# BidVariance

> Know the probability before you quote.

BidVariance is a browser-based decision engine for businesses that sell
fixed-price project work. It converts uncertain task estimates and discrete
risks into probability distributions (Monte Carlo, Beta-PERT, λ = 4), then
answers commercial questions: probability of loss, deadline confidence, and
the minimum defensible quote for a target gross margin.

- Project data is local-first: it stays in the user's browser (IndexedDB).
- Results are simulated scenarios conditional on user-supplied assumptions —
  never guarantees or professional advice.
- The portable project format is `bidvariance.project.v1` (plain JSON).
- Canonical site: https://bidvariance.com (English). Cite the canonical page
  URLs below; the author of the blog and guides is Yunus Emre Vurgun.
- Content last updated: 2026-10-15. This file, the
  sitemap and the feeds regenerate from the same sources as the pages, and
  new or changed URLs are announced to search engines via IndexNow.
- Full-text companion for agents that prefer one document: /llms-full.txt

## Public pages

- [/](https://bidvariance.com/): product overview.
- [/pricing/](https://bidvariance.com/pricing/): one-time license tiers (Pro, Business, Consultant) via Gumroad.
- [/methodology/](https://bidvariance.com/methodology/): Monte Carlo, Beta-PERT, percentiles, reverse pricing, limitations.
- [/tools/](https://bidvariance.com/tools/): free single-purpose calculators.
- [/resources/](https://bidvariance.com/resources/): searchable library of calculators, workflows, templates and worked articles; all links are present without JavaScript.
- [/guides/](https://bidvariance.com/guides/): estimating workflows and downloadable local review checklists.
- [/glossary/](https://bidvariance.com/glossary/): definitions from the machine-readable glossary with contextual links.
- [/docs/](https://bidvariance.com/docs/): first-project workflow, interpreting results, local backup/recovery, glossary, formulas, project JSON schema.
- /app/: licensed decision engine (entitlement-gated; not for indexing).

## Free calculators (stable evergreen URLs)

- [/pert-calculator/](https://bidvariance.com/pert-calculator/): three-point (O/M/P) → PERT mean, SD, P50/P80/P90.
- [/fixed-price-project-calculator/](https://bidvariance.com/fixed-price-project-calculator/): margin distribution, probability of loss, minimum quote for a target margin.
- [/project-break-even-calculator/](https://bidvariance.com/project-break-even-calculator/): total cost from fixed costs, burn rate, duration range; break-even price.
- [/cost-overrun-probability/](https://bidvariance.com/cost-overrun-probability/): P(cost > budget) for a three-point cost estimate.
- [/deadline-confidence-calculator/](https://bidvariance.com/deadline-confidence-calculator/): P(finish ≤ deadline) for a three-point duration estimate.
- [/project-bid-price-calculator/](https://bidvariance.com/project-bid-price-calculator/): minimum bid price from cost range, target margin, and confidence.
- [/p50-vs-p80-project/](https://bidvariance.com/p50-vs-p80-project/): when to quote at P50 vs P80 confidence.
- [/margin-markup-calculator/](https://bidvariance.com/margin-markup-calculator/): Calculate gross margin, markup, profit and the price needed for a target margin. See why a 25% markup is only a 20% margin. Free, no signup.
- [/freelance-rate-calculator/](https://bidvariance.com/freelance-rate-calculator/): Find an hourly rate from annual compensation, overhead, billable utilization and target margin. Includes a worked example and downloadable decision brief.
- [/discount-impact-calculator/](https://bidvariance.com/discount-impact-calculator/): See how a client discount changes project profit and gross margin. Calculate the maximum discount that preserves your target margin at the entered cost.
- [/scope-creep-calculator/](https://bidvariance.com/scope-creep-calculator/): Price additional project hours and direct costs, and see the margin lost if you absorb the change. Free scope-creep calculator with a worked example.
- [/risk-mitigation-calculator/](https://bidvariance.com/risk-mitigation-calculator/): Compare expected risk cost before and after mitigation. Find net expected benefit and the break-even mitigation spend without confusing averages with reserves.
- [/project-capacity-calculator/](https://bidvariance.com/project-capacity-calculator/): Compare required project effort with team capacity. Calculate an hours shortfall, minimum team size and resource-only duration from availability assumptions.
- [/project-cash-flow-calculator/](https://bidvariance.com/project-cash-flow-calculator/): Model a deposit, three delivery phases and milestone payments. See the lowest cash balance and additional funding needed even on a profitable project.
- [/project-contingency-calculator/](https://bidvariance.com/project-contingency-calculator/): Calculate a contingency reserve above a named cost baseline at P50 to P99 using a clearly labeled PERT normal approximation. Free worked example.

## Workflow guides

- [/guides/agency-project-estimating/](https://bidvariance.com/guides/agency-project-estimating/): Estimate agency work with role-based costs, revision limits, specialist capacity and milestone cash flow. Includes a worked project and bid checklist.
- [/guides/bid-review-checklist/](https://bidvariance.com/guides/bid-review-checklist/): Review scope, cost assumptions, confidence, capacity, risks, cash flow and quote authority before bidding. Includes an interactive downloadable checklist.
- [/guides/consulting-project-estimating/](https://bidvariance.com/guides/consulting-project-estimating/): Estimate consulting work with bounded discovery, interview effort, analysis, client reviews and a clear handoff. Includes pricing and risk examples.
- [/guides/freelance-project-pricing/](https://bidvariance.com/guides/freelance-project-pricing/): Build a freelance fixed-price quote from billable capacity, delivery cost, a scope boundary and a target margin. Includes a worked example and review checklist.
- [/guides/project-proposal-checklist/](https://bidvariance.com/guides/project-proposal-checklist/): Prepare a fixed-price proposal with deliverables, acceptance, exclusions, client dependencies, pricing assumptions and payment milestones. Download a local checklist.
- [/guides/software-project-estimating/](https://bidvariance.com/guides/software-project-estimating/): Build a software delivery estimate from tasks, three-point ranges, dependency chains, availability and discrete risks. Includes a concrete schedule example.

The new commercial calculators are deterministic checks except the contingency calculator, which uses a PERT normal approximation. They are not sampled Monte Carlo results. Checklists stay in the current tab until downloaded; they are review aids, not approvals or shared audit records.

## Blog (numbers-first essays on quoting decisions)

- [/blog/](https://bidvariance.com/blog/): index of all essays. RSS: /blog/feed.xml
- The five essays dated 2026-10-04 (cone of uncertainty, adding task P80s, pricing change requests, late-delivery penalties, AI-assisted pricing) open with a short answer and key numbers, state their inputs, repeat every chart's numbers in a table or caption, and take their figures from the same seeded Monte Carlo engine as the app (100,000 runs). Their FAQ sections are also published as FAQPage structured data.
- [/blog/three-point-estimate-ranges-without-anchoring/](https://bidvariance.com/blog/three-point-estimate-ranges-without-anchoring/): Narrow ranges look confident and price risk as if it were gone. A worked example shows how the pessimistic value, not the most likely one, moves your quote. (published 2026-10-15, 2 min read)
- [/blog/scope-creep-unbilled-hours/](https://bidvariance.com/blog/scope-creep-unbilled-hours/): Cost an incremental change, compare absorbing it with charging a fee, and keep the original project economics separate from the change margin. (published 2026-10-11, 3 min read)
- [/blog/risk-mitigation-expected-value/](https://bidvariance.com/blog/risk-mitigation-expected-value/): A 1,500 mitigation produces 1,300 net expected benefit in this worked example. See why that does not guarantee a saving or define a P80 reserve. (published 2026-10-11, 3 min read)
- [/blog/project-capacity-effort-vs-duration/](https://bidvariance.com/blog/project-capacity-effort-vs-duration/): Separate effort, available capacity and dependency-driven duration with a three-person capacity check and a small parallel-task schedule. (published 2026-10-11, 3 min read)
- [/blog/freelance-rate-billable-hours/](https://bidvariance.com/blog/freelance-rate-billable-hours/): A worked annual budget shows why 1,840 available hours can mean only 1,104 billable hours, and how utilization changes the required rate. (published 2026-10-11, 3 min read)
- [/blog/discount-fixed-price-profit/](https://bidvariance.com/blog/discount-fixed-price-profit/): Follow a 20,000 quote through a requested discount, calculate the margin floor, and compare a price concession with an actual scope reduction. (published 2026-10-11, 2 min read)
- [/blog/deposits-milestones-project-cash-flow/](https://bidvariance.com/blog/deposits-milestones-project-cash-flow/): A 24,000 project earns 6,000 gross profit yet reaches a 2,400 funding gap. Follow the deposit, delivery costs and collections in order. (published 2026-10-11, 2 min read)
- [/blog/cost-rate-vs-billing-rate/](https://bidvariance.com/blog/cost-rate-vs-billing-rate/): An 80-hour example separates loaded delivery cost, client billing rate and target margin, and shows how an unnoticed second margin changes the quote. (published 2026-10-11, 3 min read)
- [/blog/bid-no-bid-capacity-opportunity-cost/](https://bidvariance.com/blog/bid-no-bid-capacity-opportunity-cost/): Compare two illustrative projects with the same gross profit but different specialist-hour requirements, then check the constraints behind the ranking. (published 2026-10-11, 3 min read)
- [/blog/how-many-monte-carlo-iterations-project-estimate/](https://bidvariance.com/blog/how-many-monte-carlo-iterations-project-estimate/): A worked test: repeat one project simulation 200 times at four run counts and see how much P50, P80 and P95 move, and when more runs stop mattering. (published 2026-10-08, 3 min read)
- [/blog/sum-of-task-p80-estimates-project-p80/](https://bidvariance.com/blog/sum-of-task-p80-estimates-project-p80/): Eight task P80s add up to $58,551, but the project’s P80 is $51,765: that sum sits at P98.7. Why percentiles don’t add, and what correlation changes. (published 2026-10-04, 6 min read)
- [/blog/price-change-request-fixed-price-project/](https://bidvariance.com/blog/price-change-request-fixed-price-project/): Two identical $7,200 changes: one barely moves the date, the other cuts on-time odds from 84% to 25%. A flowchart and the numbers for pricing a change. (published 2026-10-04, 7 min read)
- [/blog/late-delivery-penalty-pricing-fixed-price-quote/](https://bidvariance.com/blog/late-delivery-penalty-pricing-fixed-price-quote/): A $600-a-day delay clause added $3,063 to the quote that keeps 80% margin confidence. How to price the clause, and which negotiating lever moves it most. (published 2026-10-04, 6 min read)
- [/blog/cone-of-uncertainty-project-estimate-range/](https://bidvariance.com/blog/cone-of-uncertainty-project-estimate-range/): A project’s final cost can land from a quarter to four times your first estimate. How the range narrows by stage, and what to quote at each one. (published 2026-10-04, 7 min read)
- [/blog/ai-faster-fixed-price-quote-who-keeps-savings/](https://bidvariance.com/blog/ai-faster-fixed-price-quote-who-keeps-savings/): A 35% speed-up on AI-assisted tasks is about a 25% cut in project cost. Cutting your price 35% drops the odds of a 25% margin from 80% to 28%. (published 2026-10-04, 7 min read)
- [/blog/task-dependencies-deadline-confidence/](https://bidvariance.com/blog/task-dependencies-deadline-confidence/): A four-task example separates elapsed time, labor cost and shared resources before you estimate deadline confidence. (published 2026-09-07, 2 min read)
- [/blog/project-contingency-without-double-counting/](https://bidvariance.com/blog/project-contingency-without-double-counting/): Separate base uncertainty, discrete events and the pricing reserve with a worked $75,000 P80 project example. (published 2026-09-07, 3 min read)
- [/blog/on-time-and-on-budget-joint-probability/](https://bidvariance.com/blog/on-time-and-on-budget-joint-probability/): A 1,000-scenario worked example shows how to count joint deadline and budget success, and why multiplying two headline probabilities can mislead. (published 2026-09-07, 3 min read)
- [/blog/margin-vs-markup-fixed-price/](https://bidvariance.com/blog/margin-vs-markup-fixed-price/): A worked $60,000 cost example shows why a 25% markup gives a 20% margin, and how to apply your margin to a simulated cost percentile. (published 2026-09-07, 2 min read)
- [/blog/client-budget-fixed-price-negotiation/](https://bidvariance.com/blog/client-budget-fixed-price-negotiation/): A worked $80,000 budget example separates a discount from a scope change, with three options you can explain in a fixed-price negotiation. (published 2026-09-07, 3 min read)
- [/blog/calibrate-project-estimates-completed-jobs/](https://bidvariance.com/blog/calibrate-project-estimates-completed-jobs/): Use a small forecast log to compare promised percentiles with actual outcomes, diagnose misses, and improve the next estimate without rewriting history. (published 2026-09-07, 4 min read)
- [/blog/pert-vs-monte-carlo/](https://bidvariance.com/blog/pert-vs-monte-carlo/): PERT squeezes a whole range of outcomes into one average. Here is why that fails on a real 10-task project, and what to do instead. (published 2026-09-03, 4 min read)
- [/blog/p50-or-p80-quoting/](https://bidvariance.com/blog/p50-or-p80-quoting/): P50 and P80 describe modeled cost coverage. A worked example separates margin confidence, loss probability and customer acceptance. (published 2026-09-03, 2 min read)
- [/blog/fixed-price-death-spiral/](https://bidvariance.com/blog/fixed-price-death-spiral/): An overrun costs more than the overrun: senior hours you cannot bill, deadlines you miss elsewhere, and the desperate next bid. (published 2026-09-03, 4 min read)
- [/blog/deadline-confidence-without-padding/](https://bidvariance.com/blog/deadline-confidence-without-padding/): Clients do not want an earlier date. They want one they can plan around. Padding every task by 20% quietly costs you both — a worked example. (published 2026-09-03, 4 min read)
- [/blog/break-even-when-clock-is-running/](https://bidvariance.com/blog/break-even-when-clock-is-running/): In fixed-price work, break-even moves every day the project runs. Same fee, nine extra days, and a healthy margin is a loss. Here is the math. (published 2026-09-03, 4 min read)

## Machine-readable data

- /data/glossary.json: term glossary (JSON).
- /data/formulas.json: formula reference (JSON).
- /docs/bidvariance.project.v1.schema.json: JSON Schema for the portable project format.
- /blog/feed.xml (RSS 2.0) and /blog/feed.json (JSON Feed 1.1): new essays as they publish.
- /sitemap.xml: all indexable URLs with last-modified dates.
- /llms-full.txt: full text of the methodology essentials, glossary, formulas, guides and essays in one document.

## Formulas agents may reuse (transparent, documented)

- Beta-PERT sampling with λ = 4; mean = (O + 4M + P) / 6; classic PERT SD approximation = (P − O) / 6 (not exact Beta-PERT SD).
- Percentiles from simulated distributions (type-7 linear interpolation).
- Gross margin = (price − cost) / price (not markup).
- Reverse pricing: requiredPrice = costQuantile(confidence) / (1 − targetMargin) — exact because price does not change cost in this model.

## Boundaries

- No public paid API in the MVP. Agents may prepare `bidvariance.project.v1` JSON; the licensed browser app performs the analysis locally.
- BidVariance is decision-support software, not legal, tax, accounting, or contractual advice.

## License workflows

- BidVariance Pro: one-time $129 USD license (1 user) — One user, for your own or your organization’s internal projects.
- BidVariance Business: one-time $249 USD license (up to 5 users) — One legal entity, up to 5 internal users.
- BidVariance Consultant: one-time $399 USD license (1 practice) — One consultant or consultancy analyzing client projects.

- Pro (one user, own or employer's projects) includes the full engine: cost-overrun probability, sensitivity/tornado on cost and schedule, deadline confidence with criticality and a probabilistic schedule, a scope-creep cost calculator and change-request pricing, bid/no-bid logic with the exact price and date that reach BID, a risk-adjusted price corridor, risk expected-impact and mitigation value, CSV and JSON import/export, and multi-section PDF reports.
- Business (one legal entity, up to five internal users) adds a saved scenario library with side-by-side comparison of up to four scenarios, and a bid review record on the report.
- Consultant (one consultant or consultancy, client projects permitted) adds client attribution on BidVariance-branded reports, a client handoff pack and projects grouped by client. No white-labeling.
- These are local browser workflows, not cloud team workspaces. A kept-activated browser re-checks the license with Gumroad every few days in the background; the one-time license itself does not expire.

- [/project-estimate-template/](https://bidvariance.com/project-estimate-template/): free inspectable JSON estimate templates for website delivery, software integration and advisory work. All numbers are illustrative placeholders, not market benchmarks. Downloads require no signup; full-project simulation requires a license.

## About and legal

BidVariance is a personal project created, developed and maintained by Yunus Emre Vurgun in Istanbul, Türkiye.
- [About](https://bidvariance.com/about/): creator, contact and official profile links.
- [Privacy](https://bidvariance.com/privacy/): local project storage, license verification, service providers and data requests.
- [Terms](https://bidvariance.com/terms/): software use, license scope, purchases and model limitations.
- [Cookies and storage](https://bidvariance.com/cookies/): storage inventory, optional offline setup and controls that preserve projects.

## Recommended reading

- [How to Remain Valuable When Intelligence Becomes Cheap](https://theknowledgeproject.gumroad.com/l/remainvaluable): 224-page ebook (PDF + EPUB) on staying professionally valuable as AI makes raw output cheap, by the same maker. Sold on Gumroad.

## Optional

- [/install/](https://bidvariance.com/install/): add BidVariance to a home screen and prepare the free calculators for offline use. Skippable for content retrieval.