Flight Category Checker
Determine VFR, MVFR, IFR, or LIFR flight category from ceiling height and visibility. The most restrictive factor determines the overall category. A ceiling is the lowest broken or overcast cloud layer (not few or scattered).
Flight Category Thresholds
| Category | Ceiling (ft AGL) | Visibility (SM) |
|---|---|---|
| VFR | > 3,000 | > 5 |
| MVFR | 1,000 – 3,000 | 3 – 5 |
| IFR | 500 – 999 | 1 – < 3 |
| LIFR | < 500 | < 1 |
Ceiling vs. Cloud Layer
A ceiling is the lowest layer of clouds reported as broken (BKN) or overcast (OVC). Few (FEW) and scattered (SCT) cloud layers are not considered a ceiling. When determining flight category, only the ceiling matters for the cloud component — not individual scattered layers.
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Frequently Asked Questions
Flight category is based on the values you enter. Always use official weather sources (METARs, TAFs, 1800wxbrief.com) for actual conditions. Weather can change rapidly. This tool is not a substitute for a proper weather briefing. Read our full Safety Disclaimer.
Last reviewed: July 2026
Flight Categories in Depth
Flight categories — VFR, Marginal VFR, IFR, and Low IFR — are a shorthand that classifies current weather conditions by ceiling and visibility into bands that map directly to how demanding a flight will be. A single glance at a category tells a pilot whether conditions are comfortably visual, marginal, or firmly instrument, which is why they appear on aviation weather briefings and charts. This calculator assigns the category from the ceiling and visibility you enter.
The categories exist because raw numbers are easy to misjudge under pressure. Translating a 1,800-foot ceiling and 4-mile visibility into "Marginal VFR" instantly frames the risk in a way that supports a good decision, especially for VFR-only pilots for whom the boundary between categories can be the boundary between a legal, safe flight and one that is neither.
Step-by-Step: How the Calculation Works
The standard definitions are based on the more restrictive of ceiling and visibility. VFR is a ceiling greater than 3,000 feet and visibility greater than 5 statute miles. Marginal VFR is a ceiling of 1,000 to 3,000 feet inclusive and/or visibility of 3 to 5 miles. IFR is a ceiling of 500 to below 1,000 feet and/or visibility of 1 to less than 3 miles. Low IFR is a ceiling below 500 feet and/or visibility below 1 mile.
Because the category is set by whichever value is worse, a high ceiling with low visibility still yields the lower category, and vice versa. The calculator evaluates both inputs against these thresholds and reports the resulting category, giving the same standardized answer used across aviation weather products so your interpretation matches the official one.
More Worked Examples
Example 1 — Marginal VFR by ceiling
Ceiling 2,000 ft, visibility 8 statute miles. Visibility alone would be VFR, but the 2,000-ft ceiling falls in the 1,000–3,000 ft Marginal VFR band. Because the more restrictive value governs, the category is Marginal VFR — a signal to a VFR pilot that terrain and obstacle clearance deserve extra caution.
Example 2 — IFR by visibility
Ceiling 4,500 ft, visibility 2 statute miles in haze. The ceiling is comfortably VFR, but 2 miles visibility falls in the 1-to-less-than-3-mile IFR band, so the conditions are IFR. A VFR-only pilot would not legally or safely depart into these conditions despite the high ceiling.
Pilot Decision-Making Context
Categories translate weather into personal-minimums decisions. Many VFR pilots set a personal rule to fly only in solid VFR, treating Marginal VFR as a signal to delay, choose a different route, or stay on the ground. Making that decision against a clear category rather than a borderline raw number removes ambiguity from a moment when optimism can cloud judgment.
The category also frames the whole flight, not just the departure. Conditions forecast to drop from VFR to Marginal VFR or IFR during the flight warn of a deteriorating trend that could trap a VFR pilot, so a category is best read as part of a trajectory. Watching the forecast categories along the route and timeline supports the classic advice to leave yourself an out.
More Questions Answered
Which counts more, ceiling or visibility?
Whichever is more restrictive. The flight category is set by the worse of the two, so a good ceiling cannot offset poor visibility or vice versa.
Is Marginal VFR legal for a VFR pilot?
It can be legal if the specific airspace visibility and cloud-clearance minimums are met, but it is demanding, and many pilots adopt personal minimums that keep them out of Marginal VFR conditions.
What is a ceiling?
The ceiling is the height above the ground of the lowest broken or overcast cloud layer, or the vertical visibility into an obscuration. Scattered layers do not constitute a ceiling.
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