Effort estimation is one of the most uncomfortable tasks in a project.
Say a number that is too high, and stakeholders feel it’s overestimated.
Say a number that is too low, and you struggle later.
The truth is, no estimate is perfect, but it can be structured, transparent and defendable. That is enough to gain trust and keep control.
Here is a simple framework you can start using in your projects.
Step 1: Think in Phases, Not Just in Total Effort
Instead of asking “How many person-days for this project?”, break it into phases:
- Requirements
- Design
- Development (including unit testing)
- System Testing
- UAT Support
- Hypercare / Warranty
This does two things:
- It forces you to think about the whole lifecycle
- It reveals where effort is likely to get ignored (often testing and UAT)
Even if you don’t know exact numbers yet, you can start with relative weightage.
Step 2: Start from Development + UT (Dev+UT)
In many software projects, Dev+UT is the most visible effort component.
You often have a better feel for:
“For this feature, roughly how many days of development effort will it take?”
So start with:
- Dev+UT Effort (Y) – for example, 100 person-days
- Dev+UT % of total – for example, 40%
From this, you can back-calculate an approximate total project effort.
If Dev+UT is 40%:
Total Effort = Y / 0.40
Total Effort = 100 / 0.40 = 250 person-days
Now the conversation is not “100 days of development only”, it’s “250 days for the whole project”.
Step 3: Spread the Remaining 60% Across Other Phases
If Dev+UT is 40%, the remaining 60% belongs to:
- Requirements
- Design
- System Testing
- UAT
- Hypercare
You can define a base pattern, for example:
- Requirements – 20%
- Design – 15%
- Testing – 15%
- UAT – 5%
- Hypercare – 5%
These numbers are not fixed rules. They are starting points that you adjust based on:
- Complexity
- Team maturity
- Customer involvement
- Integration level
A good tool or spreadsheet can auto-balance these percentages so they always add up correctly when you tweak them.
Step 4: Convert Hours to Person-Days Correctly
Another common confusion: hours vs person-days.
You can keep it simple:
- 1 person-day = 8 hours
- Or, for offshore teams, 1 PD = 8.5 or 9 hours
Use a toggle or a fixed conversion; the important part is being consistent.
Once you have total hours per phase:
Person-Days = Hours / HoursPerDay
This helps you speak in PDs for planning, but still stay grounded in real hours.
Step 5: Use an Effort Estimator Instead of Guessing Every Time
You don’t have to do this math manually every time.
An Effort Estimator can:
- Take Dev+UT effort (Y)
- Take Dev+UT %
- Take phase-wise %
- Auto-calculate total effort
- Show phase-wise PDs
- Allow toggling between hours and PDs
- Keep changes transparent
This turns estimation into a structured conversation instead of a defensive fight.
Step 6: Common Estimation Mistakes to Avoid
Some patterns show up again and again:
- Ignoring non-dev work – no effort for clarifications, environment issues, or coordination
- Underestimating testing – especially integration and regression
- No effort for UAT and hypercare – assuming customer will handle everything
- Not revisiting estimates after major changes in scope or approach
Your framework should make these visible.
When people see the full phase breakdown, they understand where the effort goes.
Step 7: Use Estimation as a Communication Tool
A good estimate is not just a number; it is a story of how the project will unfold:
- How much time is spent understanding the problem
- How much coding effort is really needed
- How much care you’re investing in quality and stabilization
When you walk stakeholders through the phase-wise breakdown, they see:
- Thoughtfulness
- Transparency
- Professionalism
And that builds trust.