A 31°F day, heated to 70°F.
Worked exampleNot your room
Humidity around your guitar
16–29%
That is the cracking zone. An estimate for the air around your guitar, worked out from local weather.
This is a HygroMount.
A guitar hanger with a hygrometer in the face, so the number you read is the air right at the instrument. Its display is showing that same reading, live.
It is 31°F outside at 68% humidity. Heat that same air to 70°F and it picks up no extra water on the way in, so the air around your guitar is likely between 16 and 29% humidity. Wood wants 45 to 55. Under 40 a solid top shrinks against braces that will not move, and that is how tops split.
The week ahead, where you are
Under 40 is when solid tops crack. Over 60 is when the top swells and the strings sit higher.
Get told before it happens.
We will email you when the forecast puts the air around your guitar outside 45–55%. Nothing else, and one click to stop.
Everything above is estimated from a public weather station miles from your house and run through the physics of heated air. It knows nothing about your humidifier, your radiator, or the window you left cracked. The only way to know what your guitar is actually breathing is to measure it at the guitar.
$19.99 · in stock · ships with Prime
The top has nowhere to go.
Spruce top15 inches across
Drag the humidity down and watch what winter does to a solid spruce top.
This is where wood wants to live.
At 45% the top holds the width it was built at.
The glue never gives, so the top does: a hairline crack running down from the bridge, most often in the first cold month of the year. The repair runs $200 to $600, and the instrument never quite sounds the same after.
HygroMount · in stock
Put the number on the wall.
Everything above is an estimate from local weather. The mount reads the air right at the guitar, and it ships from Amazon with Prime.
Buy on Amazon · $19.99