The Boys 17-18 LCM record book contains some of the most recognizable names in American swimming history. Michael Phelps holds the 200 free, 200 IM, and 400 IM from 2003. Caeleb Dressel's 50 free from 2015. Thomas Heilman's 100 fly, set just last year. Campbell McKean's sprint breaststroke marks from 2025. And Luca Urlando's 200 fly from 2019.

The result is a mixed landscape: some records that were set at a generational level and remain comfortably protected, and a few — particularly in the IM and breaststroke — where the current field is projecting into genuinely competitive range.

Baylor Stanton is the multi-event story, appearing across backstroke, breaststroke, and IM with projections that clip or approach several marks. Collin Holgerson appears across five events and leads on real performance in several. And Kai Joyner anchors the distance free picture.

As with other age groups: classical backstroke conversion can be aggressive. Last-season LCM references are the more reliable measure in those events, and that context is flagged where relevant.

Sprint Freestyle

50 Freestyle — NAG: 21.53 | Caeleb Dressel (2015)

Dressel's 50 free has been on the books for over a decade. Albert Smelzer (18) leads at 19.26 SCY (22.18 projected, +3.02%), with a last-season LCM reference of 22.68 — 1.15 seconds and 5.34% above the record in actual competition. Mike Rice (18) and Jordan Ragland (18) both project to 22.20, with last-season LCM references of 23.00 and 23.04 — further back in real terms.

Smelzer's 22.68 leads the field in real competition — 1.15 seconds above Dressel's record. In the 50 free at this age, that gap is meaningful. The record is protected.

100 Freestyle — NAG: 48.38 | Maximus Williamson (2023)

This event has the tightest projections in the sprint picture. Jordan Ragland (18) leads at 42.24 SCY (48.49 projected) — just 0.11 seconds and 0.23% above Williamson's 2023 record on paper. His last-season LCM reference of 51.02, however, puts him 2.64 seconds above the record in actual competition — a substantial gap that reflects the conversion challenge in the sprint 100 free. Liam Carrington (18) follows at 48.58 projected (+0.41%), with a 51.38 last-season LCM reference. Mike Rice (18) rounds out the group at 48.75 projected (+0.76%), with the most advanced real 100 free LCM time at 49.84 — already sub-50 in long course last summer.

Rice's 49.84 last-season LCM time is the most developed real baseline in this event — already under 50 seconds in actual competition, and 1.46 seconds above the record. The projections for Ragland and Carrington look tight on paper, but their real references are the honest measure. Rice is the most credible real-world threat.

Distance Freestyle

200 Freestyle — NAG: 1:45.99 | Michael Phelps (2003)

Phelps's 200 free has stood for 23 years. Liam Carrington projects to 1:46.30 — just 0.31 seconds and 0.29% above the record on paper. His last-season LCM reference of 1:55.52 (+8.99%), however, reveals a very large projection-to-reference gap — nearly 9 seconds in the 200 free, which reflects how early in his long course development this event may be. Hayden Vicknair (17) projects to 1:47.81 (+1.72%), with a last-season LCM reference of 1:54.92. Nathan Foucu (18) rounds out the group at 1:47.88 projected, with a last-season LCM reference of 1:51.48 — the most grounded real baseline in this event, already sub-1:52 in actual competition.

Foucu's 1:51.48 last-season LCM time is the most credible real reference — 5.49 seconds and 5.18% above Phelps's record in actual competition. Carrington's projection looks striking at 0.29%, but his last-season reference is 9 seconds back — a gap that makes the projection a ceiling rather than a forecast. Phelps's record is well protected.

400 Freestyle — NAG: 3:46.01 | Ryan Erisman / Ethan Ekk (2025)

A 2025 co-record with maximum recency protection. Maxwell Stanislaus (18) leads at 3:49.28 projected (+1.45%) with no last-season LCM reference available. Trent Allen (17) follows at 3:49.41 projected (+1.5%), with a last-season LCM reference of 3:52.40 — 6.39 seconds and 2.83% above the record in actual competition, the most grounded real 400 free baseline in this group. Ellis Crisci (17) rounds out the group at 3:49.43 projected, with a 3:54.02 last-season LCM reference.

Allen's 3:52.40 last-season LCM reference is the most relevant real benchmark — within 6.4 seconds of a mark set just months ago. The record has recency protection on top of real margin, but Allen and Crisci both project under 3:50, which is worth tracking through the summer.

800 Freestyle — NAG: 7:45.19 | Luke Whitlock (2024)

Inyoung Kim (18) projects to 7:47.02 — just 1.83 seconds and 0.39% above Whitlock's 2024 record on paper. His last-season LCM reference of 8:36.44, however, puts him over 51 seconds above the record in actual competition — the largest projection-to-reference gap in the entire boys dataset. That 51-second gap effectively makes the projection a theoretical conversion output rather than a real competitive forecast. Colin Jacobs (17) follows at 7:51.44 projected (+1.34%), with a far more credible last-season LCM reference of 8:01.99 — 16.8 seconds above the record in real competition. Trent Allen rounds out the group at 7:54.41 projected, with an 8:04.30 last-season LCM reference.

Jacobs's 8:01.99 and Allen's 8:04.30 are the honest real-world baselines in this event — both within 20 seconds of Whitlock's 2024 record in actual competition. Kim's projection is a mathematical output of his SCY speed, not a forecast of LCM performance. The record is protected, but Jacobs is the swimmer with genuine long course 800 free form.

1500 Freestyle — NAG: 14:45.29 | Larsen Jensen (2004)

A 2004 record that has lasted over two decades. Gabriel Manteufel (18) leads at 14:57.81 projected (+1.41%), with a last-season LCM reference of 15:15.08 — 29.79 seconds and 3.36% above Jensen's record in actual competition. Ellis Crisci (17) and Colin Jacobs (17) project around 15:04–15:05, with Crisci's last-season LCM reference of 15:20.93 the more developed real baseline.

Manteufel's 15:15.08 last-season LCM time is the most advanced real reference — nearly 30 seconds above a 22-year-old record. The projections are encouraging, but this is an event where real long course performance will matter most when the summer season arrives.

Backstroke

Classical backstroke conversion note: projections in the 50, 100, and 200 back clip the records on paper. Last-season LCM references — which are 3–10% above the marks — are the more reliable guide to where this field stands.

50 Backstroke — NAG: 24.63 | Michael Andrew (2017)

All three candidates project under the record — Collin Holgerson at 23.75 (-3.57%), Benjamin Jaggers (18) at 24.23 (-1.62%), Erkhes Enkhtur (18) at 24.37 (-1.06%). Last-season LCM references of 25.64, 26.11, and 26.09 put the real picture in focus: all three were 1.01–1.48 seconds above the record in actual competition.

Holgerson's 25.64 is the most developed real sprint back reference — about 1 second above the record. The gap is real in a 50 back at this level. Classical conversion significantly flatters the projections here.

100 Backstroke — NAG: 53.27 | Daniel Diehl (2022)

Collin Holgerson projects to 51.08 (-4.11%) — well under the record on classical conversion — with a last-season LCM reference of 55.19 (+3.6%). Davis Jackson (17) projects to 52.15 (-2.1%), with a 55.43 last-season LCM reference (+4.05%). Baylor Stanton rounds out the group at 52.39 projected (-1.65%), with a 56.13 last-season LCM reference.

All three candidates were 1.92–2.86 seconds above Diehl's record in last-season LCM competition — that's the real picture. Holgerson leads in real terms at 55.19. The backstroke conversion issue is most pronounced in this event.

200 Backstroke — NAG: 1:55.15 | Aaron Peirsol (2002)

The 200 back is where backstroke projections and real references are most aligned in this dataset. Davis Jackson (17) projects to 1:52.58 (-2.23%), with a last-season LCM reference of 2:01.22 (+5.27%). Collin Holgerson projects to 1:53.11 (-2.04%), with a last-season LCM reference of 1:59.45 (+3.73%) — the most advanced real 200 back LCM time in the group. Baylor Stanton follows at 1:53.17 projected, with a 1:59.60 last-season LCM reference (+3.86%) — nearly identical to Holgerson's.

Holgerson's 1:59.45 and Stanton's 1:59.60 are both within 4% of Peirsol's 2002 record in real competition — the most credible real backstroke references in the boys field. The record still has meaningful protection, but both swimmers are operating at a level that merits attention over the next cycle.

Breaststroke

50 Breaststroke — NAG: 26.90 | Campbell McKean (2025)

A 2025 record with maximum recency protection. The top three candidates all project in the 27.84–27.88 range — roughly 3.5% above the record. Jake Lloyd (18) is the standout on real performance: his last-season LCM reference of 27.79 (+3.31%) is actually slightly faster than his own projection of 27.88, and it's the closest any candidate gets to the record in real competition. Austin Carpenter (18) and Andrew Eubanks (18) have no last-season LCM references available.

Lloyd's 27.79 last-season LCM time is the most relevant real data point — already 0.89 seconds above McKean's very fresh record. The record is protected by its recency, but Lloyd is the most credible real sprint breast reference in this field.

100 Breaststroke — NAG: 58.96 | Campbell McKean (2025)

Another 2025 McKean record. Collin Holgerson leads at 51.75 SCY (59.44 projected, +0.81%), with a last-season LCM reference of 1:02.02 — 3.06 seconds and 5.19% above the record in actual competition. Ian Call (17) follows at 52.51 SCY (1:00.29 projected), with a last-season LCM reference of 1:00.49 — the most advanced real 100 breast LCM time in the group, and the tightest projection-to-reference alignment of any candidate in this event. Andrew Eubanks rounds out the group at 52.59 SCY (1:00.37 projected), with a 1:00.79 last-season LCM reference.

Call's 1:00.49 last-season LCM time is the most credible real benchmark — 1.53 seconds and 2.59% above McKean's record in actual competition, with near-perfect alignment between his projection and real reference. Despite the record's 2025 recency, Call is the name to track most closely in this event.

200 Breaststroke — NAG: 2:08.91 | Matthew Fallon (2021)

This is one of the most compelling events in the boys 17-18 dataset. Andrew Eubanks projects to 2:09.54 (+0.49%), with a last-season LCM reference of 2:12.85 — 3.94 seconds and 3.06% above Fallon's record in actual competition. Baylor Stanton follows at 2:09.83 projected (+0.71%), with a last-season LCM reference of 2:21.53 (+9.79%) — a very large real gap suggesting his long course 200 breast development is still in early stages. Collin Holgerson rounds out the group at 2:10.13 projected (+0.95%), with a last-season LCM reference of 2:21.62 (+9.86%) — essentially identical to Stanton's real baseline.

Eubanks's 2:12.85 last-season LCM time is the most credible real reference — he's been within 3.94 seconds and 3.06% of Fallon's record in actual competition. His projection of +0.49% is also the tightest among the three candidates on both measures. If he closes that real gap this summer, Fallon's 2021 record moves into genuine conversation.

Butterfly

50 Butterfly — NAG: 23.22 | Michael Andrew (2017)

Brady Campbell (17) stands out in this event. His last-season LCM reference of 23.90 (+2.93%) closely matches his projection of 23.81 (+2.54%) — tight alignment that confirms real long course sprint fly efficiency. Mattaus Rammel (18) leads on projection at 23.73 (+2.2%), but his last-season LCM reference of 25.18 (+8.44%) is considerably further back in real terms. Brandon Ha (18) rounds out the group at 24.05 projected, with a 24.37 last-season LCM reference (+4.95%) — more aligned than Rammel.

Campbell's projection-to-reference alignment is the most credible sign of genuine long course butterfly form in this event. His 23.90 last-season LCM time leads the field in real performance — 0.68 seconds above Andrew's record. That's a real gap in the 50 fly, but his conversion efficiency makes him the swimmer to watch.

100 Butterfly — NAG: 50.70 | Thomas Heilman (2025)

Set just last year at a level the current field hasn't approached. Rowan Cox (18) leads at 45.47 SCY (51.87 projected, +2.31%), with a last-season LCM reference of 52.93 — 2.23 seconds and 4.4% above Heilman's record in actual competition. Mike Rice follows at 52.34 projected, with a last-season LCM reference of 55.03 (+8.54%) — a large real gap suggesting limited long course 100 fly experience. Brandon Ha rounds out the group at 52.60 projected, with a 53.90 last-season LCM reference.

Cox's 52.93 leads the field in real competition — 2.23 seconds above a record set last year. Heilman's mark has recency protection on top of a real margin. Ha's last-season LCM reference of 53.90 is the second-most developed real baseline.

200 Butterfly — NAG: 1:53.84 | Luca Urlando (2019)

Hayden Vicknair (17) leads at 1:43.06 SCY (1:57.20 projected, +2.95%), with a last-season LCM reference of 1:59.83 — 5.99 seconds and 5.26% above the record in actual competition. Mattaus Rammel follows at 1:57.69 projected, with a last-season LCM reference of 2:06.83 (+11.41%) — a very large real gap. Brandon Ha rounds out the group at 1:57.72 projected, with a 2:01.63 last-season LCM reference (+4.08%) — the most credible real 200 fly baseline, already under 2:02.

Ha's 2:01.63 last-season LCM time is the most advanced real reference — 7.79 seconds above Urlando's record in actual competition. Vicknair leads on projection. The record has clear protection, but Ha's real performance level makes him a name to follow as the season develops.

Individual Medley

200 IM — NAG: 1:55.94 | Michael Phelps (2003)

Phelps's 200 IM is one of two records he holds in this dataset, both from 2003. Baylor Stanton projects to 1:56.00 — just 0.06 seconds and 0.05% above the record on paper. His last-season LCM reference of 2:01.46 (+4.76%) is the real measure: 5.52 seconds above the record in actual competition. The projection-to-reference gap is large — the same pattern seen in several events across this dataset where exceptional SCY form has yet to fully translate to long course. Collin Holgerson follows at 1:57.79 projected (+1.6%), with a 2:04.51 last-season LCM reference. Griffin Oehler (17) rounds out the group at 1:58.11 projected, with a 2:03.83 last-season LCM reference — the most aligned of the three between projection and real performance.

Stanton's 0.05% projection gap is the closest any swimmer gets to a standing record in the entire boys dataset. His 2:01.46 last-season LCM reference — 5.52 seconds above the record — is the honest baseline. Phelps's 2003 IM marks are comfortably protected, but Stanton's SCY level is worth watching as a long-term indicator.

400 IM — NAG: 4:09.09 | Michael Phelps (2003)

Baylor Stanton leads at 3:40.48 SCY (4:11.13 projected, +0.82%), with a last-season LCM reference of 4:19.48 — 10.39 seconds and 4.17% above Phelps's record in actual competition. Ian Heysen (18) follows at 4:14.19 projected (+2.05%) with no last-season LCM reference available. Songrui Wu (18) rounds out the group at 4:14.36 projected, with a 4:31.75 last-season LCM reference — a large real gap of 9.1%.

Stanton's 4:19.48 last-season LCM time is the most relevant real benchmark — 10.39 seconds above a mark set at a generational level in 2003. His 0.82% projection gap is tight, but the real picture reflects where this field genuinely stands. The record is protected.

Overall Picture

Baylor Stanton (18) is the defining multi-event name in the boys 17-18 dataset, appearing across backstroke, breaststroke, and both IM events. His SCY times are exceptional — projecting within 1% of two Phelps records from 2003 in the 200 and 400 IM. The recurring theme, however, is a gap between his short course form and his current long course results. His last-season LCM references in the 200 IM (4.76% above the record) and 200 breast (9.79%) are significantly larger than the projection gaps suggest. The 200 breast (+0.71% projection, +9.79% reference) illustrates that gap most starkly. The 400 IM (+0.82% projection, +4.17% reference) is the event where his projection and real performance are most closely aligned — and the more credible watch of the two.

Collin Holgerson (18) appears across five events and carries the most consistent real long course profile in the dataset. His last-season LCM references in the 50 back (25.64), 200 back (1:59.45), and 100 breast (1:02.02) lead the field in those events on real performance. He doesn't project as close to records as Stanton, but his conversion efficiency is more established.

Ian Call (17) is the most compelling single-event story in real terms: his last-season LCM reference of 1:00.49 in the 100 breast is the tightest projection-to-reference alignment in the dataset, and puts him within 1.53 seconds of McKean's 2025 record in actual competition. Andrew Eubanks leads the 200 breast picture with the most credible real long course breaststroke form, and Mike Rice in the 100 free — already sub-50 LCM last summer — is the most developed real sprint free reference in the field.

All projections use classical SCY-to-LCM conversion. Converted times are estimates only. Backstroke projections in particular can run aggressive with classical conversion — last-season LCM references are the more reliable indicator in those events. Last-season LCM reference times are from the 2024–25 season. Age eligibility based on August 1, 2026 cutoff (swimmer remains 17 or 18 as of 8/1/2026).