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이슬점 계산기

기온과 상대 습도로부터 마그누스 수식을 사용하여 이슬점 온도를 계산하세요. 습도 수준, 쾌적성 분류, 절대 습도를 무료 온라인 계산기로 확인하세요.

빠른 계산

이슬점

17°C

응결이 시작되는 온도

상대 습도 (%)

60%

절대 습도

0.1 g/m³

쾌적 수준

약간 습함

공기가 약간 습하다고 느껴집니다. 공기 중 습기를 알아차리기 시작하는 사람들도 있습니다.

이슬점 공식 (마그누스 공식)

Td = (b × α(T, RH)) / (a - α(T, RH))

여기서:

  • α(T, RH) = (a × T) / (b + T) + ln(RH/100)
  • a = 17.27
  • b = 237.7°C
  • T = 기온 (°C)
  • RH = 상대 습도 (%)

마그누스 공식은 -40°C~50°C 온도 범위에서 잘 작동하는 근사식입니다. 기상학 및 HVAC 응용 분야에서 널리 사용됩니다.

습도에 대해 이해하기

상대 습도 (%)

해당 온도에서 공기가 유지할 수 있는 최대량과 현재 수분량을 비교합니다. 백분율이 높을수록 용량 대비 더 많은 수분이 있음을 의미합니다.

절대 습도

주어진 부피의 공기에 있는 수증기의 실제 질량으로, 입방미터당 그램(g/m³)으로 측정됩니다. 상대 습도와 달리 일정 부피에서는 온도에 따라 변하지 않습니다.

이슬점

공기가 포화 수증기에 도달하여 수증기가 응결되기 시작하는 온도입니다. 수분 함량의 직접적인 지표이며 쾌적성을 평가할 때 상대 습도보다 신뢰성이 높습니다.

이슬점이 중요한 이유

이슬점은 공기가 얼마나 무덥게 느껴지는지를 나타냅니다. 이슬점이 10°C(50°F) 미만이면 쾌적하지만, 20°C(68°F) 이상이면 불쾌하게 느껴집니다. 이슬점은 상대 습도와 달리 하루 종일 크게 변동하지 않습니다.

이슬점 차트 (°C)

온도 (°C)20%30%40%50%60%70%80%90%
0°C-20-15-12-9-7-5-3-1
5°C-16-11-7-5-2023
10°C-12-7-303578
15°C-8-2257101213
20°C-426912141618
25°C06101417192123
30°C511151821242628
35°C915192326293133

색상 코딩: 파랑=매우 건조, 초록=쾌적, 노랑=약간 습함, 빨강=습함/무더위. 이슬점 값은 °C로 표시.

How to Use

  1. 1

    Select your unit system — Imperial (°F) or Metric (°C)

  2. 2

    Choose your input mode: enter either relative humidity (%) or dew point temperature

  3. 3

    Enter the current air temperature — the calculator supports a wide range from -40°C to 50°C

  4. 4

    If using relative humidity mode, enter the humidity percentage (0-100%) — this is the most common way to calculate dew point from weather data

  5. 5

    If using dew point mode, enter the dew point temperature directly — useful when weather reports show dew point instead of relative humidity

  6. 6

    View your dew point temperature, relative humidity, and absolute humidity in g/m³

  7. 7

    Check the comfort level indicator to understand how the air feels — from Very Dry to Very Humid

  8. 8

    Use the quick calculate buttons for common indoor and outdoor humidity scenarios to quickly compare conditions

  9. 9

    Review the dew point chart below to see how dew point changes across different temperature and humidity combinations for planning outdoor activities or HVAC settings

예시

좋은 예시

Comfortable indoor conditions

22°C air temperature with 50% relative humidity → dew point of 11°C — Comfortable: ideal for most indoor activities and sleeping

Muggy summer day

32°C air temperature with 85% relative humidity → dew point of 29°C — Very Humid: oppressive conditions, limit outdoor exertion

Dry winter air

18°C indoor temperature with 25% relative humidity → dew point of -2°C — Very Dry: consider using a humidifier to prevent skin irritation and respiratory discomfort

Weather report interpretation

Air temperature 28°C, dew point 20°C → relative humidity ≈ 62%, absolute humidity ≈ 17.3 g/m³ — Slightly Humid: noticeable but tolerable for outdoor exercise

Comparing indoor vs outdoor comfort

Indoor: 23°C, 45% RH → dew point 10°C (Comfortable). Outdoor: 30°C, 75% RH → dew point 25°C (Humid). The difference explains why stepping outside feels oppressive

HVAC system optimization

Target dew point of 10-15°C for ideal indoor comfort. If current reading is 22°C dew point, the air conditioning should reduce humidity to bring it within the comfort zone

나쁜 예시

Confusing dew point with relative humidity

A dew point of 20°C always means the same moisture content regardless of air temperature, but relative humidity at 20°C dew point varies from 47% at 30°C to 100% at 20°C

Ignoring dew point for outdoor exercise

A dew point above 20°C significantly impairs the body's cooling ability — exercise performance drops and heat illness risk increases even if the air temperature seems moderate

Assuming low relative humidity means comfortable conditions

At 35°C with 30% RH, the relative humidity seems low but the dew point is 15°C — the heat itself is the main concern, not moisture

흔한 실수

  • Confusing dew point with relative humidity — dew point is an absolute measure of moisture that does not change with temperature, while relative humidity varies throughout the day as temperature changes
  • Assuming a low relative humidity means the air is dry — in hot weather, even 40% RH can have a high dew point indicating substantial moisture in the air
  • Not realizing that dew point is the best indicator of comfort — meteorologists prefer dew point over relative humidity because it directly measures how muggy the air feels
  • Forgetting that dew point can never exceed the air temperature — when they are equal, relative humidity is 100% and condensation or fog forms
  • Confusing absolute humidity with relative humidity — absolute humidity measures the actual mass of water vapor per unit volume (g/m³), while relative humidity is a percentage of saturation
  • Not accounting for indoor humidity in winter — cold outdoor air holds less moisture, so when heated indoors without a humidifier, the relative humidity drops and dew point falls, causing dry skin and respiratory issues
  • Assuming dew point calculations are the same across all formulas — the Magnus formula used here is accurate for -40°C to 50°C, but different formulas may give slightly different results at extreme temperatures
  • Using dew point and wet bulb temperature interchangeably — they measure different things; dew point indicates moisture content, while wet bulb temperature accounts for evaporative cooling potential

자주 묻는 질문

Q

What is the dew point formula?

The Magnus formula for dew point is: Td=b⋅α(T,RH)a−α(T,RH)T_d = \frac{b \cdot \alpha(T, RH)}{a - \alpha(T, RH)}, where α(T,RH)=a⋅Tb+T+ln⁡(RH100)\alpha(T, RH) = \frac{a \cdot T}{b + T} + \ln\left(\frac{RH}{100}\right), with constants a=17.27a = 17.27 and b=237.7°Cb = 237.7\text{°C}. This formula is accurate for temperatures between -40°C and 50°C and is widely used in meteorology and HVAC applications.

Q

What is a comfortable dew point for indoor air?

A dew point between 10°C and 15°C (50°F to 59°F) is considered ideal for indoor comfort. Below 5°C (41°F), the air feels very dry and can cause skin irritation and respiratory discomfort. Above 20°C (68°F), the air feels muggy and uncomfortable. The US Occupational Safety and Health Administration recommends maintaining indoor relative humidity between 20-60%, which typically corresponds to dew points in the 5-16°C range.

Q

What is the difference between dew point and relative humidity?

Dew point is the temperature at which air becomes saturated with water vapor — it directly measures the amount of moisture in the air. Relative humidity is the percentage of moisture in the air compared to the maximum it can hold at the current temperature. Unlike relative humidity, dew point does not change throughout the day as temperature changes, making it a more reliable indicator of how muggy the air feels.

Q

At what dew point does it feel muggy?

Most people start to notice humidity when the dew point reaches 16°C (60°F). At 20°C (68°F), it feels oppressive and uncomfortable. Above 24°C (75°F), the air feels tropical and outdoor activities become difficult. For reference, a dew point below 10°C (50°F) feels comfortable and refreshing, while below 0°C (32°F) feels very dry.

Q

How to calculate dew point from temperature and humidity step by step?

Step 1: Measure the air temperature in °C. Step 2: Measure the relative humidity as a percentage. Step 3: Calculate α = (17.27 × T) / (237.7 + T) + ln(RH/100). Step 4: Calculate dew point = (237.7 × α) / (17.27 - α). For example, at 25°C and 60% RH: α = (17.27 × 25)/(237.7 + 25) + ln(0.6) = 1.644 + (-0.511) = 1.133. Dew point = (237.7 × 1.133)/(17.27 - 1.133) = 269.3/16.137 = 16.7°C.

Q

Dew point vs humidity — which is better for measuring comfort?

Dew point is generally a better measure of comfort than relative humidity. This is because dew point directly measures moisture content and stays relatively constant throughout the day, while relative humidity fluctuates with temperature. A dew point of 20°C feels equally muggy whether the air temperature is 25°C or 35°C, but the relative humidity would be very different in those two scenarios.

Q

What is absolute humidity and how does it relate to dew point?

Absolute humidity measures the actual mass of water vapor in a given volume of air, expressed in grams per cubic meter (g/m³). It is calculated using the formula: AH=6.112×e17.67TT+243.5×RH×2.1674273.15+T\text{AH} = \frac{6.112 \times e^{\frac{17.67T}{T+243.5}} \times RH \times 2.1674}{273.15 + T}. Unlike relative humidity, absolute humidity does not change with temperature at a fixed volume. It is directly related to dew point — a higher dew point means higher absolute humidity.

Q

How does dew point affect weather and precipitation?

When the air temperature drops to the dew point, the air becomes saturated and water vapor begins to condense, forming dew, fog, or clouds. If the dew point is below 0°C (32°F), frost forms instead of dew. High dew points indicate moist air that can produce more precipitation. Weather forecasters use dew point to predict fog, dew, frost, and the likelihood of afternoon thunderstorms.