Relays Over The Last 10 Years: Women’s 4×100 Free

2025 World Championships

• July 27 – August 3, 2025 (pool swimming)
• Singapore, Singapore
• World Aquatics Championships Arena
• LCM (50m)
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With the Singapore World Championships fast approaching and speculation over relays building, what have the finals for each relay looked like over the last decade?

That takes into account eight world-level international summer meets, and we’ll take a look at the women’s 4×100 free here.

As a preview of what is included here, we’ll go through:

• Which nations have been in the final each year
• The nations with the most appearances
• How the final time for each finals position has changed
• How the finals time compares to that countries cumulative time heading into the meet
• How Swimswam’s predictions have fared over the years

We’ll also take a look at the continuity of each final – for a recap of how we calculate this take a look at the methodology explained in this previous article.

The Data

The cumulative times are taken from the calendar year best heading into the World Championships or Olympics of the top four individuals for each nation.

The calendar year best here is used for convenience. Far more of the data processing required here was manual than in an ideal situation, and finding season bests would slightly more than double that. 

Additionally, there would come the decision on how to define when the season ends. For Asian nations this is often into the early-to-mid autumn, especially in an Asian Games year, compared to pretty much immediately after the summer meet for European and American swimmers. Using the calendar year best is a cleaner delineation, and the times should be more pertinent to the summer relays as well than those at the start of the season.

These may not necessarily be the swimmers that swim in the relay,and the drops may be due not only to internal improvement but a new swimmer or two.

Additionally, the data here is not 100% complete. The World Aquatics results database used is probably the best for blanket global coverage to the depth required each year, but there are gaps. Most major and national meets are captured, but results from medium to small meets are generally not.

For example, Carson Foster’s 4:08.46 400 IM that he swam at the 2021 Southern Sectionals is not in the database, despite it being the fastest 400 IM time in the world that year.

The result of this is that the cumulative data here is not quite perfect – there are likely a few of the cumulative times that would be slightly faster due to a swim that we’ve not managed to find.

However, with the volume of data and the fact that we’re looking to make general rather than specific conclusions, this should not have a material effect on what we see.

The Finalists

Australia have been dominant over the last decade, only being beaten in 2017. The U.S. is the only other nation to have been on the podium every time, with China now seemingly replacing Canada as the main challenger to the top two.

There have been six nations to be in at least seven of the eight finals. European powerhouses Sweden and the Netherlands have been consistently in the middle of the final, although the former will likely miss out this year with Sarah Sjoestrom, a big reason behind that streak, not in Singapore.

Great Britain are on a four-year final streak, although they are yet to have anyone break 54 seconds this season and have lost 52-flat split Anna Hopkin.

How Have The Finals Times Changed

The battle for silver has been a close battle recently, but at the front Australia have been a class apart – they have won by at least a second four years running.

The time each relay team drops in the final compared to their pre-meet add-up can be seen below.

There is even less of a relationship than on the men’s side, and the time dropped appears pretty independent of the cumulative time – that trend line is very nearly flat.

What might 2025 Look Like?

For 2025, the add-ups for some of the countries aiming to be in the final this year are as follows. It took a time of 3:36.28 to make the final in Paris – there are six teams with an add-up faster than that this year.

Continuity and SwimSwam’s Predictions

Due in part to those six nations returning almost every year, there has been minimal turnover in this event. The top five finishers have always made it back into the final the next year, although Sweden, 5th last year in Paris, may be the first not to.

Finally, here’s how our predictions have fared. Blue marks the countries where we were within a single position in our predictions, with red denoting those that made the final but where our predictions were slightly further away.

We did not have a full set of relay predictions in 2015, so this year has been omitted