"How much will this cost?" is the question every custom software conversation starts with, and most answers are either vague or misleading.

What actually drives the price

Scope is the biggest lever by far, a single-feature internal tool costs a fraction of a multi-platform customer-facing product with its own onboarding flow. Integrations with existing systems, your ERP, a payment gateway, a legacy database nobody fully documented, add real time regardless of how simple the core feature looks on paper, because integration work is where most of the unknown unknowns live. The number of platforms, web only versus web plus iOS plus Android, roughly multiplies effort rather than adding a flat amount. And ongoing maintenance, which most upfront quotes conveniently leave out, is a real recurring cost long after launch that needs to be part of any honest budget conversation from the start.

Rough ranges by project size

A small internal tool or minimum viable product typically runs in the low five figures. A mid-sized product with a handful of integrations and a real, growing user base sits in the mid five figures to low six figures. A multi-platform product with complex integrations, compliance requirements, or heavy custom business logic moves into six figures and beyond, and the gap between these tiers is almost always about integration complexity, not visual polish.

Why "it depends" is a legitimate answer

Two projects that sound nearly identical in a sales call can differ by three times in actual cost once the real integration requirements and edge cases surface during a proper discovery phase. An honest quote comes after scoping, never before it, no matter how much pressure there is to give a number on the first call, and an agency willing to commit to a fixed price before discovery is either padding the number heavily or planning to add change orders later.

Getting an accurate estimate

Insist on a discovery phase before accepting a fixed price. Any number given before your actual integrations and edge cases are mapped out in detail is a guess dressed up as a quote, and that gap between guess and reality is exactly where budget overruns come from later, usually surfacing as a surprise mid-project rather than an honest conversation upfront.

Quick answers

Why do custom software quotes vary so much between agencies? Mostly because they're scoping different things under the same word. Some include a true discovery phase and post-launch support baked into the number, others quote only the happy path and add costs later as change orders once reality sets in.

Should we budget for maintenance separately from the initial build? Yes, as a general rule budget roughly 15-20% of the initial build cost per year for maintenance and small improvements, since software that isn't maintained at all tends to accumulate bugs and security issues that cost far more to fix later than to prevent along the way.