Pace per 100: The time to swim 100 yards or meters at the average pace needed to hit your target. This is the number coaches post on the workout board for interval send-off times.
Even Splits: Every lap takes the same time — the simplest pacing strategy and a good baseline for training sets.
Negative Splits: The second half of laps are about 1% faster than the first. This back-half acceleration mirrors how many competitive swimmers race middle-distance events.
Positive Splits: The first half is 1% faster. Common when fatigue sets in, but sometimes used deliberately in short races where an aggressive start matters.
Cumulative Column: Shows your running total time after each lap so you can check the pace clock mid-set and know if you are ahead or behind target.
How This Calculator Works
You set a pool unit (yards or meters), pool length (25 or 50), target distance, target time, and a pacing strategy. The tool calculates the number of laps (distance ÷ pool length, rounded up), divides total time evenly across laps for even splits, or adjusts the first and second halves by ±1% for negative and positive strategies. All three strategies sum to the same total target time.
Quick Questions
Should I use a 25-yard or 50-meter pool setting?
Match the setting to the pool you will be swimming in. Most U.S. fitness centers have 25-yard pools. Olympic and many competitive pools are 50 meters. The number of laps and turns differs significantly between the two.
Why is the 1% split difference smaller than for running splits?
Swimming pacing tends to be tighter than running because water resistance penalizes speed changes more sharply. A 1% shift per half is typical for competitive swim pacing; larger swings waste energy fighting drag.
Do turns and push-offs affect my actual split times?
Yes. In a 25-yard pool you turn twice as often as in a 50-meter pool. Good turns can save 0.5–1 second per lap. If your turns are weak, your actual splits may be slightly slower than the table suggests.
Can I use this for open-water swims?
The splits table assumes a pool with consistent lap lengths. In open water there are no walls or turns, and currents, waves, and sighting affect pace. You can still use the pace-per-100 number as a rough guide, but the lap schedule will not directly apply.