Decimal Time - Conversions

Formulas

To obtain a Julian Date from Gregorian calendar date (D/M/Y) and hours (UT): int(D-32075+1461×(Y+4800+(M-14)/12)/4+367×(M-2-(M-14)/12×12)/12-3×((Y+4900+(M-14)/12)/100)/4) + UT/24 - 0.5
From Fliegel, H. F. and van Flandern, T. C. (1968). Communications of the ACM, Vol. 11, No. 10 (October, 1968).

To find decimal dates from the tables below:
Julian Date: JDN + DOY + UT/24 - 0.5
Modified Julian Date: JDN - 2,400,001 + DOY + UT/24
Excel/PC Serial Date: JDN - 2,415,019 + DOY + h/24

Tables

Local time = UT

Standard Time to Fractional Day
Local UT UT/24 JD

Time Intervals

Decimal to HMS
1.0d = 24h 0m 0s

0.1d = 2h 24m 0s

0.01d = 14m 24s

0.001d = 1m 26.4s

0.0001d = 8.64s

0.00001d = 864ms

0.000001d = 86.4ms

HMS to Decimal
24h = 1.0d

1h = 0.0416d

30m = 0.02083d

15m = 0.010416d

5m = 0.003472d

1m = 0.000694d

1s = 0.0000115740d

Fractional Day to Standard Time
UT/24 JD UT Local

Julian Day Number
at January 1.0
CE/AD JDN

Decimal Time logo by Henning Strandin