Brick Session Calculator

Brick Session Calculator — calculate brick session for training and performance. Evidence-based formula and benchmarks.

A swimming calculator computes pace per 100 metres or yards, training zones, swim efficiency (SWOLF score), and projected race times across pool and open water distances. Swimming pace analysis is more complex than running because pool length (25m, 25yd, or 50m), stroke type, and turn efficiency all significantly affect split times. SWOLF (strokes + time for 25m) is a key efficiency metric — lower is better.

Used by competitive swimmers, triathletes planning swim splits, masters swimmers setting training targets, and coaches designing interval sets.

Enter your time for a known distance (e.g. 1:45 for 100m) to calculate pace per 100m or 100yd.
Use the distance converter to compare pool (SCM/SCY/LCM) and open water times — open water is typically 3–8% slower than pool pace due to navigation and sighting.
Calculate SWOLF by entering your stroke count per length and time per length — aim to reduce SWOLF by improving technique before increasing training volume.
For triathlon planning, enter your target 1500m or 1900m swim time to calculate required pace per 100m.

Swimming pace and efficiency formulas

Pace per 100m = (Race time in seconds / Distance in metres) × 100

SWOLF = Stroke count per length + Time (seconds) per length — measures efficiency (lower = more efficient)

Pool conversion (SCY to LCM): LCM time ≈ SCY time × 1.11 (rule of thumb; varies by swimmer)

CSS (Critical Swim Speed) = (distance2 − distance1) / (time2 − time1) — anaerobic threshold pace estimated from two timed swims

Interpreting swimming pace results

Pace benchmarks by ability level

Recreational: 2:30+ per 100m. Intermediate: 1:45–2:30. Competitive masters: 1:15–1:45. Elite age-group: 1:05–1:20. National-level: 0:55–1:05. Olympic-standard freestyle: 0:48–0:56 per 100m LCM. For triathlon, an Ironman swim of 1:00–1:10 per 100m sustained for 3.86 km (2.4 miles) is a competitive performance; completing within the cut-off (~2:20) requires only ~3:30/100m.

Sports tips and best practices

Bilateral breathing (every 3 strokes) promotes a balanced stroke and is worth practising even if you race breathing to one side.
Streamline off every wall — a good underwater dolphin kick (2–3 kicks) after each turn can save 0.5–1.0 seconds per length in a 50m pool.
CSS training (critical swim speed intervals) is the most efficient way to improve open water and triathlon swim pace.
Wetsuit in open water adds approximately 3–5% speed benefit due to buoyancy — account for this when predicting open water times from pool tests.

The world record 100m freestyle (men, LCM) is 46.40 seconds (César Cielo, 2009) — a pace of 46.4 seconds per 100m, equivalent to 13.4 mph or 21.6 km/h.
Olympic 1500m freestyle (men) world record: 14:31.02 (Bobby Finke, 2021) — sustained pace of ~58.1 sec/100m for 15 lengths.
A typical Ironman swim (3.86 km) winner swims in approximately 45–50 minutes (~70–77 sec/100m pace), while the median finisher takes 1:10–1:20.

Common mistakes to avoid

Not accounting for pool type when comparing times — short-course yards (SCY) times are fastest due to more turns; long-course metres (LCM) are slowest.
Setting open water race targets from pool times without a correction factor — open water sighting, currents, and mass-start navigation add time.
Focusing on volume over technique — in swimming, technique improvements (stroke mechanics, turns, starts) produce larger speed gains than volume alone, especially for recreational and intermediate swimmers.

Swimming involves risk — always swim in a supervised environment with a qualified lifeguard present. Open water swimming carries additional risks from currents, cold water, and visibility. Seek qualified coaching before competitive training. Time predictions are estimates only.