SCM vs LCM — two pools, two clocks
Short course metres (SCM) is a 25-metre pool. Long course metres (LCM) is a 50-metre pool — the Olympic length. Irish heat sheets write SC or LC in the title. That letter is which race you watched.
In the United States you will also see short course yards (SCY) and a different converter again. In Irish club swimming you can almost ignore yards. You cannot ignore 25 versus 50. A time without a course is a rumour, and a conversion of a rumour is still a rumour.
This page is the conversion explainer: what the software is doing, why the number is only an estimate, and what you must never do with it at home. The Irish season and the two clocks: short course vs long course. What counts as a personal best versus an official result: PB vs official time.
Why turns make short course faster
Turns. Not a softer field, not winter form, not a calculator inventing speed. A push-off and underwater swimming are faster than surface stroke, and the wall breaks the cycle. Swimmers are quicker in 25m because they spend more of the race turning and gliding.
A 100 in a 25-metre pool has three turns; the same 100 in a 50-metre pool has one. Elite short-course times often sit about two to three per cent quicker. A strong underwater stretches that; a weak turn shrinks it. Stroke and distance matter — which is why a single “convert my time” box is a blunt instrument. Long course is not a harder child. It is more swimming between walls. A converter is trying to guess how much those extra walls were worth. Guess is the honest word.
What a conversion actually is
A conversion is maths applied to a time from the other course. You hold a 25m 100 free. The gala is 50m. The software — or a website, or a parent with a spreadsheet — runs the time through a factor and prints a long-course estimate. The child did not swim that number. It is a translation of a race that happened in a different pool.
That translation has a job. Hosts need to sort a mixed field. Without a conversion, half the heat sheet is a guess in the other direction — or a pile of NTs. So the software converts for seeding, and at some Irish meets for entry. The seed on the sheet may be a converted number. That is what a seed time is: last best used to place the heat, not today’s result.
| Kind of number | What it is | Can it seed a heat? | Is it a PB? |
|---|---|---|---|
| Official SC time | Swum in 25m, licensed, on the clock | Yes, for a 25m gala | Yes — the SC PB, if it is last best |
| Converted LC estimate | That SC time, run through a factor | Often, if the pack allows it | No. Never |
| Official LC time | Swum in 50m, licensed, on the clock | Yes, for a 50m gala | Yes — the LC PB, if it is last best |
What Hy-Tek and meet software actually do
Most Irish start lists come out of Hy-Tek Meet Manager. The same family of software runs a huge share of USA Swimming and club meets. It has a convert function. Irish paperwork calls the output Hy-Tek conversions. The host — or the club Team Manager — can turn a 25m time into a 50m estimate, or the other way, so a mixed field can be sorted.
That is a seeding tool. At some championships it is also an entry tool: the consideration time is in 50m, you only hold 25m, the pack says a Hy-Tek conversion is accepted. Read the pack. The conversion that gets them on the start list is still not the time they will put on the clock, and it is still not a PB on the course they have not raced. After they race, the official result is the time in this pool. The converted seed was the “before.” It was never the “after.”
If you know the seed was converted, put a C beside it. After the race, log the official time against today’s course. Two rows if you must. The conversion seeded the heat. The PB list stays on the swim they did.
Published factors are estimates — not a Swim Ireland formula
The factors inside Meet Manager are not magic unique to Ireland. They sit in the same family as published conversion tables — USA Swimming motivational conversions are the ones people Google — and similar tables used by other federations and websites. Multiply (or divide) the official time by a factor for that event. Different stroke, different distance, different factor. Those tables describe an average gap. They do not describe your child’s underwaters on a tired Saturday in January.
I am not going to invent an “official Swim Ireland formula.” There isn’t one on this page, and you should not copy a number out of a US table and call it Irish qualifying maths. If a meet pack says “Hy-Tek conversion accepted,” it means the host will use the software’s table for that meet. If the pack says no conversions, believe it.
Do not treat a website converter as a qualifying time. Do not screenshot 1:10.83, write “LC PB,” and send it to the Team Manager as if they swam it. The pack either wants a real 50m time or it will convert the 25m time itself. Your phone is not Meet Manager.
An illustration — not a qualifying time
I will show the arithmetic once, so the group chat has a picture. Then I want you to forget it as a number you own. Take a swimmer whose official short-course 100 free PB is 1:08.42. A common 100 free factor of the sort meet software applies is long course × 0.966 ≈ short course. Turning that around: 68.42 seconds ÷ 0.966 ≈ 70.83 seconds — 1:10.83 as a converted LC guess.
| Number | Time | What it is |
|---|---|---|
| Official SC PB | 1:08.42 | Swum in 25m. This stays the short-course best. |
| Converted LC estimate | 1:10.83 | Maths. May seed a 50m heat. Must not enter the LC PB column. |
| First official LC swim | 1:11.18 | Swum in 50m. This is the long-course baseline — a real time, a different clock. |
Same invented 100 free as the tracking and season guides. Your child’s gap will differ by stroke, underwaters, and the day. Do not save 1:10.83 as a long-course personal best.
Illustration only. The green bar uses a common 100 free factor of the sort meet software applies for seeding — not a prediction and not a qualifying time. Bars start at 1:05.00 so the gap is visible.
Which Irish championships refuse conversions
This is where families get caught. Some championships will take a Hy-Tek conversion for entry. Some will not. I am staying with the 2025–26 notes already on short course vs long course — check the current pack, because this moves.
On those notes, Irish Open and the Irish Summer National Youth & Senior Championships wanted long-course times only — no short-course times, no short-course conversions. A converter in your pocket does not get them on that start list. They need a real 50m time inside the window, at the right licence. Other 2025–26 championships (regionals, Winter Nationals, McCullagh, Summer Age Group) did accept Hy-Tek conversions for entry. That still does not make the converted number a PB. It makes it an allowed seed.
If the target meet wants 50m and refuses conversions, the job is to race 50m in the window — not to massage a winter PB until a website agrees. Write the course on the goal. Then go swim it.
Never overwrite a short-course PB with a conversion
This is the rule that saves the list. You hold 1:08.42 SC. A converter says 1:10.83 LC. You do not delete 1:08.42. You do not replace it with 1:10.83. You do not keep one “best 100 free” that jumps between pools. You keep two rows: short-course best, long-course best. When they finally swim 1:11.18 in a 50-metre pool, that number opens the long-course column. It does not touch December. Overwriting is how an honest season looks broken. Last best is a history of races, not a history of arithmetic.
- ✓Write the course on every time. No blank course column.
- ✓Keep a short-course best and a long-course best for the same event.
- ✓Mark converted seeds as converted. Never promote them to PB.
- ✓If the championship refuses conversions, you need a real time in that course.
- ✓After the race, log what they swam today — not what the converter predicted.
How to run the list is how to track swimming times. What a PB is, versus the official result, is PB vs official time. This page is only the conversion rule: the estimate can seed a heat. It cannot steal a column.
Finzy does not auto-convert
I built Finzy so a family can keep those two personal bests apart. We do not pretend a calculator can turn one clock into the other. Finzy does not auto-convert. You type the swim you actually did. Short-course PBs and long-course PBs live as separate rows. If you want a converted seed on the record, write it in the notes: “converted seed for McCullagh entry.” The PB column stays on the race. Store both course PBs separately. Never overwrite SC with a conversion.
A converted time is a seed guess, not a swim. Keep two PBs. Type the race they actually did. Never let the converter steal the short-course column.
