The decision is area, not brand
None of the five records here publish a melt rate, so there is nothing to rank on that axis — every embedded-cable maker on the market claims fast melting and none backs it with a measured number. What actually separates these five SKUs is heated coverage: 20 sq ft, 30 sq ft, 60 sq ft, 90 sq ft, and 100 sq ft, all at a published 48–50.09 W/sq ft. The only decision that matters, and the one you can only make while the forms are still open, is matching that coverage to the part of the slab you actually drive and walk on.
Measure the tire tracks and the path to the door, not the whole slab
A full two-car driveway slab is usually 500–700 sq ft. None of these mats are sized for that, and none need to be. Snow melting only earns its keep where wheels and feet land: the two tire tracks from the street to the garage, and the walk from the driveway to the door. That footprint is commonly a fraction of the poured area — which is exactly why WarmlyYours publishes this cable in four coverage sizes (WHMA-240-0210 at 20 sq ft, WHMA-240-0215 at 30 sq ft, WHMA-240-0320 at 60 sq ft, WHMA-240-0250 at 100 sq ft) rather than one. Before ordering, measure the actual square footage of the tracks and the walk with a tape, not an eyeball estimate off the driveway plan — a 20 sq ft mat and a 100 sq ft mat differ by 5x in both price and amp draw, so the measurement is the whole exercise.
The tradeoff runs the other way too: undersizing to save money on the mat leaves bare concrete right where a tire or a boot lands, which defeats the purpose of installing anything. Get the footprint right before the pour, because embedded cable cannot be resized after the concrete cures.
48 W/sq ft and 50 W/sq ft — and why the published figure is worth trusting
WarmlyYours publishes 50 W/sq ft flatly across all four of its coverage sizes recorded here — the 20 sq ft WHMA-240-0210 (1,000 W total), the 30 sq ft WHMA-240-0215 (1,500 W), the 60 sq ft WHMA-240-0320 (3,000 W), and the 100 sq ft WHMA-240-0250, which runs slightly hotter at 50.09 W/sq ft (5,009 W total). All four numbers — total watts, W/sq ft, and amp draw — come off the manufacturer’s own product pages as stated specifications, not calculations.
ThermoSoft’s TSMM030W36-240 publishes 48 W/sq ft for its 90 sq ft mat, and that per-square-foot figure is also a manufacturer spec. But ThermoSoft does not publish a total-watt number for this SKU — the 4,320 W figure on this page is derived, 48 W/sq ft × 90 sq ft, and 240 V × the published 18.1 A draw lands on a slightly different number, which is ordinary rounding in the published per-sq-ft figure rather than a discrepancy worth chasing. The distinction matters because a derived total is an arithmetic convenience for comparison, not a manufacturer claim — if ThermoSoft ever publishes a total-watt figure for this model, it supersedes the derived one here.
This is also the rare case on this site where wattage doesn’t need hedging into a VA range: all five records publish a real watt figure or a real per-sq-ft figure with no stated tolerance, unlike portable mats, where amp figures often carry a manufacturer tolerance and total wattage frequently goes unpublished entirely.
Price per square foot falls sharply — with one exception
Mat price alone (not installed cost) runs:
- WHMA-240-0210, 20 sq ft: $319 → $15.95/sq ft
- WHMA-240-0215, 30 sq ft: $449 → $14.97/sq ft
- WHMA-240-0320, 60 sq ft: $739 → $12.32/sq ft
- TSMM030W36-240, 90 sq ft: $889.97 → $9.89/sq ft
- WHMA-240-0250, 100 sq ft: $1,089 → $10.89/sq ft
The pattern is what you’d expect — cost per square foot drops as the mat gets larger, because the cold lead and connection hardware are a fixed cost spread over more cable. It isn’t perfectly monotonic: the 100 sq ft WarmlyYours unit works out to $10.89/sq ft, a touch more than the 90 sq ft ThermoSoft mat at $9.89/sq ft, because they’re different products from different manufacturers, not points on one continuous curve. Read the per-square-foot column as “smaller costs more per foot,” not as a promise that the next size up is always cheaper per foot than every other brand’s equivalent size.
None of these five figures include the concrete or asphalt work, the control, or the electrician. WarmlyYours’ own published range for a fully installed embedded system — materials and labor together — runs $8–$25 per sq ft, so the mat price above is a fraction of what actually lands on an invoice. Budgeting off the mat price alone will understate the job by a wide margin.
Amp draw at 240 V, and what each expects from a panel
All five mats run on a 240 V circuit, and all five publish amp draw as a flat figure with no stated tolerance:
- WHMA-240-0210 (20 sq ft): 4.17 A
- WHMA-240-0215 (30 sq ft): 6.25 A
- WHMA-240-0320 (60 sq ft): 12.5 A
- TSMM030W36-240 (90 sq ft): 18.1 A
- WHMA-240-0250 (100 sq ft): 20.87 A
That’s roughly a 5x spread from the smallest mat to the largest, which tracks the coverage spread rather than any efficiency difference between the two brands. Every record in this set carries the same manufacturer’s circuit note: this is an embedded system requiring a licensed electrician, a dedicated circuit, a snow-melt control, and ground-fault protection per NEC 426. That instruction applies whether the mat draws 4.17 A or 20.87 A — the difference is what breaker size and panel capacity the electrician needs to plan around, and at the top of this range, an older panel with limited spare capacity may need attention before the mat does. We don’t give hardwiring or breaker-sizing steps here; that’s a licensed electrician’s call, made against the specific panel, not a spec sheet.
If you’re weighing more than one mat size against the same panel, or stacking multiple mats, SnowWatt’s layout planner works from these same published coverage and amp figures.
No melt-rate claim appears on this page, on purpose
Every mat on the market — these five included — markets a melt-rate figure as a differentiator. It’s the manufacturer’s own marketing claim, not an independent measurement, and every product claims essentially the same thing. None of the five records here carry a meltRateInPerHr value we could report even if we wanted to lean on it, so this page compares the numbers that are actually published and measurable: coverage, watts, price, and amp draw.
Who should not buy from this list
If the driveway is already poured, none of these five products are for you — embedded cable goes in before or during the pour, set into wet concrete or asphalt, and retrofitting it means saw-cutting the existing slab, a different job with a different cost basis than anything on this page.
If you’re in a genuinely high-snowfall zone — the Sierra Nevada & Cascade communities average 184.9 in of snow a year, for instance — note that WarmlyYours’ own product notes recommend this exact 50 W/sq ft, 3-in-spacing configuration specifically “for regions with 60+ inches of annual snowfall or when rapid melting is critical.” ThermoSoft’s 48 W/sq ft mat sits just under that manufacturer’s own stated threshold; whether that gap matters for your climate is a question for the manufacturer or your electrician, not a call this page makes.
Two real costs to weigh before ordering: first, the mat price above is a small slice of the installed cost — concrete or asphalt work, the control, and licensed electrical labor are the majority of the bill and aren’t in these numbers. Second, at the top of this range the 100 sq ft mat’s 20.87 A draw is a meaningful electrical load to add to a panel that wasn’t planned around it, and finding that out after the pour is a worse position than finding it out before.
For the actual break-even math against a plow contract or a season of shoveling, SnowWatt’s break-even calculator works from the same published wattage and price figures used here, alongside your local electricity rate.
The shortlist, side by side
| Spec | WarmlyYours WHMA-240-0210 | WarmlyYours WHMA-240-0215 | WarmlyYours WHMA-240-0320 | WarmlyYours WHMA-240-0250 | ThermoSoft TSMM030W36-240 |
|---|---|---|---|---|---|
| Coverage | 20 sq ft | 30 sq ft | 60 sq ft | 100 sq ft | 90 sq ft |
| Amp draw | 4.17 A | 6.25 A | 12.5 A | 20.87 A | 18.1 A |
| Rated power | 1000 W | 1500 W | 3000 W | 5009 W | 4320 W |
| Watts per sq ft | 50 W/sq ft | 50 W/sq ft | 50 W/sq ft | 50.09 W/sq ft | 48 W/sq ft |
| Melt rate | not published | not published | not published | not published | not published |
| Weight | 6.4 lb | 8 lb | 14.2 lb | 22.8 lb | not published |
| Warranty | 10 yr | 10 yr | 10 yr | 10 yr | not published |
| Listed price | $319.00 | $449.00 | $739.00 | $1,089.00 | $889.97 |
| Cost per sq ft heated | $15.95 | $14.97 | $12.32 | $10.89 | $9.89 |
No winner is marked for coverage, amp draw, rated power, watts per sq ft, melt rate, weight, listed price, because every one of those scales with how big the product is — "lowest amps" would only ever mean "smallest mat". The comparison that survives a size difference is cost per square foot heated, and it is derived by us from the listed price and the coverage, not published by anyone. No winner is marked for warranty either — at least one product does not publish that figure. Declaring a winner across a blank or across a derived figure would invent a difference the sources do not support.
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