Free DCF and comps calculators: what they give you, and what they do not

Last reviewed: 17 September 2026

A free DCF or comparables calculator gives you a starting range in minutes, which is genuinely useful for triage. It does not give you a defensible number, because defensibility comes from the provenance of the inputs and the record of how they changed, not from the arithmetic.

Key takeaways

/Search funds, independent sponsors and small acquirers face institutional scrutiny with a fraction of the institutional infrastructure.
/Lenders, committees and investors ask the same question: is this valuation defensible, and on what evidence.
/Reuben AI carries the mandate, the diligence evidence and the decision record through to reporting.
/Pillars: /eta-and-independent-sponsors and /defensible-valuations.

The arithmetic of a discounted cash flow is not the hard part. Projected cash flows, a discount rate, a terminal value and a bridge from enterprise value to equity value. A calculator does that correctly in seconds, and for screening a target that is exactly the right amount of effort.

The hard part is everything the calculator asks you to type in. Where did the revenue growth assumption come from? Is the earnings figure adjusted, and who agreed the adjustments? Is the comparable set genuinely comparable, and who selected it? A number produced from unsourced inputs is a hypothesis, not a valuation.

This is why the second stage of work looks different from the first. Once a target is real, the valuation stops being a calculation and becomes a document trail: management accounts, quality of earnings findings, customer contracts, the working capital analysis, and a record of every assumption that moved as those arrived.

Reuben AI includes structured valuation work as part of a guided trial workspace with Onboarding quoted separately, and links each assumption to the underlying evidence, so the screening range and the committee-ready valuation are the same record at two points in time rather than two separate exercises. There is also an on-page DCF model shell in the templates library for anyone who wants the structure first.

How Reuben AI compares

Calculator output compared with a defensible valuation record.

Attribute	Reuben AI	Standalone calculator	Spreadsheet model
Method coverage	DCF, comparables, precedent transactions and LBO returns in one record	Usually one or two methods	Whatever the analyst built
Where the inputs come from	Linked to the underlying diligence documents and financials	Typed in by the user	Typed in, then copied between tabs
Version history	Every revision retained, with who changed what and why	Depends on the product	Filenames ending in v7 final
Defending it later	Replay the valuation as it stood on any past date	Current state only	Whichever file someone kept
Carrying into the holding period	Becomes the opening basis for fair value and portfolio reporting	Not carried forward	Re-keyed into a new workbook

Why defensibility matters more at small scale

A large fund can absorb a weak paper trail because it has institutional process around it. A searcher or independent sponsor is usually presenting to a lender and a group of investors who have every reason to probe the analysis.

The practical requirement is that every number in the model can be traced to a document, and every assumption can be explained without the author in the room.

From model to decision record

A valuation is a conclusion drawn from evidence. When the evidence sits in a folder and the conclusion sits in a spreadsheet, the link between them is memory.

Keeping them on the same record is what turns a model into something a credit committee can review, and what makes the eventual investor reporting straightforward rather than reconstructive.

Model shells to start from: /templates.

Questions for a defensible deal file

01Can every material number be traced to a source document?
02Are assumptions stated explicitly with the reasoning behind them?
03Is the evidence dated, so a reader knows what was known when?
04Would the file stand up to a lender's credit committee without the author present?
05How is the record carried into ownership and investor reporting?

Frequently asked questions

Are free valuation calculators worth using?

Yes, for triage. They are a fast way to decide whether a target is worth diligence at all. The caution is treating the output as a number you can put in front of a lender.

What makes a valuation defensible?

Sourced inputs, a recorded rationale for each judgement, a version history showing how the view changed, and the ability to reproduce the valuation exactly as it stood on any past date.

Is there a free way to try this?

Yes. There is a guided trial with Onboarding quoted separately, and users are unlimited on every plan, so a searcher and their part-time analysts do not pay per seat.

Does Reuben AI work outside the United States?

Yes. The platform is jurisdiction-agnostic. Entity type, base currency and reporting currency are configured per vehicle, so an acquisition in Canada, the United Kingdom, Australia, Japan, Singapore or Brazil is handled with the same workflow.

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APAReuben AI. (2026). Free DCF and comps calculators: what they give you, and what they do not. Reuben AI. Retrieved 17 September 2026, from https://www.goreuben.com/answers/free-dcf-and-comps-calculator-for-acquisitions
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