Project Estimate Calculator
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This free project estimate calculator turns three hour estimates into a project price. Enter optimistic, most likely and pessimistic hours, your hourly rate, a contingency buffer and other costs. It uses three-point (PERT) estimating to give expected hours, labor cost, contingency and a total. Built for freelancers, agencies and project managers quoting work. Free, no sign-up.
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Combines best case, most likely and worst case hours into one expected figure with the PERT formula.
Multiplies expected hours by your hourly rate, then adds contingency and other costs for a total project price.
Adds a percentage buffer for unknowns, shown as its own line so clients and teams can see it.
Each result shows the formula underneath. Copy the figures into a quote, proposal or spreadsheet.
Three steps from a blank form to a result you can use.
Fill in optimistic, most likely and pessimistic hours, then your hourly rate, contingency buffer and other costs. Example defaults show how it works.
The calculator shows expected hours, labor cost, contingency and total project price, with the formulas.
Copy the figures into a proposal, or adjust the estimates to see how risk changes the price.
A single hour estimate hides risk. Three-point estimating asks for a best case, a likely case and a worst case, then weights them into one expected figure you can price from.
PERT stands for Program Evaluation and Review Technique. Its three-point formula weights the most likely estimate four times as heavily as the two extremes:
Expected hours = (Optimistic + 4 × Most likely + Pessimistic) ÷ 6
The result usually lands a little above your most likely figure, because real projects tend to run over more often than they finish early. That pull toward the pessimistic side is the point. It builds known risk into the hours before you add any contingency.
| Method | Formula | When we would use it |
|---|---|---|
| PERT (weighted) | (O + 4M + P) ÷ 6 | Most client projects, where the likely case is a fair guess |
| Triangular (simple average) | (O + M + P) ÷ 3 | New kinds of work where you trust the likely case less |
You can also gauge uncertainty by hand with (Pessimistic minus Optimistic) ÷ 6, the usual PERT standard deviation. A wide gap between best and worst case tells you the scope needs more detail before you quote.
Example: This is an illustration, not a real quote. A studio estimates a brand refresh at 80 hours best case, 100 hours most likely and 150 hours worst case. It charges $90 an hour, adds a 10% contingency buffer and expects $600 of other costs for fonts and stock images.
The rough uncertainty is (150 minus 80) ÷ 6, about 12 hours. We would quote around $11,000 and write down what the price assumes, such as two rounds of revisions. Check the on-screen breakdown to see exactly which costs your contingency covers.
Contingency covers the unknowns that your three estimates cannot see: a stakeholder joins late, a file format breaks, a third party is slow. It is not padding for work you already know about. That work belongs in the hour estimates.
We suggest picking the buffer after you look at the gap between optimistic and pessimistic hours. A wide gap already signals risk. Adding a large buffer on top can double count it.
We treat the result as the start of a quote, not the end. Read the total, then ask whether the client would see it as fair for the value delivered. If not, revisit scope before you cut the price.
Quick answers about the Project Estimate Calculator.
A three-point estimate uses a best case, a most likely case and a worst case instead of one number. The PERT version weights the likely case four times: (optimistic + 4 × most likely + pessimistic) ÷ 6. With 80, 100 and 150 hours, the expected effort is 105 hours.
Break the work into tasks, estimate hours for each in three cases, and combine them into expected hours. Multiply by your hourly rate for labor cost, add a contingency buffer for unknowns, then add other costs such as software, stock assets or fees. That total is the basis of your quote.
It depends on how well you know the work. Familiar, clearly scoped projects need a smaller buffer, while new technology, vague briefs or many stakeholders need more. Look at the gap between your best and worst case first, since a wide gap already builds some risk into the expected hours.
Because worst case estimates usually sit further from the likely case than best case ones. If your best case is 20 hours under and your worst case 50 hours over, the PERT average moves toward the pessimistic side. That shift is intended and reflects how projects tend to overrun.
Yes, many freelancers and agencies do, but list your assumptions with the price, such as the number of revision rounds and what is out of scope. Then extra requests become priced changes rather than lost margin. The calculator does not add tax, so add any sales tax or VAT separately.
Yes. It is free, needs no sign-up and runs in your browser, so your estimates are not sent anywhere. There is no limit on how many times you calculate. Copy the results before you close the page, because the calculator does not save past estimates or keep a history for you.
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