WinnieProject Estimate Calculator
Estimate a project task by task in best, likely and worst case, add the work nobody lists and get the hours and a price you can quote.
Tasks in hours
3
9
10
13
3.5
4
Estimate per task = (best + 4 × likely + worst) ÷ 6. Break the work into tasks of a day or less.
Corrections and price
Calls, email, feedback rounds. 15 to 25% for most projects.
Actual ÷ estimated hours on past projects. 1.2 if you do not know yet.
For the number of working days.
Your estimate
61.2hours
Quote
€4,600
Working days
10.5 at 6 h
- Sum of likely (gut feeling)
- 39 h
- Task estimates (PERT)
- 42.5 h
- Hidden work (+20%)
- +8.5 h
- Personal factor (× 1.2)
- +10.2 h
- Estimate
- 61.2 h
- × €75 per hour, rounded up
- €4,600
How the calculator works
The calculator combines three corrections that make freelance estimates reliable:
-
A three-point estimate per task. For every task you enter a best case, a most likely case and a worst case. The PERT formula weighs them into one number:
Estimate = (best + 4 × likely + worst) ÷ 6
-
Hidden work on top. Calls, email, feedback rounds, project management and handover never show up in a task list, but they always show up in your hours.
-
Your personal factor. Everyone estimates with a personal bias. If your past projects took 20% longer than planned, you multiply by 1.2.
The result is the number of hours you should plan and quote, plus the price at your hourly rate and the number of working days it fills.
Step by step
Break the work down. List the tasks, each small enough to finish in a day or less. Big tasks hide the most risk, because nobody can estimate "Build the website" in one number.
Estimate in ranges. For each task ask three questions: how long if everything goes smoothly, how long most likely, and how long if the client changes their mind twice and the CMS fights back. The worst case does not have to be likely; it has to be possible.
Add the hidden work. For most freelance projects 15 to 25% is right. Choose the top of the range when there are many stakeholders, many feedback rounds or a client you have not worked with before.
Apply your factor. If you do not know it yet, start with 1.2. Then compare your estimates with your tracked hours after every project and adjust it.
A worked example
The calculator opens with a five-page website for a café. Adding up the "likely" column gives 39 hours, which is what most people would quote. The three-point estimates add up to 42.5 hours, 20% hidden work brings it to 51 hours, and a personal factor of 1.2 to 61.2 hours.
At €75 per hour that is a quote of €4,600 instead of €2,925. Quoting the gut feeling would have meant working about 22 hours for free.
From estimate to quote
If you bill by the hour, the estimate is what you tell the client to expect, and it protects you from the awkward conversation when the invoice is higher than they thought.
If you quote a fixed price, the ranges and your personal factor already cover most of the risk, so keep any extra contingency small. What matters more is a clear list of what is included and how many feedback rounds there are. Anything outside it becomes a change request instead of scope creep.
Do not know what hourly rate to use? The freelance rate calculator works it out from your income goal and costs.
Common estimating mistakes
- Estimating only the likely case. Things rarely go better than likely, and often worse. The average ends up above the likely case.
- Forgetting the client's part. Waiting for feedback, content and approvals stretches the timeline even if it does not add hours.
- Copying the last project. Similar projects are a good starting point, but check what is different this time.
- Never checking afterwards. Without comparing estimate and actual hours, the next estimate will be just as wrong.
For the full method, read how to estimate project time as a freelancer.
Get better with every project
Your personal factor is the most valuable number in this calculator, and you can only learn it from tracked time. Winnie tracks your hours per client with one click, so after a few projects you know exactly how far off your estimates are and can correct for it.
Frequently asked questions
- What is a three-point or PERT estimate?
- You estimate every task three times: best case, most likely and worst case. The PERT formula (best + 4 × likely + worst) ÷ 6 weighs the likely case most but lets the risk in the worst case pull the number up, which corrects the optimism of single-number estimates.
- How much should I add for meetings, email and revisions?
- For most freelance projects 15 to 25 percent on top of the task estimates. Projects with many stakeholders, many feedback rounds or many meetings belong at the top of that range.
- What is a personal estimation factor?
- Your actual hours divided by your estimated hours on past projects. If your last projects took 30 percent longer than planned, your factor is 1.3 and you multiply new estimates by it until your estimates improve. You need tracked time to know it.
- How do I turn an estimate into a fixed price quote?
- Multiply the estimated hours by your hourly rate and round up. The ranges and your personal factor already cover most of the risk, so keep extra contingency small and write down clearly what is included, so new wishes become change requests.
Embed this calculator
Add the project estimate calculator to your website, blog or course for free. Paste the code where it should appear. It adapts to the width of your page and sets its own height.
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