Understanding how to estimate software development cost starts with accepting that software is not an off-the-shelf product. The price depends on scope, team composition, technical risk and the pricing model you choose. This guide explains how costs are built up, how fixed price and time and material (T&M) compare, and which budget items people most often forget.
The basic software cost formula
Whatever the pricing model, the underlying maths is the same:
Total cost = Estimated effort (person-days) × Team day rate + External costs + Risk buffer
- Effort: design, development, testing, project management and release.
- Day rate: varies with seniority and role mix.
- External costs: hosting, third-party services, licences, app store accounts.
- Risk buffer: added when uncertainty is high.
Real numbers vary widely by team, location and currency, so treat online average price lists with caution.
What drives software development cost?
- Scope: every screen, business rule and user role adds effort.
- Platforms: web only, or iOS and Android too; native or cross-platform.
- Integrations: payments, ERP, accounting, maps and messaging are often the riskiest part of an estimate.
- Design: a component library versus a fully custom visual language.
- Security and compliance: personal, financial or health data require extra care.
- Scale: systems serving many concurrent users need a different architecture.
- Deadline pressure: adding people does not shorten timelines linearly.
Fixed price vs time and material
The key difference between the two models is who carries the risk.
Fixed price
Scope is defined in detail up front and a total price is agreed. The budget is predictable, but vendors include a risk buffer and every change becomes a separately priced change request.
Time and material
You pay for the time the team actually spends, usually monthly. Scope can evolve and priorities can shift. Flexibility is high, but you need regular reporting and disciplined prioritisation to manage the total.
| Criterion | Fixed price | Time and material |
|---|---|---|
| Budget predictability | High | Medium, managed with caps |
| Scope flexibility | Low, changes cost extra | High |
| Who carries risk | Mostly the vendor | Shared, mostly the client |
| Preparation needed | Detailed analysis first | Can start quickly |
| Best for | Well-defined small and mid-size projects | Evolving products, post-MVP growth |
Many teams combine the two: a fixed-price discovery phase followed by T&M or small fixed-price milestones. For ongoing work, a monthly dedicated software team can offer a predictable middle ground.
How estimates are made: discovery and work breakdown
Reliable estimates usually rest on a work breakdown structure. The project is split into modules, modules into screens and functions, and functions into small tasks, each estimated for design, development and testing. The smaller the pieces, the more realistic the numbers. Where uncertainty is high, such as integrating with a system whose documentation you have not seen, a range based on optimistic, expected and pessimistic scenarios is more honest than a single figure, and it explains the risk buffer in the proposal. When much of the scope is still unclear, a short paid discovery phase that maps user flows, sketches key screens and investigates technical risks is the best starting point. Its outputs belong to you, so you can use them to collect other quotes if you wish.
Commonly forgotten costs
- Maintenance: OS and library updates, security patches
- Infrastructure: servers, databases, storage, CDN
- Third-party services: maps, SMS, email, payments, AI API usage
- App store accounts: Apple Developer Program and Google Play developer fees
- Content and data migration
- Your own team's time for meetings, testing and acceptance
Some of these look small, but their yearly totals add up. For usage-based services such as AI or maps, model how costs will grow with your user base before launch.
How to get a more accurate quote
- Write down the business goal and core user flows.
- Split features into must-have and later.
- List required integrations and existing systems.
- Share your budget range so the vendor can shape scope around it.
- Ask for assumptions and exclusions to be stated explicitly.
For uncertain projects, a paid discovery phase leads to far more realistic estimates. See how we scope work on our web development and mobile app development pages.
At BernSoftware we share scope, assumptions and risks line by line in every proposal. Contact us for a transparent estimate for your project.
Frequently asked questions
How much does a simple mobile app cost?
A single number would be misleading. An app with a few screens and no integrations can cost a fraction of one with payments, user roles and an admin panel. The most reliable approach is to request itemised quotes from several vendors based on your core feature list.
What happens if scope changes in a fixed-price project?
A change request process usually applies. The vendor estimates the time and cost impact, and once you approve, it is added to the plan. This process should be defined in the contract from the start.
How do I control budget in a time and material project?
Set a monthly or per-sprint cap, ask for regular time reports and review priorities at the start of each sprint. That keeps spending visible without giving up flexibility.
Planning a project like this?
Plan it in 10 steps