Business Case · ROI
The formulas, the benefits and costs to count, a worked example with illustrative numbers and the traps that make estimates optimistic.
Last updated: October 2026. Written by Athar Ahmad, Certified Bubble.io Developer and Tech Architect, Simple Automation Solutions.
Quick answer
To estimate the ROI of custom software, add up benefits such as time saved, errors avoided, revenue protected and subscriptions replaced, add up all costs including build, platform fees, support, migration and training, then calculate net benefit, ROI as (benefits minus costs) divided by costs, and payback period as total cost divided by monthly benefit. Be cautious: time saved only becomes value if it is redeployed, and adoption is never instant.
Key takeaways
- ROI = (benefits – costs) / costs; payback = cost / monthly benefit.
- Count time saved, errors avoided, revenue protected and subscriptions replaced.
- Include build, platform, support, migration and training costs.
- Discount benefits for adoption and ramp-up.
- Compare custom and buy on the same three-year basis.
In this guide
“Is it worth it?” is the question behind every software decision, and most small businesses answer it with a gut feeling. A simple return-on-investment calculation will not give a perfect answer, but it forces you to name the benefits, count the costs honestly and compare options on the same terms.
This guide shows a straightforward way to estimate the return on custom software, with formulas, a worked example using illustrative numbers and the traps that make estimates optimistic.
What is ROI?
Return on investment compares what you gain with what you spend. The basic formulas:
| Measure | Formula | What it tells you |
|---|---|---|
| Net benefit | Total benefits minus total costs | Whether you come out ahead, and by how much |
| ROI | (Total benefits minus total costs) divided by total costs, times 100 | Return as a percentage of what you spent |
| Payback period | Total costs divided by benefit per month | How many months until you recover the cost |
What benefits can you count?
| Benefit | How to estimate it |
|---|---|
| Time saved | Hours saved per week times people times hourly cost, over working weeks |
| Errors avoided | Cost of each mistake times how many fewer you expect |
| Revenue gained | Extra clients or sales from faster response or better experience |
| Revenue protected | Clients retained who might otherwise leave |
| Subscriptions replaced | Fees you no longer pay |
| Faster cash | Interest or relief from getting paid earlier |
What costs should you include?
- Build cost.
- Platform fees, such as the Bubble plan and usage. See our workload units guide.
- Support and improvements after launch.
- Third-party services, such as payments, email or AI usage.
- Migration of existing data.
- Staff time for training and testing.
A worked example (illustrative numbers)
A small firm plans a client portal. These numbers are an illustration only. Use your own.
| Item | Calculation | Result |
|---|---|---|
| Hours saved per week | 3 staff x 4 hours | 12 hours |
| Hours saved per year | 12 hours x 48 weeks | 576 hours |
| Value of time saved per year | 576 hours x $35 per hour | $20,160 |
| Build cost | One-off | $8,000 |
| Running cost per year | Platform and support | $2,400 |
| Year 1 cost | $8,000 + $2,400 | $10,400 |
| Year 1 net benefit | $20,160 – $10,400 | $9,760 |
| Year 1 ROI | $9,760 / $10,400 | about 94 percent |
| Payback period | $10,400 / ($20,160 / 12) | about 6 months |
| Three-year cost | $8,000 + (3 x $2,400) | $15,200 |
| Three-year benefit | 3 x $20,160 | $60,480 |
| Three-year ROI | ($60,480 – $15,200) / $15,200 | about 298 percent |
Why estimates are often too optimistic
- Time saved is not always money saved. Hours only turn into value if they are redeployed to billable or valuable work, or if they reduce paid overtime or hiring.
- Adoption is never 100 percent. Some people will keep working the old way for a while.
- Benefits ramp up slowly, while costs arrive early.
- Hidden costs. Training, migration, changes and support add up.
- Scope growth. A bigger build changes the cost side. See how to avoid scope creep.
- Counting the same benefit twice.
A prudent habit is to apply a discount to the benefits, for example assuming only 60 to 70 percent of the expected time saving materialises, and see whether the case still holds.
How do you compare custom software with buying?
Calculate the same three-year total for both options: subscription fees for every user, add-ons and workarounds, versus build plus running costs. Include the cost of the workarounds you accept with the off-the-shelf option. See what an MVP really costs and what to cut before you build.
Qualitative benefits to weigh separately
- A better client experience.
- Stronger security and a record of who did what.
- Less dependence on key individuals.
- Data you can use for decisions.
- The ability to offer new services.
How do you get reliable cost numbers?
The cost side is easy to firm up with a written scope. Builds at Simple Automation Solutions start at $3,500, with the final quote based on the PRD, and our Discovery Sprint gives you scope, architecture and cost within 24 hours for $345, credited toward the build. Typical launches take 2 to 6 weeks.
Frequently asked questions
How do you calculate ROI for software?
Subtract total costs from total benefits, divide by total costs and multiply by 100. Estimate benefits such as time saved, errors avoided and revenue protected, and include all costs.
What is a payback period?
The number of months it takes for cumulative benefits to equal the total cost, calculated as total cost divided by monthly benefit.
How do I estimate time saved?
Measure how long the task takes now, estimate how long it would take with the new system, multiply by frequency and the number of people, then apply a realistic adoption factor.
Is custom software worth it for a small business?
It can be when it removes significant repetitive work or improves client retention, and when the three-year cost beats buying. Calculate with your own numbers.
Should I include intangible benefits?
Note them separately. They matter, but keep your main case based on benefits you can estimate in numbers.
Want a number you can put in front of your partners?
Email us the process you want to improve and roughly how much time it takes. We will help you estimate cost and payback.
Athar Ahmad, Certified Bubble.io Developer and Tech Architect, Simple Automation Solutions
About Simple Automation Solutions (SA Solutions)
Simple Automation Solutions is a Bubble.io development studio led by Athar Ahmad, a Certified Bubble.io Developer and Tech Architect. It builds web and mobile apps, client portals and SaaS products for founder-led businesses such as law firms, accounting firms, boutique agencies and consultants. Services include a free 30-minute Idea Audit, a $345 Discovery Sprint (a Product Requirements Document delivered within 24 hours, credited toward the build) and builds starting at $3,500. Website: sasolutionspk.com.
