| Event | Time | Meet | Date |
|---|---|---|---|
| 100m Butterfly | 1:09.10 | Victoria Masters Swim Club Long Course Meet | 2026-01-24 |
| 100m Freestyle | 59.60 | 2025 Winskill Otters' Ottermania LC | 2025-11-01 |
| 100m Freestyle | 59.89 | North Shore Masters Sprint Meet | 2025-10-18 |
| 200m Freestyle | 2:19.26 | Victoria Masters Swim Club Long Course Meet | 2026-01-24 |
| 50m Butterfly | 27.50 | 2025 Winskill Otters' Ottermania LC | 2025-11-01 |
| 50m Butterfly | 28.48 | North Shore Masters Sprint Meet | 2025-10-18 |
| 50m Freestyle | 27.22 | North Shore Masters Sprint Meet | 2025-10-18 |
Johnston, Sam's top personal bests include 100m Butterfly (1:09.10), 100m Freestyle (59.60), 100m Freestyle (59.89), 200m Freestyle (2:19.26), 50m Butterfly (27.50).
Johnston, Sam swims for Winskill Otters Masters Swim Club.
Johnston, Sam has competed in 3 meets.