Excel vs Adlega: When a SaaS Financial Model Outgrows the Spreadsheet (2026)

For a SaaS founder, Excel or Google Sheets wins on cost, flexibility and familiarity: a sheet can model any deal you can describe, costs nothing extra if you already have it, and is the format most investors and analysts expect to open. It starts to break when the model grows: copies of the file for each scenario drift apart, the MRR waterfall (new, expansion, contraction and churned revenue by cohort) is hundreds of hand-dragged formulas, and formula errors are normal rather than rare, with field audits in Raymond Panko's research finding errors in 91% of the spreadsheets examined from 1997 on. Adlega is SaaS-native modelling software with the MRR logic built in, scenarios inside one model and an AI CFO; it has a free plan and paid plans from $49 a month, but it is less flexible than a blank sheet and exports CSV rather than a live Excel workbook. If your model is still simple, stay in Excel and start from our free Excel templates.

Excel vs Adlega at a glance

Adlega plans and features from the Adlega pricing section and help center, read October 22, 2026. We do not quote Microsoft or Google prices here because most founders already pay for one of them.

Where spreadsheets win

• Cost. If you already pay for Microsoft 365 or Google Workspace, a model costs your time and nothing else.
• Flexibility. A hardware add-on, a services line with milestone billing, a revenue share with a partner, a debt facility with an odd covenant: a sheet takes all of it. Any modelling tool, Adlega included, makes you fit its structure.
• Investor familiarity. An associate who wants to test your churn assumption will ask for the workbook, change one cell and watch what happens. A spreadsheet is the format that conversation assumes.
• Ownership. The file is yours, works offline and outlives any vendor; Finmark's shutdown is a reminder that tools can disappear (see our Finmark alternative page).

If those four matter most to you, stay in a spreadsheet. Our free SaaS finance templates are Excel downloads with no email: an MRR forecast, ARR waterfall, burn and runway, a budget and rolling forecast, hiring plan, scenario planning and more, each next to a live calculator that checks the same math.

Where spreadsheets break

Version control

Google Sheets and Excel on OneDrive keep version history, so "which file is current" is less of a problem than it was. The problem that remains is copies made on purpose: the version sent to the lead investor, the board copy, the one the new finance hire rebuilt. Each one is a fork, and nothing tells you which numbers changed between them.

MRR waterfall logic

A SaaS model that investors trust shows where MRR comes from each month: new, expansion, contraction and churn, ideally by the month each customer cohort started (more on that in cohort analysis). With monthly cohorts over 36 months, that is a triangle of 666 cells for each metric you track, every one a formula that refers to the cohort's age. Insert a month, shift a start date or change how churn applies and the triangle has to be redragged. This is where most hand-built SaaS models quietly go wrong, and it is the part Adlega computes for you (see MRR and NRR for the definitions).

Scenario copies

The common way to build a downside case is to copy the tab and change the inputs. Then you fix a formula in the base case, and the downside tab still has the old one. Two weeks later the two cases differ for a reason nobody remembers. The cleaner spreadsheet pattern is one set of formulas with a scenario switch on the inputs, which works but takes discipline to keep. Our scenario planning guide covers both approaches.

Formula errors

The most cited primary research on spreadsheet errors is Raymond Panko's at the University of Hawaii. In "Spreadsheet Errors: What We Know. What We Think We Can Do" (EuSpRIG proceedings, 2000), he collects seven field audits of real organisational spreadsheets:

• Across all seven audits, 24% of 367 spreadsheets had errors, but the older audits mostly counted only serious errors with methods "not likely to catch a majority of errors".
• The audits from 1997 on, with better methods, found errors in 91% of 54 spreadsheets.
• Audits that measured it found 0.4% to 2.5% of cells holding an original error. In laboratory experiments with about a thousand subjects, 51% of spreadsheets had errors, even though most were only 25 to 50 cells.

A later paper by Panko and Nicholas Ordway, "Sarbanes-Oxley: What About all the Spreadsheets?" (written in 2005), summarises audits that found errors in 94% of spreadsheets and, where errors were counted per formula, errors in 5.2% of formulas. Its conclusion: "Most large spreadsheets have thousands of formula cells, so most large spreadsheets probably have dozens or even hundreds of errors."

Two cautions. These audits ran between 1987 and 2004 and were mostly of corporate spreadsheets, not startup models. And the point is not that founders are careless: Panko's argument is that human error rates in complex cognitive tasks run about 2% to 5%, so a large hand-built model will contain some. Applied to the cohort triangle above, 0.4% to 2% of 666 cells is roughly 3 to 13 wrong cells per metric (our arithmetic on his rates, not a measured figure).

Where Adlega fits better

Adlega is built for one job: a 36-month operating model for a SaaS company. You describe pricing plans, the funnel, churn, headcount and expenses; it builds revenue cohort by cohort into the MRR waterfall, then the P&L, cash flow, runway and unit economics (CAC, LTV, LTV:CAC, CAC payback). Change one assumption and every statement updates. What-if mode tests churn, marketing spend or pricing against your baseline without touching the real model, and goal seek works backwards from a target. The AI CFO answers finance questions from your own numbers and shows which drivers and formulas produced a figure, which is the "trace precedents" job done in plain language. The free plan covers one model; Founder ($49 a month, $41 billed yearly) adds up to 3 models, multiple editable scenarios and one actuals-sync integration.

Where Excel is still the better choice

Stay in a spreadsheet if your revenue does not look like SaaS (hardware, marketplace take rates, project fees), if an investor or banker needs a workbook they can rework, or if you enjoy building the model and have the time to maintain it. Adlega exports the full 36-month forecast to CSV, which opens in Excel or Google Sheets, but that export is a static snapshot, not a formula workbook. It also does not import an existing spreadsheet model: you can enter past months of revenue, customers and expenses as actuals, but the assumptions are rebuilt in Adlega.

Many founders end up with both: the operating model in a tool, and a spreadsheet for one-off analysis built on the exported numbers.

Signs you have outgrown the spreadsheet

• You keep more than one copy of the model and are not sure they agree.
• Your MRR does not reconcile to the sum of new, expansion and churned MRR.
• Changing one hire date or price takes an hour because it touches several tabs.
• Only one person can safely edit the file.
• Before an investor call, you rebuild a chart instead of checking an assumption.

FAQ

Can I build a SaaS financial model in Excel?

Yes, and many good ones are. Start from a template rather than a blank sheet: ours are free Excel downloads, no email, on the templates page. The parts that take the most care are the cohort-based MRR waterfall and keeping scenarios on one set of formulas.

Is Google Sheets good enough for financial modeling?

For an early-stage SaaS model, yes. Sheets has shared editing and version history built in; Excel handles very large workbooks and offline work better. The modelling problems on this page apply to both.

Do investors want the financial model in Excel?

Many ask for a workbook so they can test assumptions, especially at a priced round. A read-only link or a CSV export answers "what are the numbers"; a workbook answers "what happens if I change this". Know which one your investor wants.

How common are spreadsheet errors?

Very common in the research. Panko's 2000 review found errors in 91% of 54 spreadsheets in field audits from 1997 on, and a 2005 paper with Ordway reports errors in 5.2% of formulas where they were counted. Those audits are old and were mostly of corporate spreadsheets, but no study we know of shows the rate has fallen.

Can Adlega export to Excel?

It exports the complete 36-month forecast to CSV, which opens in Excel or Google Sheets. The export is a static copy; it does not update when you change the model.

What is the best Excel alternative for a startup financial model?

It depends on what you want to stop doing. If you want SaaS logic built in and do the work yourself, a self-serve tool like Adlega. If you want someone else to build it, a service like Forecastr. The field is compared in best SaaS financial modeling software; business-plan tools are covered in LivePlan vs Upmetrics vs Brixx for SaaS.

Related: how to build a SaaS financial model, the SaaS financial model template guide, what happened to Causal's templates, and what an AI CFO does.

Where Adlega is weaker

Adlega is self-serve: you build the model yourself. The AI CFO guides you and explains every number, but no analyst builds it for you, so a founder who wants the work done by a person may prefer a done-for-you service. Its integrations (Stripe, Chargebee, Google Analytics, Google Ads), forecast-vs-actuals and scenario comparison are still rolling out on the Growth plan, so today most numbers come from the drivers you enter rather than synced data. And it is built around SaaS metrics, so a business without recurring revenue will get less from it than from a general-purpose planning tool.