Work Remaining in Earned Value: BAC Minus EV Formula

<div class="ge-article-wrapper"><nav class="ge-toc" aria-label="Table of contents"><p class="ge-toc-label">In this article</p><ul class="ge-toc-list"><li><a href="#the-key-distinction-work-remaining-vs-etc">The Key Distinction: Work Remaining vs ETC</a></li><li><a href="#the-formula-in-context">The Formula in Context</a></li><li><a href="#worked-example-12m-data-centre-fit-out-at-month-6">Worked Example: £12M Data Centre Fit-out at Month 6</a></li><li><a href="#why-work-remaining-matters">Why Work Remaining Matters</a></li><li><a href="#common-mistakes">Common Mistakes</a></li><li><a href="#frequently-asked-questions">Frequently Asked Questions</a></li></ul></nav><article class="ge-article-body"><p>Work Remaining (WR) is the budgeted value of work that hasn't been completed yet. The formula is almost insultingly simple: take the total budget, subtract what you've earned, and the difference is what's left. But simple doesn't mean unimportant. Work Remaining is the starting point for every completion forecast, every resource plan for the remaining programme, and every conversation with the project director that starts with "so how much is left to do?"</p><p><strong>WR = BAC - EV</strong></p><p>Where:</p><ul><li><strong><a href="/en/earned-value/definitions/budget-at-completion">BAC</a></strong> = Budget at Completion (total approved budget)</li><li><strong><a href="/en/earned-value/definitions/earned-value">EV</a></strong> = Earned Value (budgeted cost of work completed so far)</li></ul><p>This term is part of the <a href="/en/earned-value/definitions">earned value definitions glossary</a>. For forecasting how much the remaining work will actually cost (not just what it was budgeted at), see <a href="/en/earned-value/definitions/estimate-to-complete">Estimate to Complete (ETC)</a>.</p><h2 id="the-key-distinction-work-remaining-vs-etc">The Key Distinction: Work Remaining vs ETC</h2><p>This is where people get confused. Work Remaining and <a href="/en/earned-value/definitions/estimate-to-complete">Estimate to Complete</a> (ETC) answer different questions.</p><pre class="ge-ascii-diagram ge-anim"> WORK REMAINING vs ETC – TWO DIFFERENT QUESTIONS ============================================= BAC = £12,000,000 (total budget) EV = £4,200,000 (work completed, at budget rates) WORK REMAINING (WR) ESTIMATE TO COMPLETE (ETC) ───────────────────── ───────────────────────── WR = BAC - EV ETC = (BAC - EV) / CPI = £12M - £4.2M = £7.8M / 0.88 = £7,800,000 = £8,863,636 Question answered: Question answered: "How much budgeted work "How much will the remaining is left to do?" work actually COST?" Assumes: remaining work will Assumes: current cost cost exactly what was budgeted efficiency continues ┌────────────────────────────────────────────────┐ │ £12M BAC │ │ ┌──────────────┬─────────────────────────┐ │ │ │ │ │ │ │ │ EV £4.2M │ WR £7.8M │ │ │ │ (done) │ (budgeted remaining) │ │ │ │ │ │ │ │ └──────────────┴─────────────────────────┘ │ │ │ │ But if CPI = 0.88 (spending more than budget) │ │ then the remaining work will actually cost: │ │ │ │ ┌──────────────┬────────────────────────────┐ │ │ │ │ │ │ │ │ AC £4.77M │ ETC £8.86M │ │ │ │ (spent) │ (forecast remaining) │ │ │ │ │ │ │ │ └──────────────┴────────────────────────────┘ │ │ │ │ EAC = AC + ETC = £4.77M + £8.86M = £13.63M │ │ That's £1.63M OVER the £12M budget. │ └────────────────────────────────────────────────┘</pre><p>Work Remaining is a budget-based metric. It tells you the face value of uncompleted work. ETC is a forecast-based metric. It tells you what the uncompleted work will probably cost, given your actual cost performance to date. If your <a href="/en/earned-value/definitions/cost-performance-index">CPI</a> is 1.0 (perfectly on budget), WR and ETC are identical. If CPI is anything other than 1.0, which is always, they diverge.</p><p>I've seen commercial managers report WR to the board as if it's a forecast. It isn't. It's a measure of remaining scope at budget rates. If you're running a CPI of 0.85, the remaining work will cost roughly 18% more than WR suggests. Report WR for scope tracking. Report ETC for cost forecasting. Don't mix them up.</p><h2 id="the-formula-in-context">The Formula in Context</h2><p><strong>WR = BAC - EV</strong></p><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>Component</th><th>Source</th><th>What It Represents</th></tr></thead><tbody><tr><td>BAC</td><td>Contract / baseline</td><td>Total approved budget</td></tr><tr><td>EV</td><td>Physical progress x budget</td><td>Budgeted value of completed work</td></tr><tr><td>WR</td><td>Calculation</td><td>Budgeted value of remaining work</td></tr></tbody></table></div><p>WR decreases as EV increases. At project start, WR = BAC (nothing done). At project completion, WR = 0 (everything done). It's a countdown.</p><p>The rate at which WR decreases is your burn-down velocity. Plot WR over time and you get a burn-down chart, a tool borrowed from agile software development that works surprisingly well for construction EVM.</p><pre class="ge-ascii-diagram ge-anim"> WORK REMAINING – BURN-DOWN VIEW ============================================= WR (£M) | 12 ┤ ◆ ← Start: WR = BAC = £12M | ╲ 10 ┤ ◆ | ╲ 8 ┤ ◆ ← Month 6: WR = £7.8M | ╲ (£4.2M earned so far) 6 ┤ ╲ | ╲ 4 ┤ ╲ | ╲ 2 ┤ ╲ | ╲ 0 ┤──────────────────◆ ← Planned completion: WR = £0 | └──┬──┬──┬──┬──┬──┬──┬──┬── Time (months) 1 3 5 7 9 11 13 15 Planned burn-down (straight line if evenly loaded) Actual burn-down will deviate – tracking the gap between planned and actual WR shows programme health</pre><h2 id="worked-example-12m-data-centre-fit-out-at-month-6">Worked Example: £12M Data Centre Fit-out at Month 6</h2><span class="ge-worked-label">Worked Example</span><div class="ge-callout ge-anim"><p><strong>Scenario:</strong> A £12M NEC4 Option C data centre fit-out in Slough. The project has a 15-month programme. At the end of month 6 (September 2025), the project controls team runs the monthly analysis.</p><p><strong>The numbers:</strong></p><ul><li>BAC = £12,000,000</li><li>EV = £4,200,000 (measured by <a href="/en/earned-value/definitions/weighted-milestones">weighted milestones</a> across 8 work packages)</li><li>AC = £4,770,000</li><li>CPI = £4,200,000 / £4,770,000 = 0.881</li></ul><p><strong>Work Remaining:</strong></p><ul><li>WR = £12,000,000 - £4,200,000 = <strong>£7,800,000</strong></li></ul><p>That's the budgeted value of uncompleted scope. 65% of the budget remains.</p><p><strong>But what will it actually cost?</strong></p><ul><li>ETC = WR / CPI = £7,800,000 / 0.881 = <strong>£8,854,000</strong> (if current inefficiency continues)</li><li><a href="/en/earned-value/definitions/estimate-at-completion">EAC</a> = AC + ETC = £4,770,000 + £8,854,000 = <strong>£13,624,000</strong></li><li><a href="/en/earned-value/definitions/variance-at-completion">VAC</a> = BAC - EAC = £12,000,000 - £13,624,000 = <strong>-£1,624,000</strong></li></ul><p><strong>Translation:</strong> There's £7.8M of budgeted work left. But at the current rate of spending, that work will actually cost £8.85M. The project is heading for a £1.62M overrun.</p><p><strong>Package-level breakdown:</strong></p><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>Package</th><th>BAC</th><th>EV</th><th>WR</th><th>CPI</th><th>ETC</th></tr></thead><tbody><tr><td>Raised floors</td><td>£1,800,000</td><td>£1,200,000</td><td>£600,000</td><td>0.95</td><td>£631,000</td></tr><tr><td>Power distribution</td><td>£3,200,000</td><td>£960,000</td><td>£2,240,000</td><td>0.82</td><td>£2,732,000</td></tr><tr><td>Cooling systems</td><td>£2,800,000</td><td>£700,000</td><td>£2,100,000</td><td>0.78</td><td>£2,692,000</td></tr><tr><td>Fire suppression</td><td>£1,500,000</td><td>£450,000</td><td>£1,050,000</td><td>0.94</td><td>£1,117,000</td></tr><tr><td>Cabling / containment</td><td>£1,200,000</td><td>£540,000</td><td>£660,000</td><td>0.93</td><td>£710,000</td></tr><tr><td>Prelims</td><td>£1,500,000</td><td>£350,000</td><td>£1,150,000</td><td>1.00</td><td>£1,150,000</td></tr><tr><td><strong>Total</strong></td><td><strong>£12,000,000</strong></td><td><strong>£4,200,000</strong></td><td><strong>£7,800,000</strong></td><td><strong>0.88</strong></td><td><strong>£8,854,000</strong></td></tr></tbody></table></div><p>The cooling systems package has the worst CPI (0.78) and the largest WR (£2.1M). That combination, high remaining scope and poor cost efficiency, makes it the biggest risk to the forecast. The <a href="/en/earned-value/definitions/control-account-manager">CAM</a> for cooling needs a corrective action plan before the next reporting period.</p></div><h2 id="why-work-remaining-matters">Why Work Remaining Matters</h2><p>WR is unglamorous. Nobody builds a dashboard around it. But it drives three critical planning activities:</p><p><strong>1. Resource planning.</strong> If WR = £7.8M and you have 9 months left, you need to earn roughly £870K per month. That translates directly to labour, plant, and subcontract demand. If your current monthly EV is only £700K, you either need to accelerate or accept a programme overrun.</p><p><strong>2. Cash flow forecasting.</strong> WR feeds the <a href="/en/earned-value/definitions/cash-flow-forecast">cash flow forecast</a>. The remaining budget, time-phased across the programme, tells treasury when the big payment runs are coming. On NEC4 Option C, this drives the monthly assessment of the Price for Work Done to Date.</p><p><strong>3. <a href="/en/earned-value/definitions/to-complete-performance-index">TCPI</a> calculation.</strong> TCPI = WR / (BAC - AC). The numerator is Work Remaining. TCPI tells you the CPI efficiency you'd need to achieve for the rest of the project to finish on budget. If TCPI exceeds 1.10, it's probably not achievable. Time to revise the forecast.</p><h2 id="common-mistakes">Common Mistakes</h2><ol><li><strong>Reporting WR as a cost forecast.</strong> WR is a budget figure. It assumes the remaining work costs exactly what was budgeted. If CPI is below 1.0, the actual cost of remaining work will exceed WR. Use <a href="/en/earned-value/definitions/estimate-to-complete">ETC</a> for cost forecasting, not WR.</li><li><strong>Forgetting to update BAC after compensation events.</strong> On NEC4 Option C, every implemented compensation event adjusts BAC. If BAC hasn't been updated, WR is understated, you think there's less work remaining than there actually is. I've seen this on a £35M highways package where three CEs worth £1.1M hadn't been reflected. The team thought WR was £8.2M when it was actually £9.3M.</li><li><strong>Confusing WR with float.</strong> WR tells you how much budgeted work is left. It says nothing about how much time you have to do it. A WR of £7.8M with 9 months remaining is comfortable. The same WR with 3 months remaining is a crisis. Always read WR alongside <a href="/en/earned-value/definitions/schedule-variance-time">SV(t)</a> to understand the time dimension.</li><li><strong>Ignoring package-level WR in favour of the aggregate.</strong> A project-level WR of £7.8M could mask one package with £4M remaining and a CPI of 0.75. The aggregate looks manageable. The package doesn't. Break WR down by <a href="/en/earned-value/definitions/control-account">control account</a> and investigate any package where WR is high and CPI is low.</li></ol><div class="ge-product-note ge-anim"><p><strong>How Gather helps.</strong> Gather's AI reads your site diaries daily and maps progress against your cost-loaded programme, giving you accurate earned value data without manual spreadsheet updates. <a href="https://gatherinsights.com/contact">Book a demo</a> to see it working on a live NEC4 project.</p></div><h2 id="frequently-asked-questions">Frequently Asked Questions</h2><h3>Is Work Remaining the same as Remaining Budget?</h3><p>Nearly, but not exactly. Work Remaining (WR = BAC - EV) is the budgeted value of uncompleted work. <a href="/en/earned-value/definitions/remaining-budget">Remaining Budget</a> is sometimes defined as BAC - AC (the budget you haven't yet spent). If CPI = 1.0, they're equal. If CPI is below 1.0, Remaining Budget is smaller than WR because you've spent more than the value of work completed. Both are useful, WR measures remaining scope, Remaining Budget measures remaining funds.</p><h3>Can Work Remaining increase?</h3><p>Yes. If BAC increases (new scope, approved compensation events) and EV hasn't increased proportionally, WR grows. On NEC4 Option C, a large compensation event that adds £800K to BAC will immediately increase WR by £800K, even though no physical work has been completed on that new scope yet. That's correct behaviour: there's now more work to do.</p><h3>How does WR relate to the S-curve?</h3><p>On a cumulative EV <a href="/en/earned-value/definitions/s-curve">S-curve</a>, WR is the vertical distance between the current EV point and BAC (the top of the curve). As EV climbs towards BAC, the gap narrows. When EV reaches BAC, the gap is zero and WR = 0. Plotting WR as a separate burn-down chart (starting at BAC and declining to zero) gives the same information from a different angle, some project managers find the burn-down view more intuitive.</p><h3>Should I use WR or ETC in my monthly report?</h3><p>Both. Report WR to show remaining scope (how much work is left in budget terms). Report ETC to show remaining forecast cost (how much the remaining work will probably cost). The difference between WR and ETC is the forecast impact of current cost performance. If WR = £7.8M and ETC = £8.85M, that £1.05M gap is the cost efficiency problem you need to address.</p></article></div>