Why does my tent get wet inside?

Each person exhales roughly 500ml of moisture per night through breathing and perspiration. In a sealed tent, this moisture has nowhere to go and condenses on the coldest surface — the inner walls or flysheet. Cold temperatures and high humidity make this worse.

How do I prevent tent condensation?

Keep vents open, even in cold weather. Avoid cooking inside. Use a double-wall tent where the inner mesh allows moisture to pass through. Position your tent to catch a light breeze. Avoid camping next to water sources which raise local humidity.

Is a double-wall tent better for condensation?

Yes. Double-wall tents have a breathable inner tent and a separate waterproof flysheet. Moisture passes through the inner and condenses on the fly instead of dripping on you. The air gap between layers also provides insulation. Single-wall tents condense directly onto the wall beside you.

What is the dew point?

The dew point is the temperature at which air becomes saturated and moisture begins to condense. When the tent wall temperature drops below the dew point, condensation forms. Higher humidity means a higher dew point, making condensation more likely.

CampCalcs

Tent Condensation Calculator

Predict condensation risk inside your tent based on conditions and occupancy.

Number of Occupants

Enter the number of occupants

Tent Type

Tent dimensions

Ventilation

Enter the ventilation

Overnight Low Temperature

Temperature for this process

Relative Humidity

Typical UK overnight: 70-90%

How We Calculate This

Condensation Risk

Risk is calculated from temperature proximity to dew point, number of occupants, tent type, ventilation level and ambient humidity.

Moisture Output

Total moisture = Occupants x ~500ml per person per night

Dew Point

Calculated using the Magnus formula from temperature and relative humidity.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Always verify conditions and use proper safety equipment outdoors.