Estimate the air temperature from a cricket's chirp rate using Dolbear's Law. Count chirps over a timing window and get chirps per minute plus a Fahrenheit/Celsius estimate.
Results
Calculated
Estimated temperature
—
From Dolbear's Law
Chirp rate
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Scaled to chirps per minute
Alternate unit
—
Same estimate, other scale
Chirp interval
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Average seconds between chirps
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How to use the Cricket Chirp Thermometer
On a warm evening, pick out one cricket's chirping and count how many chirps you hear over a short window — 15 seconds is easiest to time. Enter that chirp count and the timing window above, choose Fahrenheit or Celsius, and click Calculate. The tool scales your count to a chirps-per-minute rate and applies Dolbear's Law to estimate the air temperature. Click Clear to reset the fields.
The formula: Dolbear's Law
Dolbear's Law states that T(°F) = 50 + (N − 40) / 4, where N is the number of chirps counted per minute. It was published by physicist Amos Dolbear in 1897 from observations of the snowy tree cricket (Oecanthus fultoni), whose chirp rate rises and falls with temperature more predictably than most insects. Since crickets are cold-blooded, their metabolism — and therefore their chirp rate — speeds up as it gets warmer. A handy shortcut follows directly from the formula: count chirps for exactly 15 seconds and add 40 to get the Fahrenheit estimate without any further math.
Interpreting the results
The highlighted card shows the estimated temperature in your chosen unit. Chirp rate is your count scaled to a full minute (chirps × 60 ÷ seconds), which is the N used in the formula. Alternate unit shows the same estimate converted to the other temperature scale. Chirp interval is the average number of seconds between individual chirps — a faster, shorter interval means a higher estimated temperature.
Frequently Asked Questions
What is Dolbear's Law?
Dolbear's Law is a formula relating cricket chirp rate to air temperature: T(°F) = 50 + (N − 40) / 4, where N is chirps per minute. It was first published by physicist Amos Dolbear in 1897 based on the snowy tree cricket, whose chirp rate tracks temperature unusually closely.
How do I count chirps without timing a full minute?
You don't need a full minute. Count chirps for any convenient window, such as 15 seconds, then enter that count and the number of seconds — the calculator scales it to a chirps-per-minute rate before applying the formula. For exactly 15 seconds, a well-known shortcut is to just add 40 to the count for the Fahrenheit estimate.
How accurate is a cricket chirp thermometer?
It's a rule-of-thumb estimate, not a precision instrument. It was calibrated on the snowy tree cricket and works best for that species; other crickets chirp at different rates at the same temperature. Wind, the cricket's age, and background noise while counting can also shift the result, so treat it as a fun approximation rather than a calibrated thermometer.
Does this work for any cricket species?
The formula was calibrated specifically on the snowy tree cricket. Other crickets and katydids also chirp faster as it warms, since insects are cold-blooded and their metabolism is temperature-dependent, but the exact chirps-to-degrees relationship differs by species, so results for other crickets will be a rougher approximation.