Almanac & sky · NUMORA
True Solar Time Calculator
Longitude vs 120°E — Ürümqi can shift a whole earthly branch.
Open interactive calculatorHow to use
Watches use zone time. Traditional hour pillars use local true solar time.
Formula
Δmin = 4×(λ − 120°) + equation of time
FAQ
Is this True Solar Time calculator accurate?
The formula and assumptions are shown on the page, and the engine is covered by audit tests. Results are for reference — not financial or medical advice.
Do I need an account?
No. Calculations run in your browser. Recents can stay on this device.
What inputs do I need?
Watches use zone time. Traditional hour pillars use local true solar time.
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