Guesstimate
Guesstimate: A free, open-source web canvas for uncertainty modeling and Monte Carlo analysis. Ranked #31 of 32 in Financial Modeling Software by our editors (6.1/10); pricing: Free plan; best for users exploring uncertainty and Monte Carlo models.
At a glance
- Editor score6.1 / 10
- PricingFree plan
- Best forUsers exploring uncertainty and Monte Carlo models
- Free planYes
- Facts checked22 Sep 2026
Where it wins
- Free open-source web canvas with unlimited public models
- Monte Carlo simulation with 5,000 samples per stochastic expression
- Includes sensitivity analysis and financial functions such as NPV and WACC
Where it doesn't
- Web-only platform
- No verified accounting integrations
- Does not provide standard three-statement modeling
Our verdict on Guesstimate
Guesstimate is a web-based spreadsheet for modeling and forecasting uncertain quantities. It is designed for users who need to express assumptions as point values, ranges, proportions, datasets, and formulas, then examine how uncertainty affects results. Its model canvas uses linked cells and supports calculators built from model inputs and outputs. The product is particularly suited to cost estimation, forecasting, and exploratory financial analysis in small companies or other settings where uncertainty is central.
The Free plan provides unlimited public models, while the broader feature set includes public, private, and private organizational models and public model sharing. Guesstimate's open-source approach and web delivery make it accessible for building models without a traditional desktop spreadsheet workflow. Financial functions include NPV, ROI, CAGR, and WACC. For uncertainty analysis, Monte Carlo simulation produces distributions and confidence intervals, with up to 5,000 samples per stochastic expression. Sensitivity analysis helps evaluate how inputs affect outputs.
Guesstimate is a focused choice for exploring uncertain quantities rather than a conventional accounting or corporate-finance modeling suite. It does not offer verified accounting integrations or standard three-statement modeling, so teams that need connected accounting data or integrated income statement, balance sheet, and cash flow models should choose an alternative. Users who value linked formulas, uncertainty inputs, scenario exploration, and financial calculations should find the scope well aligned with those needs. Its fit is strongest when the model's purpose is understanding ranges and probability distributions, not maintaining a full accounting representation of a business.
Guesstimate pricing
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Guesstimate fact sheet
| Free plan | Yes |
|---|---|
| Paid from | Not verified |
| Three-statement modeling | Not verified |
| Valuation models | Not verified |
| Scenario analysis | Not verified |
| Excel add-in | Not verified |
| Accounting data import | Not verified |
| Audit trail | Not verified |
| Supported platforms | web |
| Deployment | Cloud |
| Platforms | Web |
| Support | Email, Live chat, Community, Docs |
| Built for | Small business (editorial estimate) |
| Pricing | Free plan (source) |
| Website | getguesstimate.com |
| Facts checked | 22 Sep 2026 |
Alternatives to Guesstimate
- Financial Modelling ProA budget-friendly web modeler with three-statement projections and deal-focused analysis.9.4
- UniflowBroad startup planning with a free tier and five-year modeling from $25/month.9.2
- BrixxA focused web platform for connected forecasts, scenarios, and financial reporting.9.0
See all Guesstimate alternatives →
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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
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