How to Track Laps for a 500m Swim | Stop Losing Count

Whether 500 meters adds up to 10 or 20 lengths depends entirely on your pool, and the word “lap” makes things worse because swimmers use it two different ways. In US swim coaching, one pool crossing is a “length,” while a “lap” usually means a down-and-back trip. That single distinction changes your count, which is why every guide worth reading starts with the same advice: define your terms before you touch the water.

How Many Lengths Is 500m, By Pool Size?

Your count is set by one number: how long the pool is. A 25-meter pool is the standard short-course size, and a 50-meter pool is the Olympic length.

• 25m pool: 500m is 20 lengths. If you count “laps” as out-and-back trips, that’s 10 laps.
• 50m pool: 500m is 10 lengths, or 5 round-trip laps.
• 25-yard pool: This is the trap. A yard is shorter than a meter, so 500m doesn’t divide evenly into 25-yard lengths. Since many US pools are yard-based, you’ll need to convert or swim a set distance instead of an exact 500m.

Low-Tech Counting That Actually Works

Mental counting falls apart by lap ten, so swimmers use tricks that free up their brain. The most reliable low-tech options come straight from swim coaching practice:

• Start at zero and count wall touches. Tap or click your counter once at each completed length, and stop at 20 in a 25m pool.
• Use a wrist tally band. Flip one bead or band per length, then start over at ten.
• Move a lane buoy. Push a lane-divider buoy one position along the line after each length. You can’t lose count if the marker sits right at your turn.
• Break the swim into sets. Instead of one continuous 500m count, swim 5×100m segments and count each one separately. The math stays easy, and you get natural rest breaks.

If you have a poolside helper, place the counter where you can see it on approach, not where you’re looking away from your turn. For long events, YMCA guidance suggests switching to a red indicator on the last few lengths so the swimmer knows the finish is close.

Watches, Counters, And Digital Tracking

Devices remove the mental work entirely, but only if you set them up right. A Garmin-style swim watch requires you to select Pool Swim mode and enter the pool length before you start; otherwise the distance and lap totals will be wrong. The watch relies on detecting your turns, so it needs the correct pool size to compute anything useful.

Online counters like Digital Tally Counter or SimpleCounter work by tapping once per length, and the LapBuddy app does the same on an iPhone. The catch for phone-based counters is water safety: place the phone at the lane end on a dry, stable surface, never near splash zone.

Whichever method you pick, the rule is the same: know the total count before you push off the wall.

Before you invest in gear, compare what the fitness trackers offer for pool-swim tracking, including which models handle pool-length entry and turn detection reliably. Our tested exercise tracker for swimming roundup breaks down the waterproof options that actually compute laps correctly.

Common Mistakes That Break Your Count

The biggest error is confusing “lap” with “length.” Multiple swim sources use the terms differently, so if you don’t define yours first, your 500m target quietly becomes a different distance. The second error is ignoring pool size entirely and assuming the count transfers between pools. The third is trying to hold a mental tally across one long continuous swim, which is exactly why set-based counting and devices exist.

For phone-based counters, keep the device at the lane end, away from water, and check that it’s visible at your turn. Watch-based tracking only works when the swimmer enters the correct pool length; turn-detection varies by model, so current specs should be confirmed on the manufacturer’s page before buying.