About Project Time Calculator
Free calculators for the math behind a project schedule, with formulas and worked examples you can check.
Project Time Calculator is a small set of free calculators for people who need the math behind a project schedule: how long the work takes, when it finishes, how uncertain the estimate is and which tasks decide the end date.
What it is, and what it is not
It is a calculator site. You enter numbers, and the answer appears with the formula and a worked example so you can check it. It is not a time tracker, a timesheet tool or project management software. There are no accounts, no stored projects and no reminders.
Who it is for
- Project managers and team leads who need a defensible duration or team size.
- PMP and CAPM students who want to check PERT and critical path exercises.
- Freelancers and small agencies who quote by the hour and need a finish date and cost.
- DIY and construction planners who want to know how long a job takes.
The calculators
- Project time calculator: effort to duration, finish date, cost and team size.
- PERT calculator: expected time, variance and on-time probability.
- Critical path calculator: earliest and latest times, float and the critical path.
- Hours to working days calculator: hours, days and weeks.
Who builds it
Project Time Calculator is built and maintained by Umesh Manral, a Business Analyst, Excel VBA automation expert and web application developer, who created it to track his own daily project tasks and save time.
How we keep it correct
Every formula has an automated test, and each worked example on the site uses numbers that the tests check against the calculator's code. The methodology page lists each formula, its source and its assumptions. If you find a result that looks wrong, tell us and include the inputs.
Last updated 19 October 2026. Reviewed by Umesh Manral. Business Analyst, Excel VBA automation expert and web application developer who built this site to track daily project tasks.