Construction Cost Truth Engine
Know what a build should really cost before anyone hands you a number. Shows a realistic range and the reason behind every dollar, then checks a contractor's bid against it.
- Low (P10)
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- High (P90)
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- Per heated sf
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- Budget to carry
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Where the money goes
Each line is its own mini-estimate: quantity × unit rate × location, with its own uncertainty. Whiskers show the P10–P90 spread. Hover a bar for the basis.
Show as table
Biggest levers
Change one input, keep the rest: how much the most likely cost moves. Tap one to apply it.
Prototype. Unit rates are placeholder calibration values meant to be replaced with licensed cost data and local builder surveys. This is an estimate for planning and bid comparison, not a quote or a guarantee.
What-if scenarios
Save any combination of inputs from E-1 and compare them side by side. The three examples below are variations of the sample 2,000 sf home.
Tap Load to send a scenario back to E-1 for editing.
Bid check
Type in the contractor's numbers line by line and each one gets compared to the truth range for your current E-1 inputs. The figures loaded below are a sample bid with some typical problems built in.
The position bar shows where the bid falls within that line's range: the shaded band runs from P10 to P90, the tick marks most likely, and the dot is the bid.
Cost assumptions
Every rate the engine uses is listed here. If your builder, supplier or a recent job says a price is different, change it and every sheet updates. Changed values are highlighted and saved with each project version.
Remodel-only rates (demo, hidden conditions, tear-off extras) use fixed values in this prototype. The full version makes every rate editable and records its source.
Report & scope of work
A truth report you can hand to contractors: the range, the breakdown, and a written scope of work by trade, so every bidder prices the same job. If a bid is entered in E-3, the comparison is included.
Saved projects & versions
Each save keeps a full snapshot: inputs, your custom assumptions, any bid you entered, and the result. When the design changes or a new bid comes in, save again and see how the number moved.
Pricing logic
A square-foot calculator multiplies one number. This engine builds the cost up from the parts of the house, gives every part its own uncertainty, and then adds the markups a contractor adds. That's why it can explain itself and check a bid line by line.
Describe the build
Type, location, size, systems, finish, who builds it.
Measure it
Footprint = area ÷ stories; roof = footprint × 1.2; fixtures from bath count.
Price each part
Rate table per line, by option: CBS $38/sf, metal roof $14.50/sf.
Local reality
Location factor, labor-market premium on the labor share, finish multiplier, sweat equity.
What the GC adds
General conditions 9%, overhead & profit 15% (or owner-builder allowance).
Range, not a guess
Per-line spread combined statistically into P10 / P90.
Truth report
Likely, range, budget with contingency, levers, bid verdicts.
The formula
For each line item i:
Why these choices
- Lines instead of $/sf. A contractor's bid is written in lines, so the estimate has to be too. Otherwise nothing can be compared.
- Skewed ranges. Every line can overrun more than it can underrun: foundations on piles run −22% / +45%, hidden conditions in a remodel −30% / +90%. Real jobs behave like that.
- Statistical combination. Not every line goes over at the same time. Stacking all the worst cases would give a range too wide to be useful, so the spreads are combined by root-sum-square.
- Labor share per line. After a storm, labor gets more expensive and materials don't move as much. Sweat equity only removes labor too.
- Contingency kept separate. The likely number is what it should cost. The budget is what you need to have available.
Live build-up for your current E-1 inputs
From the parts of the house to the budget you need to carry.
Rate table in use
Each rate is a versioned, dated record that can be traced to its source. That record is what makes the number "truth" and not opinion.
User flow & screens
A realistic number in 60 seconds with no sign-up, detail only for people who want it, and bid checking where the money gets made (and where people get protected).
Core screens
1 · Quick scope
Four questions. Sensible defaults fill in everything else, and every default is shown and can be changed.
2 · Truth report
Leads with the range, then the breakdown and the levers. "Refine" opens the system-by-system inputs.
3 · What-if
Side-by-side ranges, plus a plain-language note on which lines caused the difference.
4 · Bid check
A verdict on every line, payment-term red flags, and a list of questions ready to send the contractor.
MVP & business model
V1 has one job: before you sign, know whether the number is fair. Launch in one market (South Florida), win trust with transparent logic, then expand region by region as the cost data is built.
Essential v1 features
All seven now work in this prototype. The sheet column shows where to try each one.
| # | Feature | What it does | Try it |
|---|---|---|---|
| 1 | Guided questionnaire | Plain-language questions, one topic per step, with the estimate updating as you answer | Q-1 |
| 2 | Adjustable cost assumptions | Every unit rate, location factor, finish level and markup can be edited and reset | A-1 |
| 3 | Low / expected / high estimate | P10, most likely and P90, plus the budget to carry with contingency | E-1 |
| 4 | Trade-by-trade breakdown | Each line with its own basis, range and labor share, plus the biggest levers | E-1 |
| 5 | Contractor-bid comparison | A verdict on every line, payment and paperwork checks, questions to ask | E-3 |
| 6 | PDF report & scope of work | Range, breakdown, scope by trade with allowances, and the bid comparison | R-1 |
| 7 | Saved project versions | Full snapshots with notes, showing how the number moved between versions | P-1 |
Build timeline for v1
Later releases
v2 · Read documents
- AI proposal reading: upload a contractor's PDF and have its lines mapped to the estimate automatically
- Drawing takeoffs: quantities (wall length, roof area, window count) read from plans
v3 · Run the job
- Construction schedule: phases and inspections tied to the scope of work
- Payment tracking: each draw checked against work completed, with lien waivers logged
- Change orders tracked against the original budget
v4 · Live prices
- Supplier quotations: request and compare material quotes by line
- Verified final costs from users tighten each line's range
- New regions beyond Florida and the Bahamas
Business model
Your five tiers. Prices marked "suggested" are my starting points to test, not market research.
| Tier | Who it's for | Price | What they get | Notes |
|---|---|---|---|---|
| Free | Anyone | $0 | Basic cost range and top levers | This is the marketing. Keep it free and fast. |
| Homeowner report | Owners, DIYers | $29–$99 / project | Full breakdown, PDF report, scope of work, saved versions | Price by project size, e.g. $29 bath or roof, $59 remodel or addition, $99 new home (suggested) |
| Contractor bid audit | Owners with bids in hand | Premium one-time | Line verdicts, payment-term review, questions to ask, for up to 3 bids | Suggested $149–$299. Adding an optional review by a human estimator justifies the higher price. |
| Professional | Builders, developers | Monthly subscription | Unlimited projects, their own rate tables, branded reports | Good builders use it to back up their prices to clients |
| White-label | Banks, insurers, architects, real-estate firms | Annual license | The engine under their brand | Lenders can check draws, insurers replacement cost, architects early budgets. Needs a proven track record, and the cost-data license must allow redistribution. |
Keep one rule for every tier: contractors never pay for placement or ranking. Independence is what people are paying for.
Where the truth comes from
- Baseline: licensed national cost data (RSMeans or Craftsman) for unit rates and city cost indexes.
- Local calibration: a quarterly survey of South Florida GCs and subs that adjusts each rate.
- Public data: county permit and impact-fee schedules, and BLS regional wages for labor shares.
- The moat: final costs reported by users and checked against invoices. Each one tightens a line's range.
Risks to plan for
- Accuracy: launch in one region, always show the range and the date of the data.
- Liability: label it as an estimate, not a quote. Have a Florida attorney review the terms and the bid-audit wording.
- Stale data: after hurricanes, prices jump. Use the market switch plus quarterly updates.
- Contractor pushback: fair builders gain from transparency. Give them the Pro tier.