Washington / Seattle / Quantum Fiber vs Xfinity

Quantum Fiber vs Xfinity in Seattle

Quantum Fiber undercuts Xfinity on price and multiplies its upload speed, but Xfinity covers nearly all of Seattle while fiber reaches only about three in four homes.

The 30-Second VerdictUpdated August 7, 2026

Quantum Fiber is the better deal on paper: cheaper at $30/mo, symmetrical speeds up to 8,000 Mbps where available, and a near-perfect 99/100 speed score. But Xfinity reaches ~98% of Seattle versus Quantum’s ~76%, so availability may decide it for you before price does. Pick Quantum Fiber if fiber is live at your address and you want top speed for less. Pick Xfinity if you want the widest coverage and still-fast cable at 2,000 Mbps down.

At a glance

Quantum Fiber vs. Xfinity, side by side.

Provider	Type	Top speed	City coverage	Starting price	Best for
Quantum Fiber	Fiber	8 Gig 8 Gig upload	76%	$30/mo	Top fiber speeds
Xfinity	Cable	2 Gig 300 Mbps upload	98%	$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.

View

Showing the provider with the faster available plan in each ZIP. Click any ZIP for the breakdown.

Neighborhood breakdown

Coverage swings block to block in Seattle, so the winner can flip within a single neighborhood. Xfinity’s ~98% reach makes it a safe bet almost citywide, while Quantum Fiber’s ~76% footprint means it may be live on one street and absent the next. Always run an address check before assuming fiber is an option.

ZIP	Neighborhoods	Coverage		Top speed		Speed Score		Winner
ZIP	Neighborhoods	Quantum Fiber	Xfinity	Quantum Fiber	Xfinity	Quantum Fiber	Xfinity	Winner
98103	Fremont, Wallingford, Greenwood, Green Lake	91%	100%	8 Gig	2 Gig	97	96	Quantum Fiber
98115	Wedgwood, View Ridge, Bryant, Maple Leaf	81%	100%	8 Gig	2 Gig	95	96	Xfinity
98144	Beacon Hill, Mount Baker, Leschi, Judkins Park	74%	92%	8 Gig	2 Gig	94	94	Xfinity
98108	Georgetown, Beacon Hill, South Park	67%	80%	8 Gig	2 Gig	93	92	Quantum Fiber
98118	Columbia City, Rainier Valley, Seward Park, Hillman City	88%	99%	8 Gig	2 Gig	97	96	Quantum Fiber
98117	Ballard, Crown Hill, Loyal Heights, Sunset Hill	94%	100%	8 Gig	2 Gig	98	96	Quantum Fiber
98133	Bitter Lake, Broadview, Haller Lake, North Seattle	67%	100%	8 Gig	2 Gig	93	96	Xfinity
98122	Central District, First Hill, Madrona, Leschi	54%	99%	8 Gig	2 Gig	90	96	Xfinity
98126	West Seattle, Delridge, North Delridge, Genesee	91%	98%	8 Gig	2 Gig	97	96	Quantum Fiber
98168	Tukwila, Riverton, Boulevard Park, White Center	67%	98%	2 Gig	2 Gig	93	96	Xfinity
98125	Northgate, Lake City, Maple Leaf, Pinehurst	88%	100%	8 Gig	2 Gig	97	96	Quantum Fiber
98105	University District, Ravenna, Laurelhurst, Roosevelt	62%	100%	8 Gig	2 Gig	92	96	Xfinity
98178	Rainier Beach, Bryn Mawr, Skyway, Lakeridge	74%	98%	8 Gig	2 Gig	94	96	Xfinity
98198	Des Moines, Redondo, Woodmont	17%	99%	8 Gig	2 Gig	83	96	Xfinity
98112	Madison Park, Montlake, Madison Valley, Capitol Hill	75%	100%	8 Gig	2 Gig	94	96	Xfinity
98155	Lake Forest Park, Shoreline, Kenmore	82%	100%	8 Gig	2 Gig	96	96	Xfinity
98109	South Lake Union, Queen Anne, Westlake	52%	99%	8 Gig	2 Gig	90	96	Xfinity
98177	Broadview, Blue Ridge, North Beach, Carkeek Park	47%	100%	8 Gig	2 Gig	89	96	Xfinity
98107	Ballard, Adams, Loyal Heights	79%	100%	8 Gig	2 Gig	95	96	Xfinity
98119	Queen Anne, Interbay, Uptown	67%	98%	8 Gig	2 Gig	93	96	Xfinity
98116	West Seattle, Alki, Admiral, Fauntleroy	94%	100%	8 Gig	2 Gig	98	96	Quantum Fiber
98146	White Center, Highland Park, West Seattle, Arbor Heights	90%	100%	2 Gig	2 Gig	97	96	Quantum Fiber
98136	West Seattle, Fauntleroy, Fairmount Park, The Junction	94%	100%	8 Gig	2 Gig	98	96	Quantum Fiber
98102	Capitol Hill, Eastlake, Montlake	62%	100%	8 Gig	2 Gig	92	96	Xfinity
98104	Pioneer Square, Chinatown-International District, First Hill	16%	82%	8 Gig	2 Gig	82	92	Xfinity
98106	Highland Park, South Delridge, Riverview	90%	99%	8 Gig	2 Gig	97	96	Quantum Fiber
98188	Tukwila, Riverton Heights, McMicken Heights	36%	95%	8 Gig	2 Gig	86	95	Xfinity
98199	Magnolia, Lawton Park, Interbay, Discovery Park	72%	99%	8 Gig	2 Gig	94	96	Xfinity
98134	SoDo, Industrial District, Georgetown	30%	76%	8 Gig	2 Gig	85	91	Xfinity
98148	Burien, Normandy Park, SeaTac	46%	99%	8 Gig	2 Gig	88	96	Xfinity
98166	Burien, Normandy Park, Three Tree Point	61%	100%	2 Gig	2 Gig	91	96	Xfinity
98101	Downtown, Retail Core, Denny Triangle	11%	95%	8 Gig	2 Gig	81	95	Xfinity
98194	Downtown Seattle, Pioneer Square, Waterfront	25%	69%	8 Gig	2 Gig	84	90	Xfinity
98124	Downtown Seattle, Central Business District	30%	76%	8 Gig	2 Gig	85	91	Xfinity
98139	Interbay, Magnolia	49%	100%	2 Gig	2 Gig	89	96	Xfinity
98121	Belltown, Denny Regrade, Waterfront	17%	97%	8 Gig	2 Gig	83	95	Xfinity
98138	Tukwila	13%	94%	2 Gig	2 Gig	82	95	Xfinity
98113	Northgate, Ballard	100%	100%	2 Gig	2 Gig	99	96	Quantum Fiber
98111	Downtown Seattle, Central Business District	18%	93%	8 Gig	2 Gig	83	95	Xfinity
98164	Downtown Seattle, Pioneer Square	18%	93%	8 Gig	2 Gig	83	95	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.

Gaming

Quantum Fiber

Fiber’s symmetrical 8,000 Mbps and 99/100 speed score give lower, more stable latency than Xfinity’s cable, where available. Great for competitive play and large game downloads.

Streaming

Xfinity

Xfinity’s 2,000 Mbps down easily handles multiple 4K streams, and its ~98% coverage means it’s far more likely to actually be available at your Seattle address.

Video calls

Quantum Fiber

Symmetrical uploads up to 8,000 Mbps crush Xfinity’s 300 Mbps upload, keeping your video sharp on long calls and big file shares, where available.

Just the basics

Quantum Fiber

At $30/mo it’s the cheaper plan and still enormously overpowered for browsing and email, so you pay less for more if fiber reaches you.

Get connected

Pick your provider and check availability at your address.

Check plans

Top speed8 Gig

Upload8 Gig

Coverage76%

From$30/mo

8 Gig down · 8 Gig up Fiber
2 Gig down · 1 Gig up Fiber
1 Gig down · 1 Gig up Fiber

Check plans

Top speed2 Gig

Upload300 Mbps

Coverage98%

From$40/mo

2 Gig down · 300 Mbps up Cable
2 Gig down · 300 Mbps up Fiber
1 Gig down · 35 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.

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Frequently asked questions

Is Quantum Fiber available at my address in Seattle or only Xfinity?

Quantum Fiber reaches about 76% of Seattle while Xfinity covers roughly 98%, so Xfinity is more likely available but fiber may still be live on your block. Enter your exact address on each provider’s checker before deciding, since coverage varies block to block.

Which is actually cheaper, Quantum Fiber or Xfinity, and what will I really pay?

Quantum Fiber starts at $30/mo versus Xfinity at $40/mo, making fiber the cheaper headline price. Note these are promotional starting rates, so confirm the post-promo rate, any equipment fees, and contract terms with each provider before you sign.

Which is faster and is it enough for gaming, working from home, and 4K?

Quantum Fiber is faster with up to 8,000/8,000 Mbps and a 99/100 speed score, versus Xfinity’s 2,000/300 Mbps and 95/100, where fiber is available. Both handle gaming, WFH, and 4K easily, so if you upload a lot pick fiber; otherwise confirm which is at your address.

How we compare. Coverage is the share of a ZIP where a provider offers a genuinely good plan (≥ 1 Gbps download, ≥ 20 Mbps upload, non-satellite), from FCC Broadband Map serviceability data. “Fastest available” ranks the providers present in a ZIP by top advertised download speed. Pricing reflects current promotional starting rates. This is a working prototype; production copy is generated per matchup.