Soybean GDD (Heat Units) Calculator
Calculate growing degree days for soybean (base 10°C, ~1400 GDD to maturity) and estimate days to maturity from temperature.
Soybean has a base temperature of 10°C and needs about 1400 growing degree days to mature. Accumulate daily GDD from sowing to predict each growth stage and the harvest date better than the calendar can.
Indicative planning figures based on published research averages. Local soil tests, varieties and weather change actual requirements — confirm with your agronomist or extension officer.
Agronomists use the free Soybean GDD Calculator to track crop development by heat units instead of calendar days, predicting growth stages and harvest timing more accurately.
About Soybean GDD (Heat Units) Calculator
Crops develop in response to accumulated heat, not calendar days. Soybean has a base temperature of 10°C — below which it barely grows — and needs roughly 1400 growing degree days (GDD) to reach maturity. Each day adds GDD = (Tmax + Tmin)/2 − 10°C (capped at an upper threshold). This tool computes today's GDD and, from your accumulated total, estimates how many days remain to maturity at the current temperatures — far more reliable than counting days on a calendar across variable seasons.
How to use Soybean GDD (Heat Units) Calculator
- 1Enter today's max and min temperature.
- 2Optionally enter the GDD accumulated since sowing.
- 3Read today's GDD, the estimated days to maturity and the progress percentage.
Why use Soybean GDD (Heat Units) Calculator?
- ✓Uses soybean's real base temperature and GDD-to-maturity
- ✓Estimates days to maturity from temperature, not the calendar
- ✓Tracks % progress to maturity
- ✓Free, instant and fully in-browser
Frequently asked questions
What is the base temperature for soybean?+
About 10°C. Below this temperature soybean makes little or no growth, so GDD is calculated as the daily mean temperature minus 10°C.
How many growing degree days does soybean need?+
Roughly 1400 GDD from sowing to maturity, depending on variety. Accumulating daily GDD and comparing to this total predicts maturity and harvest better than a fixed number of days.
Why use GDD instead of days after sowing?+
A warm season pushes a crop to maturity in fewer days than a cool one. Heat units (GDD) capture that, so the same GDD total reliably marks the same growth stage across different seasons and sowing dates.
Is this tool free and private?+
Yes — free, no sign-up, and all calculation runs in your browser, so it works offline in the field and your data never leaves the device.
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