Calculating Duad and Dwad charts

Duads are twelve 2.5 degree segments of a zodiac sign. Each duad starts with the zodiac sign and then progresses through each of the following signs in order. E.g. If the zodiac sign is Sagittarius, then the first 2 degrees 30 minutes will be the Sagittarius duad of Sagittarius, the second 2 degrees 30 minutes will be the Capricorn duad of Sagittarius, the third 2 degrees 30 minutes will be the Aquarius duad of Sagittarius .. and so on.  (Click to see Duad Table )

There is a second kind of division where the 1st dwad of any sign is the Aries dwad, the 2nd is the Taurus dwad .. and so on.  These are easy to calculate on a computer because they are the 12th harmonic chart.


As each duad is a “mini sign” the 2½ degrees it covers can be converted into the 30 degrees of a normal zodiac sign and make a whole new duad chart. It is relatively simple to calculate the duad zodiac degree by taking the start of the duad degree away from the degree of the planet and then converting that degree into the zodiac degree within that duad.

For example: Adam’s natal Sun is 8Scorpio23. This is the Aquarius duad of Scorpio and that duad starts at 7.30° Scorpio

08.23 – 07.30 = 0.53

So Adam’s Sun duad is 0° 53’ into the Aquarius duad. Using a calculator that calculates in units of 60, you can multiply 0° 53’ x 12 and this will give you 10°.36’ Therefore Adam’s duad Sun is 10° 36’ of Aquarius.

You can follow the same method for all the other planets and angles in the chart to make up a duad chart.  The duad chart has the Ascendant in the same position as that of the natal chart,  but the MC and IC can be in any house in the duad chart.   Mercury and Venus can be anywhere in the duad chart, they don’t have to be close to the Sun.

Following this the dwad chart is quite easy to calculate as the planets and angles will be in the same degree as that of the duad chart, but usually in a different dwad sign.


Australian research astrologer Ray Murphy has been kind enough to design this little duad calculator for me.  All you have to do is put in the degree and sign of each planet and it will automatically calculate its duad position.  If you want to use it you will need to download it to your own computer, save it  and then open it.


Highlight the planet then enter its degree and minute, then click its sign. Continue doing this until all planets and angles have been covered and then click the Calculate button under the DUADS column.   The program will automatically calculate the duad.


Esoteric Technologies were kind enough to incorporate the calculation of duad charts in their program.

To calculate the duad chart, highlight the natal chart on the first page of Solar Fire, then go to the “Chart” menu, click Vedic and then Vedic D12 Dwadashama. Click OK. The computer will ask you if you want to use Vedic settings click NO and you will have your duad chart.

To calculate the dwad chart, go to the Chart menu on the top left hand side, then click ‘Harmonics, Transform..’ then click Harmonic Chart.  In the box above titled ‘Harmonic’ put in 12 and then click OK.  You then have the 12th harmonic chart, which is the dwad chart.

Copyright (c) Alice Portman 2009

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