swimMason Kostov
Personal records
| Event | Course | Best | Cut | Date | Meet |
|---|---|---|---|---|---|
| 25 Freestyle | SCY | 16.18 | 2019-11-16 | 2019 MR LIAC A Saturday in November | |
| 50 Freestyle | SCY | 21.74 | AAA+0.05s to AAAA·Sectionals ✓+0.45s to Futures | 2025-03-14 | 2025 MR SC Junior Metropolitan Championships |
| 100 Freestyle | SCY | 48.98 | AAA+1.49s to AAAA·+0.49s to Sectionals | 2025-12-14 | 2025 Katie Ledecky Invitationalvenue |
| 200 Freestyle | SCY | 1:40.80 | AAAA·Futures ✓+2.41s to Winter JNs | 2025-02-13 | 2025 MR TYR Senior Met Winter Championship |
| 500 Freestyle | SCY | 5:05.60 | AA+9.91s to AAA·+18.21s to Sectionals | 2025-10-24 | 2025 MR AGUA October Time Trials |
| 25 Backstroke | SCY | 39.69 | 2019-11-16 | 2019 MR LIAC A Saturday in November | |
| 50 Backstroke | SCY | 31.48 | B+1.19s to BB·+7.79s to Futures | 2022-03-11 | 2022 MR Metro SC Junior Olympics |
| 100 Backstroke | SCY | 1:00.48 | BB+0.89s to A·+5.99s to Sectionals | 2024-02-09 | 2024 MR LIE Second Chance Meet |
| 200 Backstroke | SCY | 2:15.05 | BB+4.96s to A·+16.46s to Sectionals | 2024-02-09 | 2024 MR LIE Second Chance Meet |
| 50 Breaststroke | SCY | 37.01 | B+2.22s to BB·+10.72s to Futures | 2022-02-26 | 2022 MR Metro Silver Championship Central |
| 100 Breaststroke | SCY | 1:05.40 | A+0.81s to AA·+3.91s to Sectionals | 2024-03-28 | 2024 Eastern Zone SC Age Group Championshipsvenue |
| 25 Butterfly | SCY | 19.50 | 2019-11-16 | 2019 MR LIAC A Saturday in November | |
| 50 Butterfly | SCY | 25.54 | AA+0.15s to AAA·+2.65s to Futures | 2026-03-29 | 2026 EZ North Speedo Short Course Sectionalsvenue |
| 100 Butterfly | SCY | 58.30 | A+1.91s to AA·+5.11s to Sectionals | 2024-11-08 | 2024 MR LIE Fall Classic Invitational |
| 200 Butterfly | SCY | 2:17.35 | BB+5.36s to A·+16.16s to Sectionals | 2026-01-19 | 2026 MR AGUA MLK Invitationalvenue |
| 100 Individual Medley | SCY | 58.46 | 2025-10-11 | 2025 MR AGUA Season Starter Invitationalvenue | |
| 200 Individual Medley | SCY | 2:07.00 | A+0.31s to AA·+7.61s to Sectionals | 2024-03-29 | 2024 Eastern Zone SC Age Group Championshipsvenue |
| 50 Freestyle | SCM | 25.93 | AA+0.84s to AAA·+1.24s to Sectionals | 2023-05-07 | 2023 MR FREE Freedom Meters Showdownvenue |
| 100 Freestyle | SCM | 57.92 | A+0.43s to AA·+4.03s to Sectionals | 2023-06-04 | 2023 MR FREE SCM Summer Splash Invitevenue |
| 100 Backstroke | SCM | 1:09.67 | BB+3.88s to A·+9.68s to Sectionals | 2023-06-04 | 2023 MR FREE SCM Summer Splash Invitevenue |
| 50 Breaststroke | SCM | 34.92 | A+0.93s to AA | 2023-05-06 | 2023 MR FREE Freedom Meters Showdownvenue |
| 100 Breaststroke | SCM | 1:15.22 | BB+0.83s to A·+6.23s to Sectionals | 2023-05-07 | 2023 MR FREE Freedom Meters Showdownvenue |
| 50 Butterfly | SCM | 29.33 | AA+1.24s to AAA | 2023-06-04 | 2023 MR FREE SCM Summer Splash Invitevenue |
| 100 Individual Medley | SCM | 1:08.04 | 2023-05-06 | 2023 MR FREE Freedom Meters Showdownvenue | |
| 200 Individual Medley | SCM | 2:27.46 | BB+1.37s to A·+14.87s to Sectionals | 2023-05-07 | 2023 MR FREE Freedom Meters Showdownvenue |
| 50 Freestyle | LCM | 25.19 | AAA+0.20s to AAAA·Sectionals ✓+0.60s to Futures | 2024-07-31 | 2024 ISCA Summer Senior Blastvenue |
| 100 Freestyle | LCM | 55.77 | AAA+1.28s to AAAA·+0.28s to Sectionals | 2025-08-08 | 2025 Summer Elite Showcasevenue |
| 200 Freestyle | LCM | 2:08.22 | AA+2.43s to AAA·+6.93s to Sectionals | 2025-08-09 | 2025 Summer Elite Showcasevenue |
| 400 Freestyle | LCM | 4:47.96 | A+8.07s to AA·+30.37s to Sectionals | 2024-06-22 | 2024 MR LIE June Jamboree Invitationalvenue |
| 50 Backstroke | LCM | 31.71 | AA+1.32s to AAA·+3.82s to Futures | 2025-08-06 | 2025 Summer Elite Showcasevenue |
| 100 Backstroke | LCM | 1:09.77 | BB+0.18s to A·+7.78s to Sectionals | 2024-06-22 | 2024 MR LIE June Jamboree Invitationalvenue |
| 200 Backstroke | LCM | 2:37.52 | BB+6.43s to A·+22.73s to Sectionals | 2024-05-26 | 2024 MR AGUA Memorial Day Invitationalvenue |
| 50 Breaststroke | LCM | 33.84 | AA+0.35s to AAA·+2.95s to Futures | 2024-08-01 | 2024 ISCA Summer Senior Blastvenue |
| 100 Breaststroke | LCM | 1:15.39 | A+0.30s to AA·+5.70s to Sectionals | 2024-01-01 | 2024 nbac mid summer classic final results pdf |
| 200 Breaststroke | LCM | 2:51.61 | BB+0.22s to A·+19.02s to Sectionals | 2024-07-31 | 2024 ISCA Summer Senior Blastvenue |
| 50 Butterfly | LCM | 28.31 | AAA+0.92s to AAAA·+2.02s to Futures | 2025-08-09 | 2025 Summer Elite Showcasevenue |
| 100 Butterfly | LCM | 1:06.15 | A+1.66s to AA·+5.96s to Sectionals | 2024-06-22 | 2024 MR LIE June Jamboree Invitationalvenue |
| 200 Individual Medley | LCM | 2:22.69 | AA+2.20s to AAA·+6.50s to Sectionals | 2024-07-31 | 2024 Summer Elite Showcase |
| 400 Individual Medley | LCM | 5:28.59 | A+13.00s to AA·+38.70s to Sectionals | 2024-06-23 | 2024 MR LIE June Jamboree Invitationalvenue |
Cuts are USA Swimming single-age motivational standards (B → AAAA) at age 15.
National cuts (Sectionals → Nationals) are the current-season meet qualifying times for the swimmer's zone and age group; ✓ marks the hardest cut already achieved.
Fastest relay legs
| Leg | Course | Time | Start | Relay | Date | Meet |
|---|---|---|---|---|---|---|
| 50 Freestyle | SCY | 21.96 | flat | 200 Free Relay | 2026-02-13 | 2026 MR TYR Senior Mets Winter Championship |
| 50 Freestyle | SCY | 22.40 | flying | 200 Free Relay (leg 4) | 2024-03-29 | 2024 Eastern Zone SC Age Group Championships |
| 50 Freestyle | SCY | 23.62 | flying | 200 Medley Relay (leg 4) | 2024-03-30 | 2024 Eastern Zone SC Age Group Championships |
| 100 Freestyle | SCY | 49.58 | flying | 400 Medley Relay (leg 4) | 2025-12-13 | 2025 Katie Ledecky Invitational |
| 100 Freestyle | SCY | 50.06 | flying | 400 Free Relay (leg 3) | 2024-03-27 | 2024 Eastern Zone SC Age Group Championships |
| 50 Breaststroke | SCY | 29.18 | flying | 200 Medley Relay (leg 2) | 2025-12-12 | 2025 Katie Ledecky Invitational |
| 50 Freestyle | LCM | 25.16 | flat | 200 Free Relay | 2024-07-12 | 2024 MR Senior Mets LC Summer Championship |
| 50 Freestyle | LCM | 25.26 | flying | 200 Medley Relay (leg 4) | 2024-07-19 | 2024 Metropolitan LC Junior Met Championships |
| 100 Freestyle | LCM | 56.63 | flying | 400 Medley Relay (leg 4) | 2024-07-21 | 2024 Metropolitan LC Junior Met Championships |
| 100 Freestyle | LCM | 56.66 | flying | 400 Free Relay (leg 2) | 2024-07-20 | 2024 Metropolitan LC Junior Met Championships |
Reconstructed from relay split marks. Flat = lead-off (comparable to individual times); flying starts run ~0.5–0.7s fast and are not PRs.
IMX / IMR
IMX 15-16 · LCM
3242 points (5/6 events — incomplete)
| Event | Time | Points |
|---|---|---|
| 400 FR LCM | 4:47.96 | 659 |
| 200 BK LCM | 2:37.52 | 551 |
| 200 BR LCM | 2:51.61 | 614 |
| 200 IM LCM | 2:22.69 | 793 |
| 400 IM LCM | 5:28.59 | 625 |
| 200 FL LCM | — | 0 |
IMR 15-16 · SCY
3661 points (5/5 events)
| Event | Time | Points |
|---|---|---|
| 200 FR SCY | 1:40.80 | 1035 |
| 100 BK SCY | 1:00.48 | 588 |
| 100 BR SCY | 1:05.40 | 686 |
| 100 FL SCY | 58.30 | 645 |
| 200 IM SCY | 2:07.00 | 707 |
Scored against AAAA motivational base times: ordering is exact, absolute points run ~25% above the official USA Swimming scale.
PR splits
100 Freestyle SCY 48.98
Front half 23.65s · back half 25.33s
200 Freestyle SCY 1:40.80
500 Freestyle SCY 5:05.60 split/total mismatch
100 Backstroke SCY 1:00.48
100 Breaststroke SCY 1:05.40
Front half 30.36s · back half 35.04s
25 Butterfly SCY 19.50 split/total mismatch
Front half 90.39s · back half -70.89s
100 Butterfly SCY 58.30
Front half 26.91s · back half 31.39s
200 Butterfly SCY 2:17.35
Front half 63.50s · back half 73.85s
100 Individual Medley SCY 58.46
Front half 27.93s · back half 30.53s
200 Individual Medley SCY 2:07.00
Front half 61.70s · back half 65.30s
100 Freestyle SCM 57.92
Front half 28.05s · back half 29.87s
100 Backstroke SCM 1:09.67
Front half 34.33s · back half 35.34s
200 Freestyle LCM 2:08.22
Front half 60.64s · back half 67.58s
400 Freestyle LCM 4:47.96
Front half 140.45s · back half 147.51s
200 Backstroke LCM 2:37.52
Front half 75.40s · back half 82.12s
100 Breaststroke LCM 1:15.39
Front half 34.56s · back half 40.83s
200 Breaststroke LCM 2:51.61
Front half 80.26s · back half 91.35s
400 Individual Medley LCM 5:28.59
Front half 160.51s · back half 168.08s
Reaction time
From electronically-timed starts only (~2% of corpus swims carry a reaction time). PRs with a recorded reaction show an RT chip in the splits section above.
Swim history
Every recorded swim, newest first
| Date | Event | Course | Time | Age | Round | Meet |
|---|
Individual swims with a recorded date and time — including disqualifications — plus reconstructed relay legs (marked). Assembled in the browser from this page’s data.
Progression
Faster times are higher. One card per event, all courses & history.