=100G)
- Fiber Type
- OS2 is single-mode; OM1-OM5 are multi-mode grades with increasing modal bandwidth.
- Wavelength
- 850nm is used on multi-mode fiber; 1550nm is single-mode only. 1310nm works on both, which is why it's the default alongside OS2 single-mode.
How this is calculated
Formula
Based on IEEE 802.3 standard distances per fiber type and data rateWorked example, using the default values
- Identify Input ParametersData Rate = 10000, Fiber Type = 1, Wavelength = 2 = 3 input(s) provided
- Calculate Maximum DistanceMaximum Distance10000 = 10000
- Calculate Maximum DistanceMaximum Distance10 = 10
- Calculate Data Rate10 = 10
- Calculate Bandwidth Limited0 = 0
Figures and sources
- IEEE 802.3 — Ethernet standard, per-PMD maximum link distances by fiber type and data rate (2022) — IEEE Std 802.3-2022 (consolidating amendments including 802.3z, 802.3ae, 802.3ba, 802.3bm, and 802.3cd), IEEE Standard for Ethernet, physical medium dependent (PMD) sublayer clauses specifying maximum reach over OS2 single-mode and OM1-OM5 multi-mode fiber at each standardized Ethernet rate
Engine last updated . Checked against 6 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why does OS2 single-mode fiber reach so much farther than OM3 or OM4 at the same data rate?
OS2 single-mode fiber's reach is limited by signal attenuation, not modal bandwidth, so it can carry a 10 Gbps signal 10 km at 1310nm -- versus OM3's roughly 300 m (or OM4/OM5's roughly 400 m) at the same data rate -- because single-mode fiber doesn't suffer the modal dispersion that caps multi-mode reach. The tradeoff is cost: single-mode transceivers and connectors are generally more expensive than multi-mode equivalents for short campus or data-center runs.
Can raising the target data rate ever increase the maximum achievable distance?
No -- for a fixed fiber type and wavelength, Maximum Distance only ever holds steady or decreases as the target Data Rate rises, never increases. This reflects how IEEE 802.3 Ethernet standards are actually specified: each speed grade trades some reach for the extra bandwidth, so a 100G link over a given fiber type never reaches farther than a 1G link over that same fiber.
What does it mean when Bandwidth Limited shows 1 instead of 0?
A value of 1 means the link's maximum distance is set by the fiber's modal bandwidth-distance product (the multi-mode OM1-OM5 regime), while 0 means it's set by signal attenuation (the single-mode OS2 regime). This distinction matters for troubleshooting: a bandwidth-limited link can sometimes be extended with a higher-bandwidth fiber grade, while an attenuation-limited link needs a stronger transceiver or fewer connector losses instead.
Does the wavelength choice matter for both single-mode and multi-mode fiber the same way?
Not quite -- for single-mode (OS2), moving from 1310nm to 1550nm roughly doubles or quadruples the attenuation-limited reach at moderate data rates, since 1550nm light experiences lower fiber loss. For multi-mode fiber, 850nm (using inexpensive VCSEL transceivers) is the standard wavelength for most modern OM3/OM4/OM5 deployments, and this calculator's modal-bandwidth table is built around that pairing.
Related Calculators
The questions that sit next to this one — chosen by subject, including calculators filed under a different category.
Fiber Optic Loss Budget Calculator
Calculate total fiber link loss from cable length, connectors, splices, and splitter losses. Includes safety margin for reliable link design.
Fiber OpticsOptical Power Budget Calculator
Calculate optical link power budget from transmitter power, receiver sensitivity, link loss, and safety margin. Includes overload check.
Fiber OpticsFiber Count Calculator
Determine required fiber count for current and future capacity, including growth projection and standard cable size recommendation.
More in Technology & Computing.