See risk before you quote
Explore a distribution of modeled costs and finish dates. See how often your proposed bid loses money under your assumptions.
Monte Carlo estimating for fixed-price projects
See the cost risk
See the cost risk
before you quote.
For consultants, agencies and engineering teams quoting fixed-price work. Test how uncertain costs affect your margin, then model tasks, risks and deadlines in the licensed browser app.
The calculator is free; no account or license needed. Start with its editable example. The full app requires a one-time license from $129 and an online license check. Compare license rights and prices →
BidVariance / decision previewIllustrative example
A fixed-price integration project
One estimate. A range of outcomes.
Start with ranges, not a single best guess.
| Work package | Low | Likely | High |
|---|---|---|---|
| Discovery | 4 | 6 | 9 |
| Integration | 15 | 22.5 | 40 |
| Testing & handover | 6 | 9 | 15 |
Three independent effort ranges, one daily cost rate. Follow these same inputs through 4,000 sampled outcomes to a selling price.
Read the range of possible total costs.
- P50 cost
- $31,630
- P80 cost
- $35,114
- P90 cost
- $37,051
P80 means at least 80% of these sampled costs fall at or below $35,114. The chart and price use the task ranges shown in step 1.
Choose a modeled confidence for your margin.
Cost confidence
Quote at P80 · 20% target margin$43,893$35,114 ÷ (1 − 20%), rounded up
This price targets at least 20% margin in 80% of the sampled cost outcomes. Effort is not elapsed time; check deadline confidence separately.
Explore the steps, then try P50, P80 or P90 to compare sample prices.
Step 1 of 3Interactive example
Illustrative sample · Beta-PERT · fixed seed · no overhead or risk events. How the model works →
Software consultancies
Systems integrators
Engineering firms
Agencies & studios
Specialist contractors
01 See the downside before you sign.
Compare price against your margin target
Compare your price with the amount needed to support your target margin. Make the tradeoff between price and risk visible.
Stay in control, locally
Build and run your model on your device. Export a project backup to keep a copy, or transfer your estimate to another browser.
02 From estimate to decision in four steps.
Build your estimate
Add tasks and risks. Define optimistic, likely, and pessimistic values per work package.
Run simulations
Explore thousands of possible outcomes, with your task ranges, dependencies and risk events included.
Understand the risk
Read P50 / P80 / P90 cost and schedule, probability of loss, and the drivers that move the tail.
Review the decision against your rules
Inspect the bid / no-bid label at your thresholds and the quote implied by your assumptions. Review the inputs before committing.
A better conversation about risk
The number matters.
The number matters.
The assumptions matter more.
A precise-looking quote can hide an uncertain plan. Bring the cost range, margin target and deadline into the same decision.
Explore the methodology →What price supports our margin?
Read the minimum quote at your chosen confidence level. Keep margin and markup separate.
How likely is this deadline?
Model task dependencies and schedule uncertainty alongside the cost of the work.
Which assumption should we challenge?
Review the tasks driving cost variation. Refine the scope or estimate, then run the model again.
03 Build a more defensible estimate.
Product guide
Your first project, step by step
From a task range to a simulation you can interpret.
14 free calculatorsAnswer one question now
Check margins, discounts, scope changes, risk, capacity and cash flow.
Field notesGet beyond the best guess
Practical explanations of fixed-price bidding and project uncertainty.
Follow a practical estimating guide · Search the resource library · Look up an estimating term
Latest field notes
All notes →-
Rush fees: price the schedule, not the urgency
A rush plan has its own hours, helper cost and risk. Price the compressed schedule from those inputs, then test a flat surcharge against the cost floor.
-
Rate increases: how many hours can you lose?
A 15% rate rise can still leave an existing client worth more, even after it buys fewer hours. Two break-even tests show how far the hours can fall.
-
Three-point estimates: ranges before guesses
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.
Choose by how you work
One engine. The right license for your work.
Every license includes the simulation engine, all simulation depths and printable reports. Start with who will use it, and whose projects you analyze.
Projects stay local; these licenses do not include a shared cloud workspace. Compare prices and full license rights →
Recommended reading
How to Remain Valuable When Intelligence Becomes Cheap
Estimates, drafts, and analysis are getting cheap to generate. Knowing which estimate to trust, what to charge for it, and which bid to walk away from is the durable skill — and the subject of this short ebook.
- Length
- 224 pages
- Formats
- PDF + EPUB, via Gumroad
- Price
- $3.84 one-time
- For
- Estimators, consultants & firm owners
04 A few things to know before you start.
Do I need to understand Monte Carlo simulation?
You can start with a low, likely and high estimate for each task. The app samples those ranges to show possible costs and schedules. The important part is making your assumptions realistic. Start with a free project estimate template, follow the first-project guide, or try a single-task PERT estimate first.
Can I try something before buying a license?
Yes. Adjust an example bid calculation without an account, or explore the other free estimating calculators. The walkthrough above is an illustrative project with sampled results. The full simulation workspace requires a license key delivered through Gumroad. Compare the available licenses.
Do these probabilities predict the project outcome?
They describe outcomes under the estimates and model you supply. Missing costs, unrealistic task ranges or unmodeled risks can make a precise result misleading. The model does not allocate constrained staff or replace a contract review. Inspect the method and limitations before making a commitment.
What do I need to run the app?
Use a browser with JavaScript, Web Workers and IndexedDB enabled. The full workspace needs an online license check when you open it; projects are stored in this browser, with no automatic cloud backup. Try the free calculator on your device and read the storage and offline guidance before buying.
How do I move a project to another device?
Export a project backup from the app, save the file somewhere you control, and import it in the other browser. Local projects do not automatically sync between devices. Read the backup and transfer guidance.
Where can I ask a product or licensing question?
Use the developer contact. Describe what you were trying to do and which browser you use. Keep full license keys, payment details and confidential project files out of your initial message.
Not ready for the full engine? Start with a free tool — PERT calculator · deadline confidence · minimum bid price