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Quantum Fiber vs Xfinity in Mercer Island
Quantum Fiber undercuts Xfinity by $10/mo with a higher speed score, but only reaches about half of Mercer Island while Xfinity covers nearly every address.
Xfinity wins Mercer Island on availability, reaching about 100% of the city versus Quantum Fiber’s roughly 49%, so it’s the safer bet if you just want service that works at your address. But where Quantum Fiber’s fiber is available, it’s the better value: $30/mo versus $40/mo, plus a slightly higher speed score (97 vs 95). Both top out at 2,000 Mbps download, though Xfinity also offers 2,000 Mbps upload versus Quantum’s 1,000. Choose Quantum Fiber for price and symmetrical-ish fiber if you can get it; choose Xfinity for certainty.
At a glance
Quantum Fiber vs. Xfinity, side by side.
| Provider | Type | Top speed | City coverage | Starting price | Best for |
|---|---|---|---|---|---|
| Quantum Fiber |
Fiber | 2 Gig 1 Gig upload |
49% | $30/mo | Top fiber speeds |
| Xfinity |
Cable | 2 Gig 2 Gig upload |
100% | $40/mo | Widest availability |
Coverage map
Two different questions, two views. Top speed shows who offers the faster plan where you can actually get it. Coverage shows who reaches more of each ZIP. Or pick a single provider to see just its footprint.
Neighborhood breakdown
Coverage is the deciding factor and it shifts block to block on Mercer Island. Xfinity reaches close to 100% of the island, so it’s likely an option almost anywhere, while Quantum Fiber’s roughly 49% footprint means fiber may be live on one street and not the next. Always run an address check before assuming either is available at your specific home.
| ZIP | Neighborhoods | Coverage | Top speed | Speed Score | Winner | |||
|---|---|---|---|---|---|---|---|---|
| Quantum Fiber | Xfinity | Quantum Fiber | Xfinity | Quantum Fiber | Xfinity | |||
| 98040 | North End, East Seattle, First Hill, South End | 49% | 100% | 2 Gig | 2 Gig | 87 | 96 | Xfinity |
Speed Score (0–100) blends each provider’s coverage and top speed in that specific ZIP, so it moves as availability changes street to street.
Which is better for…
The right pick comes down to what you actually do online.
Get connected
Pick your provider and check availability at your address.
- 2 Gig down · 1 Gig up Fiber
- 1 Gig down · 1 Gig up Fiber
- 2 Gig down · 2 Gig up Cable
- 2 Gig down · 300 Mbps up Fiber
See what’s actually available at your address
Coverage changes from one street to the next. Check your exact address in seconds.
Check my addressFrequently asked questions
Is Quantum Fiber available on Mercer Island or do I have to get Xfinity?
Quantum Fiber covers about 49% of Mercer Island, while Xfinity reaches roughly 100%, so Xfinity is more likely to serve your address. Enter your exact address on both providers’ sites to see which are live on your block before deciding.
Which is actually cheaper on Mercer Island, Quantum Fiber or Xfinity?
Quantum Fiber starts at $30/mo versus Xfinity’s $40/mo, making Quantum the cheaper listed option where available. Note these are promotional starting rates, so confirm the post-promo price, equipment fees, and any contract terms with each provider before you sign.
Which is faster and is it enough for gaming, working from home, and 4K?
Both top out at 2,000 Mbps download, with Quantum Fiber scoring 97/100 and Xfinity 95/100 on speed score, so either is far more than enough for gaming, WFH, and 4K. For upload-heavy work, note Xfinity offers up to 2,000 Mbps up versus Quantum’s 1,000 Mbps where available.