How Much Does Wool Shrink When Felted? Planning Sizes That Come Out Right
4 min read Intermediate
Felt shrinks by a third or more, and not evenly in both directions. How to measure your own shrinkage rate and size a project so it fits when it is finished.
Every wet felted piece comes out smaller than you laid it out. That is not a flaw — it is the process working. The problem is that "smaller" ranges from 20% to 50% depending on the wool, the water, the technique and how long you keep going, and a scarf that finishes 20 cm shorter than intended is not a scarf you wanted.
This guide covers what shrinkage really depends on and how to stop guessing.
The short answer
For most wet felting with merino tops, expect:
- 30–40% overall for a typical flat piece worked to a firm finish
- 20–25% for a lightly fulled piece such as a soft scarf
- 40–50% for a heavily fulled piece such as slippers or a structural bag
So a 200 cm layout finishing at 35% shrinkage gives a 130 cm piece. Work backwards from the size you want: divide the target by (1 − shrinkage). For a 150 cm scarf at 35%, that is 150 ÷ 0.65 ≈ 230 cm of layout.
Why it does not shrink evenly
Wool shrinks most along the direction the fibres are lying. If you laid your first layer lengthways and rolled mostly along the length, that direction will shrink considerably more than the width — sometimes twice as much.
Two consequences follow:
- Alternate the direction you roll. Roll from each end and each side in turn, or the piece will come out long and narrow, or short and wide.
- If you deliberately want more shrinkage in one direction — a fitted hat, a shaped bag — you can lay more layers in that direction and roll along it. This is a technique, not just an error.
What increases shrinkage
- Fine wool. Merino shrinks more than coarse breed wools.
- Heat. Hotter water, more shrinkage, faster.
- Temperature shock. Alternating hot and cold makes fibres contract sharply.
- Aggressive fulling. Throwing the piece, rubbing hard, using a washboard.
- Time. Shrinkage does not stop until you stop.
What reduces it
- Coarse wool, which locks quickly but contracts less.
- Fewer layers, which felt faster and full less.
- Fabric in the piece. In nuno felting, the fabric limits how far the wool can contract — though it also gathers and puckers, which is the point.
- Stopping earlier. The simplest control you have.
Make a shrinkage sample — properly
This is twenty minutes that saves a ruined project, and almost nobody does it.
- Lay out a square exactly 30 × 30 cm, using the same wool, the same number of layers and the same layout directions you plan to use for the real piece.
- Mark the fibre direction of your first layer with a wisp of contrasting colour along one edge.
- Felt and full it exactly as you intend to work the real project — same water temperature, same rolling, same finishing point.
- Dry it, then measure both directions.
A sample that finishes 20 × 18 cm tells you your shrinkage is 33% across and 40% along. Write both numbers on the sample in permanent marker along with the wool type and number of layers, and keep it. After a few projects you will have a small library that removes the guesswork permanently.
Shrinkage in needle felting
Needle felting has no water and no fulling, but wool still compacts dramatically — a loose mass reduces to roughly a third of its volume as you work it firm. That is why a needle felted ball starts about three times the diameter you want.
The difference is that needle felting compaction is under your direct control and stops the moment you stop stabbing, so it is far easier to hit a target size. You can also add wool to make a shape bigger, which wet felting does not really allow once the piece is fulled.
If a piece comes out too small
While it is still wet, you can stretch it. Pull firmly and evenly in the direction that came up short, pinning it to shape on a board if necessary, and let it dry under tension. You can typically recover five to ten percent this way — not more, and not once it has dried.
If it comes out too big
This is the easy failure. Keep fulling: more heat, more friction, more temperature shock. Felt will continue shrinking as long as you work it, so a piece that is too large is simply not finished yet.
That asymmetry is worth remembering when planning: always err on the side of laying out too much. Too big is recoverable. Too small is a coaster.
Frequently asked questions
How much does wool shrink when felted?
Typically 30 to 40% for wet felting, depending on the wool, the number of layers and how hard you full it. Fine merino sits at the top of that range and coarser wools shrink rather less.
Does wool shrink evenly in both directions?
No. It shrinks more along the direction you roll in, so rolling one way throughout produces a piece noticeably shorter than it is wide. Change the rolling direction regularly to even it out.
How do I calculate the size to lay out?
Divide the dimension you want by one minus your shrinkage rate. At 35% shrinkage, a finished length of 150 cm needs a layout of 150 divided by 0.65, which is about 230 cm.
What if my felted piece comes out too big?
Keep fulling. More heat, more friction and more rolling will shrink it further. Too small is the problem with no remedy, which is exactly why a shrinkage sample is worth the twenty minutes.
