Sidereal Year to Sidereal Day Converter

Time Converter

21 units available

Decimals:

From

To

366.256399

1 sid yr = 366.256399 sid day

Formula:

sid day = sid yr × 366.2563989345

With your value: 1 sid yr = 366.25639893 sid day

How big is that?

Everyday references on a logarithmic scale, all expressed in sidereal year so you can sanity-check the result.

Minute (1/5.3e+5 your value)0.00000190 sid yr

Working day (1/1.1e+3 your value)0.000913 sid yr

Day (1/3.7e+2 your value)0.00274 sid yr

Week (1/52 your value)0.0192 sid yr

Year (1/1.0 your value)1.00 sid yr

Your value1.00 sid yr

Other Sidereal Year to Sidereal Day conversions

2 sid yr to sid day 3 sid yr to sid day 4 sid yr to sid day 5 sid yr to sid day 6 sid yr to sid day 7 sid yr to sid day 8 sid yr to sid day

Sidereal Year to Sidereal Day Conversion Table

Sidereal Year (sid yr)	Sidereal Day (sid day)
0.5	183.128199
1	366.256399
2	732.512798
5	1,831.281995
10	3,662.563989
15	5,493.845984
20	7,325.127979
25	9,156.409973
50	18,312.819947
100	36,625.639893
250	91,564.099734
500	183,128.199467
1000	366,256.398935

Sidereal Day to Sidereal Year Conversion Table

Sidereal Day (sid day)	Sidereal Year (sid yr)
0.5	0.001365
1	0.00273
2	0.005461
5	0.013652
10	0.027303
15	0.040955
20	0.054607
25	0.068258
50	0.136516
100	0.273033
250	0.682582
500	1.365164
1000	2.730328

Where these values come from

Every factor on this page is traced to the document that defines it. See the full provenance dataset or our methodology.

Sidereal Year (sid yr)

Time

SI definition

Traceable to the second, defined by fixing the caesium-133 hyperfine transition frequency at 9 192 631 770 Hz.

Source: BIPM, The International System of Units (SI), 9th edition, 2019 (updated 2024)

Bureau International des Poids et Mesures · Reviewed 2026-07-01

Sidereal Day (sid day)

Time

SI definition

Traceable to the second, defined by fixing the caesium-133 hyperfine transition frequency at 9 192 631 770 Hz.

Source: BIPM, The International System of Units (SI), 9th edition, 2019 (updated 2024)

Bureau International des Poids et Mesures · Reviewed 2026-07-01

How to Convert Sidereal Year to Sidereal Day

To convert from Sidereal Year (sid yr) to Sidereal Day (sid day), multiply the value by 366.2563989345.

Formula: sid day = sid yr × 366.2563989345

Reverse: sid yr = sid day × 0.0027303277

Step-by-Step Example

Start with your value in Sidereal Year. For example: 5 sid yr
Multiply by the conversion factor: 5 x 366.2563989345
The result is: 1,831.281995 sid day

About Sidereal Year

The sidereal year (sid yr) is a unit of time. One sidereal year equals 3.155815 × 10^+7 seconds. UnitConvertLab converts it against every other time unit using this exact definition, so results are reproducible to full double precision rather than rounded lookup tables.

Common uses: time calculations, engineering and science, education.

About Sidereal Day

The sidereal day (sid day) is a unit of time. One sidereal day equals 86164.0905 seconds. UnitConvertLab converts it against every other time unit using this exact definition, so results are reproducible to full double precision rather than rounded lookup tables.

Common uses: time calculations, engineering and science, education.

Frequently Asked Questions

How many Sidereal Day are in 1 Sidereal Year?

There are exactly 366.2563989345 Sidereal Day in 1 Sidereal Year. This means the conversion factor from Sidereal Year to Sidereal Day is 366.2563989345.

What is the formula to convert Sidereal Year to Sidereal Day?

The formula to convert Sidereal Year to Sidereal Day is: sid day = sid yr × 366.2563989345. For example, to convert 10 Sidereal Year to Sidereal Day, you would multiply 10 by 366.2563989345.

What is a Sidereal Year?