Get a realistic low, mid, and high price range for a roof replacement based on the cost drivers most online estimates ignore: your real roof area, layers to tear off, steepness, and material tier. Ballpark only, then get three local bids.
Ballpark only, not a quote. These ranges are computed from your inputs times published baseline ranges, not Kelly WM pricing data. Roof prices swing widely by region, crew, and what the deck looks like once the old roof is off. Always get three local bids before you commit.
There is no single answer, and any tool that hands you one flat number is guessing. A roof replacement price is built from a handful of cost drivers, and this estimator walks through the ones most homeowners miss. Enter your roof size and details above to get a low, mid, and high installed range, then read on so you can tell a fair bid from a lowball one. This is a ballpark for planning, not a quote, and the numbers are never presented as our own pricing data.
The biggest reason a modest estimate and an estimate two or three times larger can both be honest is that the roof itself is more complicated than its floor plan. Here is what actually moves the price, and what each input above is doing:
Our estimator measures cost in squares (one square equals 100 sq ft of roof surface, the unit roofers and suppliers actually use) and applies these drivers to a published baseline range to produce your low, mid, and high numbers.
Homeowners are often shocked when three bids for the same house land thousands of dollars apart. Most of that spread is real, and learning to read it protects you:
The fix is not to chase the lowest total. Get every bid to itemize tear-off, decking allowance, flashing, accessories, permit, and warranty, then compare line by line. A mid-priced bid with a complete scope usually beats a cheap one with blanks.
An overlay (sometimes called a re-cover) lays new shingles directly over the existing layer. A tear-off strips the roof down to the decking first. Overlay is cheaper up front because it skips tear-off labor and disposal, and that gap is exactly why some bids look like a steal.
But the savings come with strings. An overlay hides the decking, so rot and soft spots go unseen and unrepaired. It piles extra weight on the structure, traps heat that ages the new shingles faster, and rarely lasts as long. Most building codes allow only two total layers, so a second overlay is usually off the table, and many manufacturer warranties are void on an overlay. A full tear-off lets the crew inspect and repair the deck, install fresh underlayment, and gives you the longer-lasting, warrantied result. If a roof is near the end of its life or you plan to stay in the home, tear-off is almost always the better long-run value even though the sticker is higher.
If your roof is in Florida (or another hurricane-exposed coast), the price math shifts and you should verify the current rules with your local building department, because codes change. A few factors that commonly raise the number:
On the insurance side, if storm damage is involved, your out-of-pocket cost is often closer to your deductible plus any upgrades than the full roof price, because an approved claim covers the covered portion. Read your policy for hurricane vs standard deductibles, document damage, and be cautious of any contractor who offers to waive or absorb your deductible, which can be illegal. None of that is a quote, it is context, so still get three local bids.
The Pro version drops this tool onto your own domain with your logo, your per-square rates and material tiers, your service-area pricing, and a lead capture that emails or texts you the moment a homeowner finishes an estimate. Qualify roof shoppers before the phone even rings.
Get early access, book a free call →Everything starts with geometry. The footprint you enter is the ground your roof covers, not the roof itself, so the tool multiplies it by a pitch factor, from 1.02 on a low slope up to 1.42 on a 12/12, to reach actual roof surface. That surface divides into squares of 100 square feet, the unit roofers and suppliers price in. An 1,800 square foot footprint on a common pitch works out to roughly 20 squares.
Each square then gets a low and a high figure: installed material cost for your tier, plus $100 to $175 per layer of old roofing to strip and haul away, plus a decking allowance if you flagged the deck as questionable. Three multipliers for steepness, complexity, and stories apply on top, and permit and dumpster arrive as a flat allowance for the job. The material ranges come from public remodeling cost guides, Angi, Fixr, Forbes Home, This Old House, and per-square roofing references, last reviewed June 6, 2026. They are not Kelly WM pricing, and we do not sell roofs.
Two things deserve saying out loud. The multipliers compound: very steep plus complex plus three stories stacks to roughly 1.9 times, and they apply to the whole per-square figure including material, so read them as a rough labor and waste allowance, not a precise surcharge. And the tool cannot see your roof. It does not know how many planes, dormers, or valleys you really have, what the decking looks like under the old shingles, what a crew charges in your zip code, or what your local code requires for underlayment and fastening. The decking line is a contingency, not a finding. Use the range to read three written bids, then go get them. Other estimating tools sit in the free tools library, and a free mockup is the place to start if you want one on your own site.
Because a sloped roof covers more surface than the ground beneath it, and the steeper the pitch the wider the gap. A gentle slope adds a few percent. A 12/12 adds more than 40. That is why an estimate built off a floor plan comes in low, and why this tool asks for pitch before it prices anything. If you already have a real roof measurement from an aerial report, note that the calculator expects the footprint and adds the slope itself.
Only if you tell it to. Tear-off is priced per layer, so selecting none, right for new construction or an overlay, drops that line entirely. Permit and dumpster are an include or exclude switch, set to include because most reroofs require both. Before you decide a bid is high, check that it contains the same items.