Custom Software Development Cost: A Realistic Budget
Short answer
Custom software development cost equals estimated hours multiplied by the hourly rate, plus maintenance over the system's life. A 300-hour internal tool at $100 an hour costs about $30,000; an integrated business application can pass $200,000. Robert Glass puts maintenance at 40 to 80 percent of lifetime software cost, so budget for years of upkeep, not just the build.
Ask three vendors to quote the same piece of software and the highest number is often three times the lowest. Usually nobody is trying to rip you off. Each vendor priced a different project, because the brief left room for interpretation.
The core formula is simple: estimated hours times hourly rate, plus the cost of running and changing the system for as long as you use it. Both parts are tricky. Hours are uncertain at the start, and the running cost is the line most budgets forget.
What does an hour of development cost?
Rates vary enormously by country and by type of supplier, so start with a baseline you can check. The US Bureau of Labor Statistics reports a median annual wage of $135,980 for software developers in May 2025. Spread over 2,080 paid hours, that’s roughly $65 an hour in salary alone, before benefits, payroll taxes, equipment, management time and the hours nobody can bill.
Freelancers and agencies charge well above that base salary, because they carry those costs plus utilisation risk. For a European reference point, freelancermap analysed 2,337 freelance developer profiles in Germany, Austria and Switzerland in September 2026 and found a median asking rate of €90 an hour in Germany and Austria and €129 in Switzerland.
Source: US BLS Occupational Outlook (May 2025 median wage, converted at 2,080 h); freelancermap DACH profile analysis, September 2026
Agencies and studios typically quote more than individual freelancers, because project management, QA, holiday cover and delivery risk are baked into the rate. You get a team rather than one person. Whether that’s worth it depends on how much coordination you can handle yourself.
Three worked examples
The table below uses $100 an hour purely as an illustrative rate. The hour figures are assumptions for the arithmetic, not market benchmarks. Swap in the numbers from your own quotes.
| Project | Assumed effort | Cost at $100/h |
|---|---|---|
| Internal tool: form, approval step, export, single sign-on | 300 h | $30,000 |
| Customer portal: roles, documents, payments, email | 900 h | $90,000 |
| Business application: ERP integration, data migration, mobile app | 2,200 h | $220,000 |
What drives the hours? Rarely the screens you can see. The expensive parts are integrations with legacy systems, data migration, role and permission models, supporting several platforms, and anything touching security or privacy. Adding native iOS and Android apps on top of a web app can nearly double the front-end effort, depending on the technology.
For a sharper number you need an estimate based on concrete requirements. Our guide to software estimation techniques shows how to build one.
The forgotten line: maintenance and evolution
This is where most budgets go wrong. Robert Glass, in Facts and Fallacies of Software Engineering, reports that maintenance consumes 40 to 80 percent of total software cost, 60 percent on average. Roughly 60 percent of that maintenance is enhancement, not bug fixing. Software that people use keeps growing.
Take the average and the initial build is only about 40 percent of what the software will cost over its life.
- Initial build (900 h × $100)
- $90,000
- Share of lifecycle cost
- 40%
- Maintenance and evolution (60%)
- $135,000
- Total lifecycle cost
- $225,000
Projection using Glass's average (maintenance = 60% of lifecycle cost). A rough guide, not a forecast.
That number shocks people. It’s still more honest than a budget that ends at launch. Running costs include hosting and security patches for libraries and frameworks. Then there are updates for new browser and OS versions, monitoring, backups and user support.
Costs your vendor will never quote
One line is missing from every vendor’s estimate: your own people’s time. Someone must answer questions, review progress, provide test data and sign off at the end. Agile delivery makes that a defined role, the product owner, and it isn’t a side job for Friday afternoons.
Here is a useful sanity check: who will answer product questions within 24 hours, and how many hours a week do they have for it? If the answer is “nobody” or “two hours”, the project gets more expensive, because developers either wait or build on guesses that later need reworking.
Third-party services add up too. Maps, transactional email, payment processing and SMS are cheap individually and billed by usage. Five years later they add up to a real number.
How much contingency, and where?
A budget without contingency is a bet. Steve McConnell’s cone of uncertainty shows estimates at the concept stage can be off by a factor of four, and even with complete requirements actual effort may land a third lower or 50 percent higher.
For a well-specified project, 15 to 25 percent contingency is a reasonable starting point. Keep it as a visible line rather than spreading it across items, or it gets quietly consumed and nobody notices the squeeze until too late.
Cutting scope is the alternative to a fat buffer. Limit must-haves to 60 percent of the budget, as recommended in MoSCoW prioritization, and your contingency comes in the form of features you can defer.
Making quotes comparable
Three steps turn three incomparable numbers into a real decision:
- Send a requirements document based on a clear template that names integrations, data migration and non-functional targets explicitly.
- Ask every vendor to break their quote into the same work packages, including project management and testing as well as deployment.
- Ask for their assumptions: what did they assume where your document was silent?
The third question tells you most. Vendors who state their assumptions have thought about your project. Vendors who give only a total may not have.
Contract structure matters as much as the number. Whether a capped time-and-materials deal or a fixed price suits you is covered in fixed price vs time and materials.
If you’d like to sanity-check a budget before going to tender, a studio such as OnlineBuilders, which builds custom software, offers a free initial technical consultation.
Next step: write down three figures for your project. The build budget, an annual budget for running and evolving the system, and the five-year total. If only the first one exists, your budget isn’t finished.
Questions people ask
Is a fixed price cheaper than time and materials?
Rarely. On a fixed price the vendor carries the risk and prices in a premium for it. It only comes out cheaper when scope is genuinely stable and the vendor underestimated, which is not a healthy outcome for either side.
How much should I budget for software maintenance each year?
Robert Glass found maintenance accounts for 40 to 80 percent of total lifecycle cost, 60 percent on average, and most of it is enhancements rather than bug fixes. Plan a recurring annual budget for security updates, platform changes and new features from day one.
Why do quotes for the same project vary so much?
Without a precise requirements document, each vendor prices a slightly different project. Different assumptions about integrations, data migration and testing easily explain a factor of two or three between quotes.
Is offshore development cheaper overall?
Hourly rates can be much lower, but coordination, time-zone gaps and rework add hidden cost. Compare total cost for a defined scope, including your own team's management time, rather than comparing rates alone.
