Every House Has a Number. Measure It Before You Price It.
Siding Calculator exists for the moment a re-side project stops being an idea and starts being an order — the takeoff. Walls measured, gables counted, openings deducted, waste added, and the whole thing converted into the squares, cartons, and trim pieces that siding is actually bought in. One free tool, one published method, and every assumption in plain sight.
One tape measure, one method, one defensible numberPhoto: Unsplash10
Profile presets with real carton coverage
100
Sq ft in a square — the unit siding is sold in
5
Stops from tape measure to order sheet
3-way
Cost split: material, labor, tear-off
0
Accounts, uploads, or paywalls
Why this site exists
Siding is the project where measurement failure hides in plain sight. A roof leak announces itself; an under-ordered siding job just stalls on day three, when the crew discovers that the pallet holding forty cartons was calculated for a house with no gables. On the other side, over-ordering hurts quietly: siding is largely non-returnable, dye lots shift between production runs, and a garage bay of leftover cartons is the most expensive yard art a homeowner can own. The gap between those two failures is a takeoff done properly — and for decades the only people with a fast, reliable takeoff were the ones who did it every week.
Look at what most of the internet offers instead. Widget calculators that ask for one “total wall area” and quietly assume a house shaped like a shoebox. Supplier pages that turn a measurement question into a consultation funnel. Forum answers that say “measure everything” without saying what to do with the measurements next. Meanwhile the real decisions — how many cartons, how many corner posts, whether that quote is light by a square or a third — wait on a number nobody wants to produce twice.
We built SidingCalculator.net to close that gap with the boring, correct version of the trade’s own method: gross wall + gable area − openings + waste → squares, cartons & trim. No average-wall shortcuts. No mystery constants. The profile presets carry the exposures and carton coverages manufacturers actually print, every one is editable, and the cost comes back split into material, labor, and tear-off because those are the three lines real budgets are argued over. The calculator is the product; this page is the contract — how the engine works, what it promises, and the standards the guides around it answer to.
No two houses measure alike — the tool never assumes they doPhoto: UnsplashFrom tape measure to order sheet, in five stops
Every input follows the same chain, and the chain is public. Because the method never changes, two people measuring the same house can compare numbers line by line — and two answers from this tool are mathematically impossible.
Stop 1
Measure the Walls
Width × height for every rectangular face of the house — front, back, both sides, plus dormers, porch returns, and bump-outs the tape says are real. The calculator holds an unlimited list of wall sections instead of one average wall, because no house is one average wall.
Stop 2
Add the Gables
Every triangular peak is base × height ÷ 2. Gables are where naive estimates bleed the most — a 24 ft gable with an 8 ft rise hides another 96 sq ft of coverage that a rectangle-only estimate never sees.
Stop 3
Deduct the Openings
Doors, windows, and garage doors are preset sizes you click, or custom areas you type. What comes back is the net area — the surface that will actually wear siding, not the surface the blueprint wishes existed.
Stop 4
Apply the Waste Factor
Lap siding is cut at every opening, every corner, and every course stagger. Ten percent waste is the industry's quiet default; the calculator makes it visible, adjustable, and honest — 10% default, 15% for complex rooflines, your call for anything else.
Stop 5
Convert to Purchase Units
Siding is not sold by the square foot. It is sold by the square (100 sq ft) and by the carton, and each profile's carton covers a different area. The engine rounds up — because a fraction of a carton is not a thing you can buy.
10 Profile Presets, Real Carton Math
- Vinyl Double 4, 4.5, and 5 with their 200 / 180 / 160 sq ft carton coverages
- Lap and clapboard at 4, 6, and 8 inch exposures, fiber cement at 6 and 7.25
- Metal corrugated and board & batten round out the profiles contractors actually hang
- Override any preset — exposure, carton coverage, and price all accept your manufacturer's numbers
Opening Deductions Without the Arithmetic
- Standard door, window, and garage-door sizes as one-click presets
- Custom-area openings for arched windows, odd bulkheads, and anything non-standard
- Known-area sections for surfaces you already measured, in sq ft or m²
Trim and Accessories Included
- J-channel, inside and outside corners, starter strip, and fascia estimated from your perimeter and openings
- Standard 10 ft and 12 ft piece lengths, always rounded up so the job never runs short
- The pieces that stall a job on day three are priced on day one
A Cost Breakdown, Not One Blurry Number
- Material cost from the unit price you set per square foot
- Labor cost computed on the net installed area, the way siding crews quote it
- Tear-off cost carried as its own line for stripping old siding
- Per-sq-ft and per-square figures shown side by side for quote-checking
Five audiences, one takeoff
A homeowner with three quotes, a DIYer with a Saturday calendar, and a crew lead booking material all want the same number — they just read different lines of the result. These are the people we design for.
Homeowners Planning a Re-Side
You have three contractor quotes that disagree by $4,000 and no way to tell which one is anchored to reality. Run your own takeoff first: walls, gables, openings, waste. Then the quotes become negotiable objects instead of mystery numbers — and you know whether the 'extra' square someone tacked on is prudence or padding.
DIYers on Their First Big Project
Re-siding your own garage or ranch is one of the last doable big-ticket projects — if you buy the right amount. The calculator walks the same takeoff sequence a contractor uses, converts it into cartons for the profile you picked, and adds the trim list that first-timers always forget until the J-channel runs out on a Saturday.
Contractors & Crews
Fast estimates between site visits, consistent waste assumptions across every estimator in the company, and a material list the supply house can fill directly — squares, cartons, trim pieces. When a customer's 'other quote' looks light, your math is on the table, line by line, to compare against.
Estimators & Property Managers
Multi-property portfolios mean the same estimate, repeated. A fixed takeoff method turns re-sides across a dozen rentals into a routine: same inputs, same waste logic, same trim math — numbers you can defend to owners, insurers, and the board without re-deriving them each time.
Flippers & Buyers
Standing in the driveway of a potential purchase, the question is what the re-side costs, not whether it needs one. Two minutes with a tape measure and this calculator converts a cracked, chalky facade into a budget line — before the inspection contingency, while there is still time to use it in the offer.
The common thread
Every audience above needs the same five numbers — net area, squares, cartons, trim pieces, and a cost split — and needs them defensible. Not “the internet said so,” but here is the wall list, here is the waste logic, here is the carton math. That defensibility is what turns a siding budget from an opinion into an order.
Six decisions a takeoff feeds
The area number is never the deliverable — the budget, the order, the quote comparison, and the delivery plan are. Here is where the output goes once the engine is done with it.
The Project Budget
Material, labor, and tear-off priced separately means the budget has parts you can flex. Trim the profile price, keep the labor; delay the tear-off a season. A split estimate bends; a single number just snaps.
The Material Order
Squares and cartons rounded up, trim pieces rounded up, one extra carton for the inevitable repair a few years out. The order sheet this calculator produces is the one the supply house expects to receive.
Quote Comparison
When quotes arrive, compare each against your net area and your squares. A quote far below your material-alone figure is not a bargain — it is a question you should ask out loud before signing.
Delivery & Staging
Twenty cartons of fiber cement weigh real tons. Knowing the order size before delivery day means the driveway holds the pallet, the crew is booked for the unload, and the neighbor's hydrant survives the forklift turn.
Color Batch Planning
Siding dye lots shift between production runs, and an off-shade patch panel is visible from the street. The calculator's extra-carton logic exists for exactly this — order the repair stock with the job, not after the job.
DIY-vs-Hire Decision
Material at $6/sq ft plus labor at $3 changes character when you supply the labor. The split cost lines let you price both worlds honestly — including the tear-off nobody prices until the dumpster is already ordered.
Cartons, corners, and J-channel — counted before the crew arrivesPhoto: UnsplashWhat we promise — and what we don’t
An estimator earns trust by being precise about its own limits. Here is the complete list of both.
The trade's own method
Gross wall + gable area, minus openings, plus waste, converted to squares and cartons — the same sequence every siding estimator and supply counter has used for decades. Nothing exotic, nothing hidden.
Manufacturer numbers first
Profile presets ship with typical exposures and carton coverages, but every preset is editable. Your carton label beats our default — always, and by design.
Waste made visible
Ten percent is the default, not a hidden constant. Complex rooflines need more; long unbroken walls need less. The tool shows the lever so you can pull it, rather than burying it in a footnote.
Rounding that favors the job
Partial squares and partial cartons round up, trim pieces round up, and the reason is printed next to the number: a fraction of a carton cannot be bought, and a piece short is a day lost.
Estimates, not quotes
Every output is a planning figure. Your measurements, your supplier's current price sheet, and your contractor's actual quote govern the real order — the calculator just gets the conversation started with numbers instead of adjectives.
How the site itself is engineered
The takeoff engine is half the story. The other half is the set of choices behind the page you are reading — why there is no account, no upload, and no premium tier.
Private by architecture
The entire takeoff engine runs as client-side JavaScript. Your wall dimensions, opening sizes, and prices are computed in your browser tab and never transmitted anywhere — not as a policy we promise to follow, but as a structural fact about how the site is built. There is no account system, no upload step, and no history of your project on our side.
Instant by design
No spinners, no waiting, no 'calculate' button standing between you and the answer. Results update on every keystroke because the math is a handful of multiplications on your own device, and the site is statically built so pages are typically interactive in under two seconds on a normal connection.
Free, ad-supported, labeled
Every feature is free with no usage caps and no email gate in front of a result. Advertising — clearly separated from calculator output and editorial content — pays the hosting bill. There is no premium tier hiding the useful half of the tool behind a subscription.
Independent on purpose
We sell no siding, take no commissions from suppliers, and hold no relationships with manufacturers. The profile presets exist because they answer real questions with real coverage numbers, not because a vendor asked to be listed. When your carton label disagrees with our preset, the label wins and the page says so.
Runs in your browser — nothing to install, nothing sentPhoto: UnsplashHow the guides are written
The calculator is surrounded by guides — on how the takeoff method works, measuring walls and gables, and when accurate estimates matter most. Every one of them answers to the same five rules — and so do we, on this page.
- We show the working — every guide walks through the measurement, the formula, and a worked example, so you can check the math rather than trust it.
- We label uncertainty — where a figure depends on waste assumptions, dye lots, or manufacturer specs, the caveat appears in the same breath as the number.
- We write for the trade and the first-timer — the same page serves a crew lead checking an order and a homeowner holding a tape measure for the first time, and neither gets talked down to.
- We keep tools and text in lockstep — when the calculator changes, the guides around it are reviewed against the new behavior, not left to drift.
- We update, and we date — content is reviewed on a rolling basis, and anything that changes materially gets a fresh look at the examples, not just a typo pass.
Straight answers about the site
Tool-specific questions live in the homepage FAQ. These are the ones about us.
How accurate is the siding calculator?
What is a 'square' of siding, and why does the site use it?
Where do the carton coverage numbers come from?
Why is there a waste factor at all?
Does the calculator include trim, or just the field siding?
Can I use the calculator for materials other than vinyl?
Who is behind the site?
How is the site funded?
Is the site really free?
Can I use the results to place a final order?
Explore the site
Every homepage section and every page that explains, extends, and governs the tool.
Legal: Privacy · Terms · Disclaimer
Now measure something
The calculator is free, instant, and runs entirely in your browser. Add your walls and gables, deduct the openings, set a waste factor and a profile — and get squares, cartons, trim, and a three-way cost split before your coffee cools.
Open the Siding Calculator