Eltherion

FREE TOOL

Custom Software Development Cost Calculator

Build cost, yearly maintenance, and 3–5 year total cost of ownership — the number most estimates leave out. Transparent assumptions. No email gate.

Your project

Complexity

Estimate

Build (one-time)

$166k$630k

Maintenance / evolution (per year)
$30k – $113k
Infrastructure & ops (per year)
~$23k
Year-1 total
$219k – $766k
3-year TCO
$324k – $1.04M
5-year TCO
$429k – $1.31M

Want a real number instead of a range? Tell us what you're building — a senior engineer will scope it with you.

Get a real estimate

How this calculator works

Most cost content quotes a build number and stops. The build is only the entry price: real total cost of ownership includes maintenance and evolution (15–20% of the build per year), infrastructure and operations, and — for AI systems — model inference. This calculator starts from base ranges by product type with a senior US team, multiplies by scope, adds the complexity items that actually move budgets (integrations, enterprise auth, multi-tenancy, compliance, AI features), applies a team-composition factor, and projects the 1-, 3-, and 5-year totals.

Every assumption is visible in the tool. If a vendor's quote is far below the low end of your range, the difference is usually missing scope — ask what happens to maintenance, integrations, and admin tooling before you sign. For the make-or-buy version of this decision, use the build vs. buy calculator.

Common questions

How much does custom software development cost in 2026?
With a senior US team, an internal tool runs $60k–$150k, a customer-facing web app $120k–$300k, a mobile app $120k–$450k, a B2B SaaS platform $150k–$600k, and a production AI system $60k–$300k for a first release. Scope, integrations, compliance, and team seniority move those ranges — that's exactly what this calculator models.
Why do software cost estimates vary so much between vendors?
Because cheap quotes usually exclude scope: maintenance, infrastructure, integrations, admin tooling, and the rework that junior teams generate. Comparing quotes without comparing what's included is how projects end up costing double. Always compare 3-year TCO, not the build quote.
What does software maintenance cost per year?
Plan on 15–20% of the original build cost per year for maintenance and evolution — dependency updates, platform changes, bug fixes, and the small features that keep the product competitive. Software that gets zero maintenance budget degrades into legacy within two to three years.
Is this calculator a quote?
No — it's a planning range built from real engagement economics so your budget conversation starts honest. A real quote requires scoping: what you're building, what exists today, and what done means. That conversation with a senior engineer is free.

Related: custom software development · SaaS development · mobile app development