There are a few variations of the skirt block; you could have a Skirt Block with
- 2 darts in both the front and back,
- 1 dart in the front and 2 darts in the back, and
- 1 dart in both the front and the back.
The bigger the difference between your waist measurement and your hips, the more darts you need to have a well fitting skirt.
On this website the standard block (for which instructions are given) is the 2-Dart Skirt Block that has 2 darts in both the front and the back. More darts allows more contouring, and this block can be used to make both straight skirts and flared skirts.
The 1-Dart Skirt Block here has only 1 dart in both the front and back. This is used most often for creating slinky skirts that hug the upper hip and hip, then flare out below the hip - these skirts are cut on the bias. Like any derivative block, the purpose of creating it is simply to save time doing the same steps each time you make a pattern; e.g. if you make one slinky skirt you have to go through the steps in these instructions to create it - if you create a derivative block, next time you won't have to repeat these steps.
Of course the 2-Dart Block can also be used to make flared skirts; which block you use will depend on the style of skirt you are wanting to create - see the example further down below.
Note that the 1-Dart Skirt Block has the total waist dart value distributed equally between the front and the back. When closing the one dart and using pivot points lower than the dart point, differing levels of hip-hugging can be achieved.
In this image the left flared skirt is created from a two-dart block that has had both the darts closed, pivoting on the dart points to close the darts and create flare. To the right is a flared skirt that is created from a one-dart block and the pivot point has been lowered. What you should notice is that the skirt created from the two-dart block has a lot of ease added in the hip area in the process of creating the flare, whereas the one created from the one-dart block does not. The flare in the skirt to the right will all be below the hip, not around the hip.