Density Altitude from METAR (Humidity-Corrected)
Compute humidity-corrected density altitude straight from METAR numbers — QNH, temperature and dew point — using the virtual-temperature method.
Water vapor is lighter than dry air, so muggy air is thinner than the plain temperature suggests. The virtual-temperature method captures what the classic E6B formula misses.
Formula
⚠️ For flight planning and education only — always verify against your aircraft's POH/AFM, official weather sources and certified instruments. Not for primary navigation or airworthiness decisions.
Compute humidity-corrected density altitude straight from METAR numbers — QNH, temperature and dew point — using the virtual-temperature method.
About Density Altitude from METAR (Humidity-Corrected)
Most density-altitude tools ignore humidity, yet on a humid summer evening the air can be a few hundred feet 'higher' than the dry formula claims. This calculator reads the same numbers you already have in a METAR — QNH, temperature and dew point — and computes a humidity-corrected density altitude using the meteorologically correct virtual-temperature method, alongside the classic dry value so you can see the difference.
How to use Density Altitude from METAR (Humidity-Corrected)
- 1Enter — sensible defaults are pre-filled so you see a worked result immediately.
- 2Read the live results: .
- 3Check the "With your numbers" line to see the formula e = 6.112·e^(17.67·Td/(Td+243.5)); Tv = T/(1 − (e/p)(1 − 0.622)); DA = PA + 118.8 × (Tv − ISA) substituted step by step.
- 4Adjust inputs (or flip the unit toggle) until the scenario matches yours, then copy or share the result.
Why use Density Altitude from METAR (Humidity-Corrected)?
- ✓Instant, free and private — every calculation runs in your browser, nothing is uploaded
- ✓Built on the published formula e = 6.112·e^(17.67·Td/(Td+243.5)); Tv = T/(1 − (e/p)(1 − 0.622)); DA = PA + 118.8 × (Tv − ISA) with sources cited on the page
- ✓Water vapor is lighter than dry air, so muggy air is thinner than the plain temperature suggests. The virtual-temperature method captures what the classic E6B formula misses.
- ✓Switch units, tweak any input and watch every result update live
Frequently asked questions
How does dew point raise density altitude?+
Dew point sets the water-vapor content of air. A water molecule (18 g/mol) weighs less than the average air molecule (29 g/mol), so moist air at the same pressure and temperature is less dense. The virtual-temperature correction expresses that density loss as extra warmth, which the standard DA formula then turns into extra feet.
How big is the humidity effect in practice?+
Typically 100–600 ft. It is largest when both temperature and dew point are high — a 33 °C day with a 25 °C dew point can add over 500 ft compared with the dry calculation. In cold or dry air the correction shrinks to almost nothing, which is why winter pilots rarely notice it.
Which numbers do I take from the METAR?+
Three of them: the altimeter setting (the A-group, e.g. A3005 → 30.05 inHg), the temperature and the dew point from the temperature group (e.g. 33/08 → 33 °C and 8 °C). Field elevation comes from the chart supplement or your EFB airport page.
Is the dry-formula value wrong, then?+
It is a deliberate simplification that errs slightly optimistic. The FAA's standard formula assumes dry air because the error is small and on most days conservative planning margins absorb it. On hot, humid, high-elevation days the gap widens — exactly the days when performance is already marginal, which is when this tool earns its keep.
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