Skate Sharpening & the Radius of Hollow
Experimenting with skate sharpening can help you find your edge. When the shop asks “how do you want your skates sharpened or what hollow do you want?” they're asking how deep a groove to cut into the bottom of your blades. That one number changes how your skates stop, turn, and glide, and it has a big impact on how you feel on the ice. The Rink Hunters Hollow Finder below shows you what the radius of hollow actually looks like, so you can pick the hollow that works best for you. For example, a skater whose edges keep catching mid-stop — biting into the ice instead of shaving across it — often finds a 5/8″ hollow easier to stop on than a 1/2″. Move the slider below and watch it happen.
The Hollow Finder
Your blade, end-on · a 3 mm hockey runner · depth shown 6× actualWhere the number comes from. Your sharpener dresses this exact radius into the edge of the grinding wheel, then runs your blade along it. Even a 5/8 inch arc is large next to a 3 mm blade — the blade only ever rides the very top of it, which is why the groove ends up just thousandths of an inch deep. Shrink the circle and that top gets curvier fast.
What sharpening actually does
A skate blade doesn't get sharpened to a point like a knife. It gets a groove cut down the middle of its flat bottom. What's left on either side of that groove are two corners — your inside edge and outside edge. Those two thin lines of steel are the only part of the skate that ever touches the ice.
The radius of hollow (ROH) describes the shape of that groove. It's the radius of the circle the groove follows. A 5/8″ sharpening means the bottom of your blade now matches an arc from a circle 5/8 of an inch in radius. Smaller radius, tighter arc, deeper groove, more aggressive edges. Bigger radius, flatter arc, shallower groove, freer glide.
The part nobody believes: a 1/2″ hollow on a 3 mm blade is about 3.5 thousandths of an inch deep — roughly a sheet of copy paper. The whole difference between a 1/2″ and a 1″ sharpening is less than the thickness of a human hair, and skaters can feel it on the first stride.
Why so sensitive? Because the edge angle changes with it. A deeper groove tilts the corner of the steel into a more acute angle, so it slices into the ice with less effort. It also means the edge sinks deeper before the blade finds support — more grip on a hard stop, and more drag on every glide you take in between.
Bite and glide are the same trade
There's no “best” hollow, only a trade you get to pick. Every bit of grip you add on stops and tight turns is speed you give up on straightaways, and every bit of glide you gain is grip you'll miss when you need to change direction in a hurry. Where you want to sit on that line depends on your weight, your skating, your position, and the ice you play on.
Every common hollow, side by side
Depths and angles below are calculated for a 3 mm (0.118 in) hockey runner. Tap any row to load it into the blade above.
| Hollow | Metric | Depth | Edge angle | Character | What it feels like |
|---|
Depth and edge angle are geometry — they're exact for a 3 mm blade. The character and feel columns are not: they describe the trade each cut makes, not who should skate it. There's no rule matching a hollow to a position, a size, or a skill level — forwards, defensemen, and goalies all turn up at every one of these numbers. Use how to choose your hollow below, then trust your own feet.
How to choose your hollow
If you genuinely don't know what your skates are cut at right now, you can start here: 5/8″ for adult recreational hockey, 1/2″ for youth players. Those are the two most common defaults in North American shops, and both are a fair middle. Then adjust using what actually happens on the ice.
Your weight
Heavier skaters press the edge into the ice harder, so the same hollow bites more. Bigger players usually end up shallower (a larger number); lighter and younger skaters usually need deeper to find grip.
Your skating
Stops tell you the most. If you're slipping out and can't hold an edge, go deeper. If your edges grab and won't release mid-stop — or your legs burn on long strides — go shallower.
Your ice
Cold, hard arena ice resists the edge, so the same cut feels duller — many players go a step deeper in mid-winter. Warm, soft rec-rink ice lets the edge sink in, so a shallower cut feels better.
Your position
Defensemen who pivot and gap up often like a bit more bite; forwards chasing speed often like less. Goalies vary more than anyone — some go shallow so slides release cleanly, and plenty skate 1/2″ or 5/8″ like everybody else.
Rules of thumb that actually help
- Change one step at a time. 5/8″ to 3/4″, not 5/8″ to 1″. A single step is a real, noticeable difference.
- Give it two or three skates. Any change feels wrong for the first fifteen minutes. Judge it once you've stopped thinking about your feet.
- Write your number down. Keep it in your phone. Shops ask every time, and “whatever you did last time” doesn't survive a change of staff.
- Same shop, same machine, when you can. Two shops can both hand you a “5/8″” that feels different — wheel condition, dressing, operator technique, and how much steel gets taken all show up in the result.
- Don't chase someone else's number. Pro players' hollows get passed around like gospel, and they run the whole range from deep to nearly flat. Copy the reasoning, not the number.
Myths, and the other cuts you'll hear about
“Hollow” is not “profile”
The most common mix-up in the shop. The hollow is the groove across the width of the blade — the thing this whole page is about. The profile (or rocker) is the curve along the length of the blade, which decides how much steel is on the ice at once and how the skate pivots. They're different measurements, done on different machines, and they both get quoted in inches, which is how everyone ends up confused.
“Sharper” doesn't mean deeper
A clean 1″ hollow with crisp, even edges is sharper than a beat-up 1/2″ with a rolled edge. Sharp is about edge quality; hollow is about edge shape. If your skates feel bad right after a sharpening, the problem is usually a bad grind or uneven edges, not the number.
Flat Bottom V and other cuts
A few shops offer alternatives to the standard round hollow. The best known is Flat Bottom V (FBV), from Blackstone, which leaves a flat strip in the middle with a small V-groove edge on each side — the pitch is more bite and more glide, and it's quoted with two numbers (like 100/75) instead of one fraction. Some shops also run multi-radius or “quad” style cuts on their own equipment. These are worth trying if a shop near you does them well, but they're not interchangeable with an ROH number, and not every shop can reproduce them.
New skates need a real first sharpening
Factory edges on new skates are inconsistent. Get a proper sharpening before your first skate, and tell the shop what hollow you want rather than taking the house default.
How often to sharpen, and keeping the edge you paid for
- Roughly every 6–10 hours of ice for a hard-skating player; 15–20 hours for a casual skater. Weight, ice hardness, and how much you stop all move that number.
- Sharpen immediately after a nick. One step onto concrete or a rubber-mat gap with a stray stone in it can flatten an edge in a single stride.
- The fingernail check. Lightly draw a thumbnail across the edge (across, never along it). A good edge catches and shaves a whisper of nail; a dull one slides right over.
- Every sharpening costs steel. Runners are consumable. Sharpening every week when you skate once a fortnight just buys you new steel sooner.
- Dry your blades every single time. Wipe them down before the skates go in the bag. Rust eats edges faster than skating does.
- Hard guards for walking, soakers for storage. Never store skates in hard plastic guards — they trap water against the steel.
Before you hand over your skates: say the number out loud — “five-eighths, please” — and ask them to check the edges are even when they're done. An uneven grind leaves one edge higher than the other, and it will feel like your skate is pulling to one side all night.
Need somewhere to get them done?
Our Hockey Shops directory lists pro shops and skate-sharpening spots across the U.S. and Canada — search by city and check hours before you drive over.
Find a hockey shop near you →Keep reading
Rink Lingo decodes the rest of the vocabulary you'll run into at the rink — freestyle, shinny, stick & puck, resurface, and every other line on a rink schedule. Find a Rink if you need ice near you, and Hockey Training if you'd rather fix your edges with your legs than with a grinder.