K-style or half round
By Gutter Report Editorial. Last reviewed August 2026. How we research this.
In brief
Pick K-style unless the house argues against it. It costs $1 to $2 a foot less in the same metal, it screws straight to the fascia with no brackets to buy, and every seamless machine on every truck is set up to roll it. Half round is right on a period house where the ogee front of K-style reads wrong, and it is right if you want the rounded bottom, which Texas A&M AgriLife Extension recommends because it limits debris buildup. That is the whole decision, and it is mostly about how the house looks. The trade sells it as a performance choice and the published capacity numbers do not support that: the two figures usually quoted come from different tables that were never meant to sit together. Treat half round as the smaller gutter at the same nominal width and size accordingly.
1.0The two profiles, side by side
| K-style | Half round | |
|---|---|---|
| Shape | Ogee curved face, boxed top bead, stepped bottom | A semicircle |
| Back | Flat. Screws to the fascia | None. Hangs in brackets or straps |
| Installed price | The baseline | $1 to $2 a foot more, per HomeGuide |
| Hardware | Hidden hangers, about 24 in. apart | Fascia brackets, 32 in. apart at one supplier |
| Sizes | 4 to 8 in. Most houses use 5 | 4 to 8 in. Most houses use 5 or 6 |
| Seamless | Every machine rolls it | Available, fewer contractors tooled for it |
| Cleaning | Flat floor and inside corners hold grit | Rounded bottom sheds debris better |
| Looks right on | Postwar and contemporary houses | Colonial, Victorian, Tudor, Craftsman |
The bracket row is the hidden cost. K-style hangers cost a couple of dollars each. Half round brackets at Classic Gutter Systems run $3.85 in Galvalume, $6.80 for 6 inch, and $10.45 for 5 inch copper. At 32 inch spacing, 150 feet of gutter takes about 57 brackets, so the hardware alone is roughly $220 in Galvalume and about $600 in copper. That arithmetic is ours.
2.0What the price difference actually is
| Source | K-style | Half round | Premium |
|---|---|---|---|
| USD / FT | USD / FT | USD / FT | |
| HomeGuide, all materials, stated outright | n/a | n/a | +$1 to $2 |
| Angi, seamless, installed (2026) | $8 to $15 | $9 to $17 | +$1 to $2 |
| Fixr, copper, installed (Jan 2025) | $26 to $37 | $27 to $40 | +$1 to $3 |
| Modernize calculator (Aug 2026) | $9 to $30 | $13 to $35 | +$4 to $5 |
Three of four agree on $1 to $2. Put that next to the material decision, where moving from aluminum to copper costs $15 to $30 a foot more, and the profile premium is roughly a tenth the size. Profile is the cheap part of this project.
Supplier stock prices tell the same story from the other end. A 5 inch aluminum half round is $3.58 a foot at Classic Gutter Systems and $6.00 at The Home Depot, which is a 68 percent seller premium on the same .027 spec. That is our arithmetic on the 10 foot section price. Where your contractor buys moves the bill more than the profile does.
3.0The capacity claim, examined
This is where the profile decision gets dressed up as an engineering one, so it is worth taking apart.
| Gutter | Published drainage area | Where the number comes from |
|---|---|---|
| SQ FT of roof | ||
 | 5,520 | Fine Homebuilding, at 1 in. of rain per hour |
| | 7,960 | This Old House, basis not stated |
 | 2,500 | Matches a legacy semicircular code value at 1/4 in. per ft slope |
| | 3,840 | This Old House, basis not stated |
Read down the last column. The K-style rows and the half round rows do not share a method. A 5 inch half round is a 5 inch wide semicircle, about 9.8 square inches of cross section, which is our arithmetic on the diameter. Yet the table hands the K-style 2.2 times the drainage area at the same nominal width.
The two figures trace to different documents. So the honest reading is that no publisher has measured these two profiles against each other on one method, and the 2.2 times gap is a publishing artifact rather than a test result.
What survives is the qualitative claim, which This Old House states directly: half round carries less volume at the same width and moves water more smoothly. Both are consistent with the geometry. So size half round conservatively. If a 5 inch K-style would have been marginal on your roof, go to 6 inch half round rather than 5, or add an outlet.
And one number the reprints drop entirely. Fine Homebuilding states 5,520 square feet at one inch of rain per hour, then divides by Washington DC's five minute intensity of 6.6 inches per hour to get 836 square feet of real maximum roof area. Any page quoting 5,520 as a usable roof area is off by roughly seven times, whichever profile it is describing.
Beads, backs and the parts that are not interchangeable
If you are extending or repairing rather than replacing everything, the sub-type matters and it is easy to order wrong.
Half round beads. Berger and Amerimax both list single bead, single bead with a 1 inch flange, double bead and reverse bead. Reverse bead turns the lip outward and is common on newer installs. Price follows: Seamless Gutter Supply's 6 inch copper reverse bead is $20.42 a foot while Classic Gutter Systems' 6 inch classic bead copper is $13.03, and part of that 36 percent gap is the bead rather than the seller.
K-style backs. Berger lists hemback, straight back, hi-back at 45 degrees and apron at 90 degrees. Hi-back and apron exist to stop water that runs behind the drip edge from getting between the gutter and the fascia. If your fascia is rotting behind a gutter that otherwise works, that is the problem those backs solve.
Thickness. Amerimax lists straight back K-style at .0185, .0255 and .0305 inch, and hem back at .027 and .032. Berger runs galvanized K-style at 26 gauge, and on steel a lower gauge number means thicker metal. Ask which brand and which gauge.
4.0The verdict
| Your situation | Pick |
|---|---|
| Ordinary postwar or newer house | K-style, 5 inch, seamless |
| Colonial, Victorian, Tudor or Craftsman you care about | Half round, and size up one step |
| Buying copper | Half round. It is the shape copper is chosen for, and the premium is $1 to $3 a foot on a job already past $5,000 |
| Heavy leaf load and you hate cleaning | Half round for the rounded bottom, or K-style plus a guard decision |
| Matching an existing run | Whatever is up there, and match the bead or the back too |
| Tightest possible budget | K-style. It is cheaper at every step, including the hangers |
5.0You may not need to change profile
Switching profiles on an existing house is one of the more expensive changes for the least performance gain. It means new hangers or brackets, new outlets and new end caps along the whole run, for a gutter that drains no better and possibly worse.
If the complaint is overflow, the profile is not the answer. Fine Homebuilding states that adding a second downspout doubles the roof area a run can drain, and pitching a gutter at 1/8 inch per foot multiplies it by 1.4. Both cost far less than re-hanging the house. See how many downspouts and gutter slope.
If the complaint is a drip or a sag, it is a seam or a hanger, and a repair at a national average of $275 covers it. Work through repair or replace first. We can say that plainly because we do not sell gutters and we do not install them.
Get a quote in the profile you picked
If you want half round, ask whether they can roll it seamless or will be joining sections. Tell us your ZIP code and we will pass your details to one licensed contractor who works there.
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Common questions
Which is better, K-style or half round?
For nearly every house, K-style, because it is cheaper to buy, cheaper to hang and it is what every seamless machine is set up to roll. Half round is the right choice when the house is a period style where the ogee face of K-style looks wrong, or when you want the rounded bottom that sheds debris better. That is an appearance and maintenance decision, not a drainage one.
How much more do half round gutters cost?
HomeGuide says $1 to $2 a foot more in the same material. Angi agrees, pricing seamless K-style at $8 to $15 a foot installed against half round at $9 to $17. Fixr shows the same $1 to $3 gap on copper. Modernize is the outlier at $4 to $5. On top of that, half round hangs in brackets rather than on the fascia, and those are priced per piece.
Does half round carry less water than K-style?
This Old House says yes, that half round flows more smoothly but carries less volume at the same width. Its published roof area figures give a 5 inch K-style 5,520 square feet and a 5 inch half round 2,500, but those two numbers come from different tables that were never meant to sit together. Treat half round as the smaller gutter at the same nominal size, and size up or add a downspout if the roof is large.
Is half round easier to clean?
The rounded bottom helps. Texas A&M AgriLife Extension recommends rounded bottom gutters because they limit debris buildup, and This Old House agrees water moves through them more smoothly. There is no flat floor and no inside corner for grit to sit in. It does not make them self cleaning, and leaves still land in them.
Can I get half round in seamless?
Yes, in aluminum and copper, though fewer contractors carry the tooling for it than for K-style. Seamless Gutter Supply sells a 6 inch aluminum half round in reverse bead by the foot at $5.44. Ask before you assume: a contractor whose machine only rolls K-style will quote sectional half round without saying so.
What is a bead, and does it matter?
The rolled edge at the top of a half round, and yes, if you are matching an existing run. Berger and Amerimax both list single bead, single bead with a 1 inch flange, double bead and reverse bead. They are not interchangeable, and the price differs: a 6 inch copper reverse bead runs $20.42 a foot at one supplier against $13.03 for a classic bead at another.
- Rev
- RevAugust 2026
- Source
- SourceHomeGuide, Angi, Fixr, Modernize, Berger, Amerimax, This Old House, Fine Homebuilding (read 2026-08-21)