Flight categories: VFR, MVFR, IFR, LIFR

Weather charts and apps often colour airports as VFR, MVFR, IFR or LIFR. This flight category is a quick summary of how good the weather is, computed from two numbers in the METAR: the visibility and the ceiling.

The thresholds

Category	Ceiling	Visibility
VFR	above 3,000 ft	more than 5 SM (8 km)
MVFR	1,000 to 3,000 ft	3 to 5 SM (4.8 to 8 km)
IFR	500 to below 1,000 ft	1 to below 3 SM (1.6 to below 4.8 km)
LIFR	below 500 ft	below 1 SM (1.6 km)

VFR stands for visual flight rules, MVFR for marginal VFR, IFR for instrument flight rules and LIFR for low IFR. The worse of the two numbers decides the category: a ceiling of 800 ft with 10 km visibility is still IFR.

What counts as the ceiling?

The ceiling is the height of the lowest broken (BKN) or overcast (OVC) layer, or the vertical visibility (VV) when the sky is obscured. FEW and SCT layers do not count. Heights are above the airport elevation.

Worked examples

9999 SCT030: visibility 10 km, no ceiling (scattered only). VFR.
6000 -RA BKN012 OVC025: visibility 6 km is about 3.7 SM and the ceiling is 1,200 ft. Both are in the marginal range. MVFR.
3000 +TSRA BKN008CB: visibility 3,000 m is about 1.9 SM and the ceiling is 800 ft. IFR. (try this one in the decoder)
CAVOK: visibility 10 km or more and no significant cloud. VFR.

Important caveats

These categories are a US FAA and National Weather Service convention. They are a summary, not legal minima.
Actual VFR minima depend on the country, the airspace class, the altitude and whether it is day or night. In Europe the rules of the air (SERA) and national rules apply.
A category describes the airport at the time of the report. Check the TAF for the trend, and the full METAR for gusts and weather.

See real reports: EGLL · KJFK · EDDF · EPWR · all airports.

Educational material. It does not replace flight training or an official weather briefing.