Swim Time Conversion: SCY to LCM and SCM

American swimming runs on three pools: short course yards (25 yd), short course meters (25 m) and long course meters (50 m). The calculator below converts any swim into a pace per 100 meters — enter the true metric distance, and read the rest of this page before you treat that pace as a converted time, because it is not one.

The rule that comes before the math

USA Swimming’s Times & Recognition Policy Manual, updated 14 April 2022, is blunt about it. Section 4.6, Official Time, on page 7: “Times swum in SCY, LCM or SCM shall be uploaded to SWIMS in the relevant course. Times are not official if they are converted from one course to another.”

The manual repeats the point where meets are merged across venues — not in 4.6, but in Appendix A, Virtual Meets, item 6.c.i on page 23: “Times achieved shall be in the course swum. Times that are converted are not official and will not be accepted.”

Converted times keep exactly one narrow job, and 4.6 names it: “When used for a meet entry, a time may be submitted in a non-conforming course according to the meet announcement.” An entry time, allowed at the discretion of the meet announcement — not a record, a time standard or a qualifying mark. Every conversion tool on the internet, this page included, produces an estimate for planning, not a time.

What the arithmetic actually gives you

One part of the difference between courses is pure length, and it is exact. The international yard is defined as exactly 0.9144 meters, so:

• 100 yards = 91.44 m
• 200 yards = 182.88 m
• 500 yards = 457.2 m
• 1,650 yards = 1,508.76 m

Swim 100 yards in 50.00 seconds and you covered 91.44 m, which is a pace of 54.68 seconds per 100 m. That is a distance conversion, and it is right. It is also only half the story, because it assumes you would hold the same speed over the extra 8.56 m — and it ignores the part that actually separates the three courses.

The other half: turns, which do not scale

A 100 in a 25-yard pool has three turns. A 100 in a 50-meter pool has one. Each turn is a push off a solid wall plus an underwater phase, and both are faster than swimming. That advantage is real, and it is not the same size for every stroke — which is exactly why a single factor cannot exist.

The proof sits in World Aquatics’ own point tables, which score long course and short course separately. Reading the 1,000-point line off both 2025 men’s tables:

Event	Long course (50 m)	Short course (25 m)	Short course advantage
100 freestyle	46.40	44.84	1.56 s (3.4%)
200 freestyle	1:42.00	1:38.61	3.39 s (3.3%)
400 freestyle	3:40.07	3:32.25	7.82 s (3.6%)
100 backstroke	51.60	48.33	3.27 s (6.3%)
100 breaststroke	56.88	55.28	1.60 s (2.8%)
100 butterfly	49.45	47.71	1.74 s (3.5%)
200 individual medley	1:54.00	1:48.88	5.12 s (4.5%)

Backstroke gains more than twice what breaststroke gains, for an obvious reason: the underwater dolphin off the wall is worth a lot in backstroke and is rule-limited in breaststroke. Any “universal” SCY-to-LCM factor is averaging that spread away.

So how do you compare a yards time to a meters time?

Three defensible options, in order of how much they respect the evidence:

1. Don’t. Race and benchmark in one course, and let each course have its own personal bests. This is what the rules assume you will do.
2. Compare by points, not by seconds. World Aquatics publishes separate point tables per course precisely so performances can be ranked across them. That is the sanctioned bridge between SCY’s metric cousins.
3. Convert distance only, and say so. Use the calculator above with the true metric distance, and label the result an estimate. It will read slightly optimistic against a real long course swim, because you kept the short course turns and dropped nothing for them.

For training, the practical rule is simpler: keep every time trial and threshold test in one pool. The critical swim speed calculator is only meaningful if both trials share a course, and the swimming training zone chart inherits that pace directly. To turn a swim of any length into a comparable pace, start with the swim pace calculator.

This content is informational and does not replace coaching or the rules of your governing body.