Runway Designation Calculator — Tool Guide

Coming Soon AC 150/5300-13B CHG 1 · ALL GUIDES

The Runway Designation Calculator turns a runway's heading into its designation number — the 01–36 painted on the threshold — and back again. Enter a magnetic heading and it rounds to the nearest 10°, divides by 10, and returns the designator with its reciprocal end; enter a true heading with a known magnetic variation and it converts first. It also assigns the L/C/R suffixes for parallel runways and reverses the math to show the heading range a given runway number serves, per AC 150/5300-13B.

It replaces the usual workflow of recalling the rounding rule, doing the variation arithmetic by hand, and second-guessing which end gets the L and which gets the R — every result carries its citation and the exact computation behind it.

Open the Runway Designation tool →

Who It's For & When to Use It

Airport planners numbering a new or realigned runway, documenting an existing one in an ALP narrative or design report, or checking whether a designation is due to change as magnetic variation drifts. Use it when you have a survey or charted heading and need the painted designator, when a runway is being added or extended and you need to confirm the L/C/R lettering across a parallel set, or when you need the magnetic heading range a published runway number covers for a narrative or a crosswind analysis.

How to Use It

Supply the magnetic variation (optional). Enter an airport identifier — FAA LID or ICAO; a 3-letter code is read as US ICAO (DEN → KDEN) — to look up the published magnetic variation, or type the variation by hand: negative for West, positive for East. This unlocks true-heading conversion; without it the tool works directly in magnetic heading.
Choose magnetic or true heading mode. The segmented control selects whether you enter a magnetic heading directly or a true heading that the tool converts to magnetic using the variation above. True-heading mode is enabled only once a variation is known — until then a hint explains the precondition.
Enter the heading. Type the runway's heading in degrees (0–360). In true mode the computed magnetic heading is shown before the designation is derived, so you can see the variation applied.
Read the designation and reciprocal. The tool rounds the magnetic heading to the nearest 10° and divides by 10 to give the designation number (01–36), with the reciprocal end shown alongside. A breakdown line states the rounding math and the AC 150/5300-13B citation.
Assign L/C/R for parallel runways. Expand the parallel-runways panel and pick two or three parallels; the tool lays out the L/C/R suffix pairs — left, center, right — from the pilot's perspective on final approach, pairing each suffix with its reciprocal (per FAA Order 7400.2).
Reverse-look up a heading range. In the second section, enter a runway number (1–36) to see the magnetic heading range it serves, its center heading, and the reciprocal — with true equivalents shown when a variation is set.
Copy or share the result. Each section's copy button puts the designation (or heading range) and its source citation on the clipboard. The looked-up airport is written to the URL (?id=) so the address bar is a shareable link that restores it on return.

Key Features

Magnetic-or-true heading input. A discoverable segmented control switches between entering a magnetic heading directly and entering a true heading that is converted with the airport's variation — with the intermediate magnetic value shown so the conversion is auditable.
Variation lookup with citation. Look up an airport to pull its published magnetic variation and vintage (e.g. FAA NASR cycle), or enter the variation manually; the result line names the source so the figure is trail-backed.
Reciprocal-end numbering. Both runway ends are derived and shown together, so the full runway designation (e.g. 17 ↔ 35) is one read.
Parallel L/C/R assignment. Two- and three-runway sets are laid out with the correct suffix pairing from the pilot's approach view, with the FAA Order 7400.2 perspective note built in.
Reverse heading-range lookup. Enter a runway number to recover the magnetic heading range, center heading, and reciprocal — with true equivalents when a variation is set.
Source-cited fallback handling. Airport lookups that fall back to community OurAirports data surface a blocking continue/stop banner, so a non-authoritative variation is never used silently.
Citation trail and shareable URL. Every copied result carries the AC 150/5300-13B designator rule and its variation source, and the looked-up airport is mirrored into the query string for deep-links.

FAA References

AC 150/5300-13B Chg 1, Airport Design — governing standard; the runway designator is the magnetic heading divided by 10, rounded to the nearest whole number (01 through 36).
FAA Order 7400.2, Procedures for Handling Airspace Matters — basis for the parallel-runway L (left), C (center), and R (right) suffix convention, assigned from the pilot's perspective on final approach.
Magnetic variation used for true-to-magnetic conversion is sourced from the airport record (FAA NASR, with cycle date) or entered manually; community OurAirports data is flagged as non-authoritative when it is the fallback source.

Limitations & Disclaimers

AvPlot is technical planning production support — accurate enough for design reports, planning studies, and ALP narratives. It is not a replacement for stamped engineering or construction documents. As the tool itself states: runway designations are based on magnetic north, and as magnetic declination changes over time the FAA may update them. Always verify against the current FAA Chart Supplement and active NOTAMs before use in official documents.

The designator is the published magnetic value; a heading right on a 5° boundary, or a runway recently re-designated for variation drift, should be confirmed against the current Chart Supplement.
True-heading conversion is only as good as the variation supplied — an out-of-date or community-sourced variation will skew the magnetic result.
L/C/R assignment assumes a standard parallel layout; it does not resolve non-standard lettering or local exceptions.

Related Tools

Runway Linework Generator — draws the runway and its safety surfaces as CAD-ready linework once the designation is set (guide).
RSA / ROFA / ROFZ Reference — Runway Safety Area and Object Free Area dimensions for the runway you've designated (guide).
Declared Distance Calculator — full TORA/TODA/ASDA/LDA analysis per runway end (guide).
ARP Lookup — official FAA airport reference data, including the published magnetic variation (guide).

Tips & Best Practices

Look up the airport first when you have a true heading from a survey — it both fills the variation and lets you cite the NASR cycle behind the conversion, rather than carrying a remembered figure.
Watch headings near a 5° rounding boundary: a small survey or variation difference can flip the designator to the adjacent number, so confirm the published value against the Chart Supplement.
For new parallels, set the count before reading the suffixes — the L/C/R pairing is from the pilot's approach view, not a north-up map, which is the most common error to avoid.
Use the reverse heading-range lookup when writing crosswind or wind-coverage sections; it gives the exact magnetic band a published runway number serves.
Copy the result into your notes — the clipboard text carries the designator rule and the variation source, documenting the basis for the number you cited.