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Daylight Saving Adjustment Calculator

Work out daylight saving adjustment instantly with clear inputs, formula shown and shareable results.

About Daylight Saving Adjustment Calculator

Spring forward moves clocks ahead, so 09:00 standard becomes 10:00 and one hour of the night is lost; autumn back does the reverse and returns it. The lost hour in spring measurably raises road accidents and cardiac events for a few days, which is why the practice remains contested.

Formulas

Spring forward

adjusted = standard + shift

Autumn back

adjusted = standard - shift

Worked example

With the default values below, Daylight Saving Adjustment Calculator returns Time After The Change of 10.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Standard timeaccepts 0–23 h
9 h
Adjustmentone of Spring forward (clocks go ahead), Autumn back (clocks go back)
Spring forward (clocks go ahead)
Size of the shiftaccepts 0–2 h
1 h

Results

Time After The Change
10.00 h
Adjusted Clock Time
10:00
Change In Available Sleep
-1.00 h
Day Shift
0

Step by step

  1. 1Values used
  2. 2Spring forward
  3. 3Autumn back
  4. 4Time After The Change= 10.00 h
  5. 5Adjusted Clock Time= 10:00
  6. 6Change In Available Sleep= -1.00 h
  7. 7Day Shift= 0

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Do all countries change clocks?

No. Most of Asia, Africa and the tropics do not, since the seasonal daylight variation near the equator is small.

Why is the shift usually one hour?

Convention. Lord Howe Island uses 30 minutes, and some wartime schemes used two hours of double summer time.

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