Strategic decision tool

Build vs. Buy
SaaS calculator

This tool is designed for customers evaluating a SaaS purchase or renewal and wanting to assess the feasibility and long-term total cost of ownership of building the capability in-house.

Adjust the parameters below to model your total cost of ownership and get a strategic recommendation.

Application being evaluated

5 mo away
How long do you expect this solution to remain in active use? Longer lifespans increase total SaaS spend and can shift buy economics.
3 yrs
1 yr5 yrs
Higher criticality increases required quality and resilience.
3 / 5
15
How much does this app need to be tailored to your specific business?
3 / 5
15
How differentiating is this app to your business?
3.0 - High Business Logic
1.05.0

Parameters

Buy

$
$

Annual SaaS Cost Total: $100K

compounded over lifespan
%
one-time
$

Build

10% primary70% / 30%90% primary

Output tokens cost 3–5× more than input. Generation-heavy workloads increase token spend significantly.

Model Stack
coeff 0.99 · 1.00× output
$137K
3-yr est.
Higher appetite means faster AI-assisted build velocity.
3 / 5
15
Planned implementation window for proprietary build.
6 months
1 mo2 yrs
$300K/yr total
$

Count · cost per engineer / year

$

Count · cost per rep / year

Build vs Buy Comparison

Side-by-side 3-year TCO comparison for vendor purchase vs proprietary build.

Vendor (Buy)
$463K

Includes license, implementation, and support-linked SaaS spend.

Proprietary (Build)
$409K

Includes development, maintenance, and ongoing support costs.

Loading chart…
3-Year Savings
$54K
Recommended option: Proprietary (Build)

Build estimate assumes 5x velocity via Vibe Coding.

Optional: save scenario & generate report

Saves your inputs and produces a summary analysis. Add your email if you want a copy in your inbox.

Session ID: —

Build vs. buy SaaS: common questions

Quick answers to the questions behind every build-or-buy software decision.

Should I build or buy my SaaS?

It depends on the total cost of ownership over the software’s lifespan, how differentiating the capability is, how fast you need it, and your team’s build velocity. Commodity needs usually favor buying vendor SaaS; differentiating, long-lived capabilities can favor building. The calculator above compares the TCO of both paths over your expected app lifespan (1–5 years) so you decide with numbers rather than instinct.

Should I vibe code my SaaS instead of buying it?

AI-assisted (“vibe”) coding can dramatically cut build time and cost, which shifts the build-vs-buy math toward building — especially for differentiated features. Model your AI model-stack costs and faster build velocity above, and the tool shows whether building still beats a vendor SaaS subscription over your chosen horizon.

How do I calculate total cost of ownership for build vs. buy?

Add up the full multi-year cost of each path. For buying: license, implementation, support, and annual price increases. For building: engineering and AI/model costs, time-to-live, ongoing maintenance, and support. This tool computes both over your chosen horizon (1–5 years) and recommends the cheaper, lower-risk option for your inputs.

When does building software cost less than buying SaaS?

Building tends to win when the app is highly differentiating, has a long lifespan, vendor SaaS pricing is high or rising fast, and your build velocity is strong (e.g. AI-assisted development). Buying tends to win for short-lived, commodity, or compliance-sensitive needs. Enter your numbers above to find the crossover point.