Project Budget Burn Calculator NZ
This project budget burn calculator tells you whether a time and materials job is on track while there is still time to do something about it. Hours logged against a budget only tell you how much money has gone. They do not tell you whether the work has kept pace, and a project can be half spent and a third done without anyone noticing until the last invoice. Earned value closes that gap by putting a dollar figure on the work actually finished, so you can set it against the dollars spent. You enter the project budget, the blended hourly rate the hours are charged at, the hours logged so far, your judgement of how much of the work is complete and the number of weeks the project has been running. The calculator gives you the amount spent, the earned value, the cost performance index, the estimate at completion and the forecast overrun, along with the hours left in the budget and how many weeks they will last at the current weekly burn. It is built for consultancies, agencies, engineers, developers and trades firms that bill clients for time against an agreed budget, and for project leads who need a number to take to the client before the budget is gone rather than after.
From the same team as Calculate.co.nz
Your Timesheets at jobtracker.co.nz logs your hours on a week grid or a timer that keeps counting when your phone locks, free on every plan. Career and Timesheets turns those hours into projects and rates, fixed fees and retainers, numbered invoices with GST only when you are registered, expenses and mileage, and the tax to set aside, from $4.99 a month billed yearly.
Log your hours free218.6 hours left in the budget, which lasts about 6.2 weeks at the current burn of 35.0 hours a week.
Work complete is your own judgement of how much of the job is finished, not the share of hours used. The forecast is only as good as that estimate, and it assumes the rest of the work runs at the same cost performance as the work so far.
How it works
The calculator uses the standard earned value measures. Spent to date is the hours logged multiplied by the blended rate: what the budget has used up. Earned value is the per cent complete multiplied by the budget: what the work finished so far was budgeted to cost. The cost performance index is earned value divided by spent. At 1, every dollar spent has bought a dollar of planned work; below 1, the work is costing more than planned, and above 1 it is costing less. The estimate at completion is the budget divided by the index, which is the final cost if the rest of the job performs the way the first part did. The forecast overrun is the estimate less the budget, and a negative overrun is shown as a forecast underspend.
The budget left is the budget less spent to date, and dividing it by the blended rate turns it into hours. The weekly burn is the hours logged divided by the weeks elapsed, and the hours left divided by that burn is the number of weeks before the budget is used up. Comparing those weeks with the work still to do is usually the quickest way to see whether the conversation with the client needs to happen now.
Worked example
A $60,000 budget is charged at a blended $140 an hour. After 6 weeks the team has logged 210 hours, so $29,400 has been spent, 49.0% of the budget. The project lead judges the work to be 40% complete, so the earned value is $24,000. The cost performance index is $24,000 divided by $29,400, which is 0.8163, shown as 0.82. Dividing the $60,000 budget by 0.8163 gives an estimate at completion of $73,500, the same as $60,000 multiplied by $29,400 and divided by $24,000. That is a forecast overrun of $13,500. The $30,600 left in the budget buys 218.6 more hours, and at 35.0 hours a week that lasts about 6.2 weeks.
| Measure | Working | Result |
|---|---|---|
| Spent to date | 210 hours at $140 | $29,400 |
| Earned value | 40% of $60,000 | $24,000 |
| Cost performance index | $24,000 divided by $29,400 | 0.82 |
| Estimate at completion | $60,000 divided by 0.8163 | $73,500 |
| Forecast overrun | $73,500 less $60,000 | $13,500 |
| Hours left in budget | $30,600 divided by $140 | 218.6 |
| Weekly burn | 210 hours over 6 weeks | 35.0 hours |
| Weeks until the budget runs out | 218.6 divided by 35.0 | 6.2 weeks |
Related calculators
- Blended Rate Calculator: the single hourly rate behind a team on different rates.
- Work in Progress Calculator: the value of time done but not yet billed.
- Fixed Fee vs Hourly Calculator: what an overrun does to your rate on a fixed price.
- Client Hours Allocation Calculator: how a week's hours split across clients and what they earn.