Swimrun Pace Calculator
Enter your swim and run paces, select a race profile (or enter custom distances), and get an estimated finish time with adjustments for shoe drag, trail terrain, and transition time between sections.
Your pool or open-water pace without shoes
Your road running pace
How the Calculator Works
The calculator applies two key adjustments to your input paces:
- Shoe drag (+12s/100m swim): Swimming in trail shoes creates significant water resistance, slowing your swim pace. Hand paddles offset some of this drag, but most athletes still lose 10-15 seconds per 100m. The calculator uses +12s as a conservative average.
- Trail penalty (+18% run): Swimrun courses use natural terrain — rocky coastlines, forest trails, wet roots — not paved roads. The 18% penalty represents a moderate trail course. Flat coastal courses may only add 10%, while steep mountain terrain can add 25%+.
- Transition tax (~30s each): Each water entry/exit costs approximately 30 seconds for the physical transition and movement pattern switch. An ÖTILLÖ race with 52 transitions adds ~26 minutes in total transition time.
Race Profile Guide
The calculator includes presets for major race series. Distances are approximate — actual course measurements vary year to year:
- ÖTILLÖ Sprint: ~7.5km (1.5km swim + 6km run), 8 sections
- ÖTILLÖ Short: ~12.5km (2.5km swim + 10km run), 12 sections
- ÖTILLÖ Medium: ~22km (4km swim + 18km run), 16 sections
- ÖTILLÖ Long: ~42km (7km swim + 35km run), 24 sections
- ÖTILLÖ World Championship: ~75km (10km swim + 65km run), 52 sections
- My Swimrun Short/Medium: 10-19.5km, 10-14 sections
- Mudskipper Short/Long: 8.5-18km, 8-14 sections
For races not listed, use the Custom profile and enter the swim distance, run distance, and number of sections from the race information page.
Using Your Results
- Nutrition planning: For estimated race times over 2 hours, plan 200-300 calories per hour stored in wetsuit pockets
- Pacing strategy: Start conservatively — the transition tax accumulates faster than you expect
- Training targets: Train at your adjusted pace (with shoe drag and trail penalty) not your pool/road pace
- Partner alignment: Both team members should run the calculator with their individual paces — the slower result is your team target
Frequently Asked Questions
How accurate is the swimrun pace calculator?
The calculator provides estimates based on your input paces with standard adjustments for shoe drag (+12s/100m) and trail terrain (+18%). Actual race times vary based on course difficulty, water conditions, weather, and fatigue. Use the results as a planning baseline, not a guarantee.
What is shoe drag in swimrun?
Swimming in trail shoes adds significant water resistance, typically slowing your pace by 10-15 seconds per 100m compared to barefoot or wetsuit-only swimming. The calculator uses a +12s/100m adjustment as the average. Hand paddles can recover 5-8 seconds of this.
What is the transition tax?
Each transition between swimming and running costs approximately 30 seconds — exiting the water, adjusting gear, and switching your movement pattern. A long ÖTILLÖ race with 52 transitions adds ~26 minutes to your race time. The calculator accounts for this automatically.
Should I use my pool pace or open-water pace?
Use your open-water pace if you have one — it's more realistic than pool pace for race conditions. If you only have pool times, your open-water pace is typically 5-10% slower. The calculator's shoe drag adjustment is on top of whichever pace you enter.
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