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Project Effort Estimate Calculator

Work out project effort estimate instantly with clear inputs, formula shown and shareable results.

About Project Effort Estimate Calculator

Parametric estimating multiplies a size measure by a historical productivity rate, then adds contingency for known unknowns. Dividing total effort by team capacity gives elapsed duration — but only up to a point, since adding people to a late project rarely shortens it proportionally.

Formulas

Base effort

Base hours = Size units x Hours per size unit

Total effort

Total = Base hours x (1 + Contingency %)

Elapsed weeks

Weeks = Total hours / (Team size x 40)

Worked example

With the default values below, Project Effort Estimate Calculator returns Total effort of 5,184. Change any input above and every figure here is recalculated in your browser.

Inputs used

Estimated size (function points or equivalent)
480
Hours per size unit
9
Contingency
20
Team size
6

Results

Total effort
5,184
Effort in person-days
648.0
Elapsed weeks with the given team
21.6
Contingency included
864

Step by step

  1. 1Values used
  2. 2Base effort
  3. 3Total effort
  4. 4Elapsed weeks
  5. 5Total effort= 5,184
  6. 6Effort in person-days= 648.0
  7. 7Elapsed weeks with the given team= 21.6
  8. 8Contingency included= 864

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Where does the productivity rate come from?

Your own completed projects. Industry averages vary by an order of magnitude across domains and are close to useless without calibration.

Can I halve duration by doubling the team?

Almost never. Communication overhead grows with team size, and some work is inherently sequential.

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Project Effort Estimate Calculator – Calculate Total effort