Dew Point Calculator - Fensto

Dew point calculator with a clear answer: should you open the window now, and for how long? Fensto compares the air inside with the weather outside and tells you in one sentence.

HOW IT WORKS
Pick your place (or allow approximate location), enter the temperature and humidity from your hygrometer, and Fensto shows a traffic-light window: air now, only briefly, or better not. In summer it warns you when outside air would bring moisture into the cellar. A wall check shows how humid the surface of a cold corner gets, because indoor humidity in the middle of the room can look fine while a cold wall is not.

WHAT IS FREE
• Dew point calculator: inside, outside and at the wall
• Airing answer for one room, with weather for your place
• Airing timer with a "close the window" notification
• Wall check for the current weather
• Widget with the current answer
• Share picture and the log of the last 24 hours
Free with light ads; Pro removes all ads.

FENSTO PRO (subscription, monthly or yearly; Google Play shows the price in your currency)
• No ads: no banners, a calm screen
• 24-hour airing plan with the best hours and the night-time risk for the wall
• Airing-window notifications (at most 3 per day, between 7 and 22 h)
• Unlimited rooms, each with its own wall type
• Full log, weekly summary (litres of water aired out, hours above 60 % humidity) and PDF export
• Pro widget: next airing window and night-time risk in addition

Subscriptions renew automatically until you cancel in Google Play.

GOOD TO KNOW
Fensto works with your numbers: it does not measure the humidity itself. Airing durations are guide values based on recommendations of the German Environment Agency and co2online. Weather data: MET Norway (CC BY 4.0). Places: GeoNames (CC BY 4.0). Your rooms and your log stay on your phone. For tenants, owners, anyone fighting steamed-up windows and damp corners, and for anyone keeping an eye on indoor humidity in the cellar.

Questions? [email protected]