Time Converter: how we convert swim times

Step by step

Web app Mobile app

Convert any time

1. Coaches: click Meets, then the Time Converter tab. Parents: click Results, then Time converter.
2. Under Your swim, type the time. 1:02.34, 62.34 and just the digits 10234 all work. One or two digits, like 28, means whole seconds.
3. Pick the Stroke, the Distance and where it was Swum in (SCY, SCM, LCM or Custom for any pool length in yards or meters).
4. Under Convert to, each pool already shows its converted time. Click one to see it big, with the breakdown underneath.
5. Want to go the other way? Click the round swap button.

Convert a swimmer’s time

1. Hover any time on a swimmer’s page, in Top Times, meet results and meet reports, records, the Best Times Grid, qualifying times or meet entries.
2. Click the … that appears next to it. You’ll see the time converted to the other pools right away.
3. Click a pool, or Open time converter, to see the full breakdown. Everything is filled in already, and you can change any of it.

In time pop-ups (like the one that opens when you click a best time), use the Convert time button. In the entries Grid, click an entered time and choose Convert time.

Make it more accurate

1. Open Swimmer under the result. Set their Age and Sex if they aren’t filled in. If age is blank, we treat it like an adult’s swim, and kids get less from each wall than adults do.
2. Set Underwaters to how good they are off the walls compared with swimmers their age and speed: Below avg, Average, Good or Elite.

What changes between pools

A converted time is not just the distance swapped from yards to meters. Three things change, and the converter shows you each one under Why this time.

1. Distance. 100 yards is 91.44 meters, so a 100 in meters is about 9% farther. That’s the biggest piece.
2. Walls. A 100 in a 25 yard pool has 3 turns. In a 50 meter pool it has 1. Every wall gives you a push off and an underwater that is faster than swimming. Fewer walls means a slower time.
3. Pace. A longer race is swum at a slightly slower average speed. When the distance grows (yards to meters) or shrinks (500 yards to 400 meters), pace changes a little too. Swimmers also go a little faster in yards pools than distance and walls explain, and that shows up here (more on that below).

The race strip under the result draws both pools to scale, with a tick for every wall, so you can see it.

Why the usual conversion tables miss

Most meet software uses the same factor table that has been around for decades. It multiplies by a fixed number (1.11 for yards to meters) and adds a fixed number of seconds for every turn you lose. The seconds are set by stroke: 0.8 free, 0.6 back, 1.0 breast, 0.7 fly.

That works well for one kind of swimmer: a fairly fast high schooler. It breaks down at both ends.

• Fast swimmers. The table says a backstroke wall is worth 0.6 seconds, the least of any stroke. World records say the opposite. Elite backstrokers gain about 1.6 seconds from every extra wall, because their underwater kick is so much faster than swimming on their back. The old table misses the men’s 100 back world record by over two seconds.
• Young swimmers. A fixed multiplier blows up long, slow swims. And a 9-year-old’s turn is not an Olympian’s turn.
• Everyone in between. One number per stroke can’t know how far you push off, how long you stay under, or how tired you are by the last 50.

Our models

You can pick the model under Compare models, and see all of them side by side. Our own model is the default.

Commit Turn Model (ours)

This model rebuilds the race wall by wall:

race time = distance ÷ swimming speed − time gained at each wall − time gained on the start

To convert, it works out the swimmer’s speed between the walls from the time they swam. Then it rebuilds the same race in the new pool, with the new distance, the new number of walls and the new pace.

How much each wall is worth depends on:

• The stroke you leave the wall in. Each wall in an IM counts as the stroke that comes next.
• The race distance. In freestyle and butterfly, a wall is worth a bit less in long races as swimmers tire. In breaststroke it’s worth more in the 200, because the swimming between walls is slower.
• Speed. How fast you swim, compared with the world record for your event and sex, tells us a lot about your turns. If sex isn’t set, we compare with the middle of the men’s and women’s records.
• Age. Older swimmers get more from a wall at the same speed. Stronger legs mean faster push offs. If age isn’t set, we use adult turns.
• Underwaters, if you set them.

We started from world records in both long and short course, so the model is right at the top end. Then we tuned it on about 20,000 pairs of real swims from Commit teams: the same swimmer, same event, two different pools, within 30 days of each other.

What the data taught us:

• Every stroke uses its walls differently. In freestyle, a wall is worth a little more to faster swimmers. In backstroke and butterfly, it’s worth roughly the same at every speed. In breaststroke, slower swimmers gain the most by far, because the pullout is so much faster than their stroke on top of the water. One number per stroke can’t capture that.
• Age matters on its own. At the same speed, a 10-year-old gets about 30% less from each wall than a 16-year-old. That’s leg strength and underwater skill.
• Yards pools swim fast. Times in yards come out about 1.8% faster than distance and walls alone explain. We see it at every level, from 10-year-olds to NCAA records. It’s likely the deep, fast pools and the fact that most US swimmers peak in yards season.
• Underwaters vary a lot. Among swimmers of the same age and speed, the top 5% gain about twice as much per wall as a typical swimmer. The bottom 20% gain about 30% less. That’s what the Underwaters setting controls.

Commit Peer Percentile

A completely different approach. It finds where the time ranks among swimmers of the same sex and age group in our results, then gives the time with the same rank in the other pool. If your 11-year-old’s 100 free is faster than 80% of 11-12 girls in yards, it shows the long course time that’s faster than 80% of 11-12 girls in long course.

We rank season bests from about 10 million swims, using swimmers who raced in more than one kind of pool that season, so both lists come from the same group of swimmers. This model needs the swimmer’s sex, only covers SCY, SCM and LCM, and only covers times inside the range of our data. If age isn’t set, we don’t have enough swims for that age group, or the time is outside that age group’s range, it ranks the time against all ages.

Hy-Tek / USA Swimming

The classic factor table described above. It’s what most meet software uses, and it’s what Commit still uses to check meet qualifying times and to build entry files. Meet hosts set their rules with this table, so we match it there.

British Swimming Equivalent Time

The published UK method. It treats a wall as worth more to faster swimmers, and it covers odd pool lengths like 20 yards and 33⅓ meters. It only converts the same event between pools, so it skips 500 yards ↔ 400 meters.

How accurate is it?

We tested every model on 134,000 pairs of swims from swimmers the model had never seen, converting each pair both ways. This is how far off each model was from what the swimmer actually swam in the other pool (median miss):

Keep in mind that even a perfect converter misses a little. The same swimmer, in the same pool, a few weeks apart, swims about 1.9% different at the median. Swimmers have good days and bad days, taper for some meets and not others, and improve week to week. Once you take that out, the Turn Model’s error is about 30% smaller than the standard table’s.

It also holds up at the very top. Converting long course world records to short course:

Custom pools

Pick Custom and enter any pool length from 10 to 100, in yards or meters. The converter counts the walls for that pool. It blocks events that don’t fit, like a 50 in a 33⅓ meter pool, or a 200 IM that would put a stroke change in the middle of a length.

Common questions

Does this change my meet entries? No. Entries and qualifying checks still use the Hy-Tek table, because that’s what meets use.

Why do the models disagree? They’re built different ways. When they agree, you can be confident. When they’re far apart, the swim is in an area where the old tables are weakest, like very young or very fast swimmers.

What about relays and diving? The converter is for individual swims.

Can people outside Commit use it? Yes. The same converter is free for anyone at commitswimming.com/swim-time-converter.

Why does “Elite” underwaters make the long course time slower? In long course there are fewer walls. A swimmer with great underwaters loses more when the walls go away, so their long course time converts slower. It works the other way when you convert long course to short course.