Wear your goggles over the cap for everyday training, and under the cap when you dive in, race or swim hard sets with lots of tumble turns. Over the cap is quicker to adjust and easier to push up between sets. Under the cap, the cap edge pins the strap to your head, so a dive entry or a big push-off is much less likely to drag your goggles off your eyes.
That split is a common default rather than a rule, and some swimmers happily do the opposite. What matters in both orders is that the strap sits low on the back of your head and stays there. Below: a side-by-side comparison, a setup routine for each order, a quick test for today's session, and fixes for a strap that keeps creeping.
Over or under the cap: the side-by-side
| Goggles over the cap | Goggles under the cap | |
|---|---|---|
| Adjusting mid-session | Easy: reach back and slide the strap | Awkward: you have to lift the cap edge |
| Dives and fast turns | Fine if the strap sits low, but the weaker of the two | More secure: the cap holds the strap flat |
| Pressure on your head | Strap only | Strap and cap edge press on the same line |
| Hair | Strap sits on the cap | Strap sits on your hair and can tug on the way off |
| Best for | Easy laps, drills, beginners, kids | Dive starts, racing, hard turn sets, open water |
Why goggles under the cap hold better
When you dive in, the water hits the front of your goggles hard and tries to peel them down your face. A strap sitting on top of a smooth silicone cap has only friction to hold it. A strap under the cap is held from both sides: your head underneath, the cap edge on top. A hard push-off or a fast flip turn does the same thing on a smaller scale.
The price is convenience. Once the cap is on, adjusting the strap means peeling the cap edge back, and the strap sits directly on your hair.
Why over the cap is the easy default for training
Training involves a lot of fiddling. You push the goggles up to read the board, rinse a foggy lens, loosen the strap after the main set. With the strap on the outside, all of that takes two seconds and the cap stays where you put it. It's also the easier order for beginners and children, because they only have to get one layer right at a time.
The weak point is the smooth surface. A strap that sits high on the crown of a silicone cap slides upwards every time you push off, so the fix is position rather than tension. Keep the strap low, on or just below the bony bump at the back of your skull. With a split strap, spread the two bands so one sits above the bump and one below it.
How to set up each order
Goggles under the cap
- Set the strap length on dry land. Do it in the changing room. Adjusting a strap under a wet cap on the pool deck is a comedy routine your lane does not need to watch.
- Goggles on first. Press the eyecups in until they seal, then sit the strap low on the back of your head.
- Cap on over the top. Use the two-hand stretch from our guide on how to put on a swim cap without the struggle, starting at the front hairline and pulling back and down.
- Cover the strap. Run a finger round the edge so the cap sits over the strap at the back and sides.
- Keep the cap off the seals. At the front, the cap edge belongs just above the goggle frame. Silicone resting on the eye seals can lift them and let water in.
Goggles over the cap
- Cap on first, front edge at your hairline, ears in or out as you prefer.
- Smooth the back. Press out any wrinkles where the strap will sit. A fold in the silicone works like a ramp for the strap.
- Goggles on, eyecups sealed, strap low on the back of the cap rather than on the crown.
- Snug, not tight. Tighten until the goggles stay put when you shake your head, then stop. The seal comes from the eyecups, not from squeezing your skull.
The push-off test: which order does today's session need?
Rather than guessing, test it in the first 200 metres of warm-up: one hard streamline push-off from each wall, two or three tumble turns at speed, and one dive start if your pool and coach allow it.
If the goggles stay put, your order and strap position are fine for that session. If they shift, lower the strap before you change anything else. If they still move on the dive, switch to goggles under the cap. And if you finish warm-up with a headache or deep red rings round your eyes, the setup is too tight, whichever order you chose.
Common mistakes and quick fixes
- Strap on the crown. It slides up the silicone on every push-off. Move it lower.
- Cranking the strap to stop leaks. Leaks usually come from how the eyecups sit on your face, not from a loose strap. Over-tightening buys you sore eyes and a headache instead of a seal.
- A baggy or stretched cap. If the cap itself creeps up during a set, the strap has nothing firm to sit on in either order, and goggles on top won't hold a cap that's too big. Work through our checklist for a swim cap that keeps slipping before you blame the goggles.
- Goggles off before the cap. With the strap under the cap, pulling the goggles off first drags the strap through your hair. Take the cap off first, using the peel-from-the-back method in how to take off a swim cap, then the goggles.
Long hair, kids, open water and headaches
- Long hair. Whichever order you use, the strap goes below the bun. Above it, the strap has nothing to hold on to and rides up and off. With braids, curls or a lot of hair, the cap has less room for a strap underneath, so many swimmers go over the cap. More in our guide to choosing a swim cap for long hair.
- Kids. Over the cap is easier for children to manage and fix themselves mid-lesson. Teach them to keep the strap low; under the cap can wait until they're diving in at galas.
- Open water and triathlon. On race day the organisers' coloured cap goes on top, and many swimmers put their goggles under it, often with their own cap underneath too. Mass starts involve a lot of stray arms and feet, and a covered strap copes better. Our guide to the best swim cap for open water swimming covers visibility and cold water.
- Pressure headaches. Goggles under the cap stack two layers of pressure on the same line. If you get headaches, try goggles over the cap with the strap a notch looser. Our guide on why a swim cap can give you a headache has more fixes, and headaches that carry on after you've changed the fit are worth mentioning to a doctor.
Race day: the double-cap option
There's a third order, and you'll see it behind the blocks at plenty of galas: first cap, then goggles, then a second cap over the top. The strap ends up sandwiched between two layers, which is about as secure as goggles get. It's also the fussiest setup, so most swimmers save it for racing. The full routine, the best cap pairings and the mistakes to avoid are in our guide to why swimmers wear two caps.
What the order won't fix
Goggle order changes security and comfort, not the seal or the view. Fogging is a lens problem: anti-fog treatment helps, and so does keeping your fingers off the inside of the lenses. Water in the goggles comes from eyecups that don't suit your face or aren't pressed in properly. No cap seals your goggles for you.
If your cap has gone baggy and the strap slides whatever you do, the cap may simply be worn out: our guide on how often to replace a swim cap lists the signs. And if you'd like the replacement to have a bit of personality, the CutWave silicone cap range is a good place to start.
Related guide: centre the cap before adding goggles
Related guide: what to bring to swimming lessons
Related guide: cap and goggles order in T1
Related guide: goggles and caps in artistic swimming
FAQ
Why do my goggles come off when I dive in?
Usually it's a mix of strap position and head position. Keep the strap low on the back of your head, tighten it slightly for racing, and tuck your chin so you enter the water with your head between your arms rather than looking forward. Lifting your head on entry lets the water hit the lenses head-on. If they still shift, wear them under the cap or between two caps.
How tight should a goggle strap be?
Snug enough that the goggles stay put when you shake your head, loose enough that they don't leave deep marks after a session. A quick fit check: press the goggles onto your eyes without the strap. If they hold for a moment by suction, the eyecups suit your face and the strap only needs to keep them in place.
Do split-strap goggles work better on top of a cap?
Many swimmers find them steadier over a cap, because the two bands spread across the back of the head instead of balancing on one line. Place one band above the bump at the back of your skull and one below it. They work under the cap too, as long as both bands are covered.
Is it bad to wear goggles under the cap every session?
No. It suits swimmers who do a lot of dive starts or fast turns. The trade-offs are that mid-session adjustments take longer and the strap sits on your hair, so take the cap off before the goggles at the end of the session.