Crickets Chirping Thermometer

Bio-Acoustic Meteorology & Dolbear's Law

Published in 1897 by American physicist and inventor Amos Dolbear in The American Naturalist, Dolbear's Law describes the linear relationship between the chirping rate of the Snowy Tree Cricket and ambient temperature.

Primary Temperature Chirping Formulas

• 15-Second Rule (Standard US): T_^ = N_15s + 40

• Dolbear's Original 1897 Formula: T_^ = 50 + N_60s - 404

• 8-Second Metric Celsius Rule: T_^ = N_8s + 5

• 25-Second Metric Rule: T_^ = N_25s3 + 4

Biological Accuracy Limits

• Accurate between 55^ and 100^ (13^ to 38^).

• Below 50^ (10^), cricket enzyme activity slows and chirping ceases.

How to Use This Calculator

Enter your Number of Chirps Counted (e.g. 32) and Counting Time Interval — choose from Counted in 15 Seconds (T°F = Chirps + 40), Counted in 14 Seconds (Field Cricket T°F = Chirps + 40), Counted in 1 Full Minute / 60s (Dolbear's 1897 Law). Results update instantly as you type — adjust any value to compare scenarios.

The Formula

Formula Reference: Crickets Chirping Thermometer

Input variables:

chirpCount — Number of Chirps Counted

timeIntervalSelect — Counting Time Interval

Computed outputs:

temperatureFahrenheit — Estimated Temperature (°F)

temperatureCelsius — Estimated Temperature (°C)

temperatureKelvin — Estimated Temperature (K)

chirpsPerMinute — Chirp Frequency

Mathematical relationships extracted from calculation logic:

tf = count + 40.0

tc = (tf - 32.0) / 1.8

cpm = count * 4

tk = tc + 273.15

Standard: NIST Handbook 44 and BIPM SI unit definitions

Worked Example

Sitting on a summer evening hearing 32 chirps in 15 seconds from a snowy tree cricket tells you the outdoor evening air is a pleasant 72 °F.

Understanding Your Result

Unit conversion precision: round to the same number of significant figures as your original measurement. Converting 6 feet to meters gives 1.8288 m — but if your measurement was approximate (±1 inch), expressing more than 2 decimal places is false precision. For international trade and technical specifications, SI units (meters, kilograms, liters) are the standard. US customary units (feet, pounds, gallons) differ from Imperial UK units: 1 US gallon = 3.785 L vs. 1 UK gallon = 4.546 L.