What Is Schedule Variance (SV) in EVM? Formula & Example

<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-formula">The Formula</a></li><li><a href="#how-sv-works-visually">How SV Works Visually</a></li><li><a href="#the-convergence-problem-svs-fatal-flaw">The Convergence Problem, SV's Fatal Flaw</a></li><li><a href="#worked-example-20m-flood-defence-at-month-8">Worked Example: £20M Flood Defence at Month 8</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>Schedule Variance (SV) tells you whether your project is ahead or behind programme, but it measures the gap in pounds, not in time. That catches people out. SV is the difference between <a href="/en/earned-value/definitions/earned-value">Earned Value</a> (what you've completed) and <a href="/en/earned-value/definitions/planned-value">Planned Value</a> (what you should have completed by now). Positive means ahead. Negative means behind. Zero means you're exactly on programme, which, in my experience, happens for about one reporting period on any given project before reality kicks in.</p><p><strong>SV = EV - PV</strong></p><p>This term is part of the <a href="/en/earned-value/definitions">earned value definitions glossary</a>. For the full variance breakdown including <a href="/en/earned-value/definitions/cost-variance">Cost Variance</a>, see the <a href="/en/earned-value/cost-schedule-variance">cost and schedule variance page</a>.</p><h2 id="the-formula">The Formula</h2><div class="ge-formula-box ge-anim"><span class="ge-formula-label">Formula</span><code>SV = EV - PV</code></div><p>Where:</p><ul><li><strong><a href="/en/earned-value/definitions/earned-value">EV</a></strong> = Budgeted Cost of Work Performed. The value of work actually completed.</li><li><strong><a href="/en/earned-value/definitions/planned-value">PV</a></strong> = Budgeted Cost of Work Scheduled. The value of work that should be complete by now, per your baseline programme.</li></ul><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>SV Result</th><th>Meaning</th><th>What To Do</th></tr></thead><tbody><tr><td>SV > 0</td><td>Ahead of programme</td><td>Verify it's real progress, not front-loaded activities</td></tr><tr><td>SV = 0</td><td>Exactly on programme</td><td>Enjoy the moment. It won't last.</td></tr><tr><td>SV < 0</td><td>Behind programme</td><td>Investigate root cause. Acceleration? Re-sequence?</td></tr></tbody></table></div><p>The result is always in currency units (pounds). SV = -£1.3M doesn't mean you're £1.3M over budget. It means you're behind schedule by a quantity of work that was budgeted at £1.3M. The distinction matters.</p><h2 id="how-sv-works-visually">How SV Works Visually</h2><pre class="ge-ascii-diagram ge-anim"> SCHEDULE VARIANCE – EV vs PV at Month 8 ============================================ £M | 10┤ ┌──────────┐ | │ │ 9┤ │ │ | │ PV │ 8┤ ┌──────────┐ │ £8.4M │ | │ │ │ (should │ 7┤ │ EV │ │ have │ | │ £7.1M │ │ done) │ 6┤ │ (what │ │ │ | │ we did) │ │ │ 5┤ │ │ │ │ | │ │ │ │ 4┤ │ │ │ │ | │ │ │ │ 3┤ │ │ │ │ | │ │ │ │ 2┤ │ │ │ │ | │ │ │ │ 1┤ │ │ │ │ | │ │ │ │ 0┼─────────────────┴──────────┴───────┴──────────┴── EV PV SV = EV - PV = £7.1M - £8.4M = -£1.3M ────────────────────────────────────── BEHIND PROGRAMME by £1.3M worth of work The gap between the bars = schedule variance PV is taller = we planned to be further ahead</pre><p>That -£1.3M gap represents work that should be in the ground but isn't. On this project, it might be a delayed piling rig, a late design approval, or a compensation event that's disrupted the programme. SV tells you there's a problem. It doesn't tell you why.</p><h2 id="the-convergence-problem-svs-fatal-flaw">The Convergence Problem, SV's Fatal Flaw</h2><p>Here's the thing nobody tells you when they introduce SV. It lies to you at the end of the project.</p><p>As a project approaches completion, EV converges towards <a href="/en/earned-value/definitions/budget-at-completion">BAC</a> (the total budget). PV also converges towards BAC. So SV converges towards zero, regardless of whether the project is on time. A project that finishes 6 months late will still show SV = 0 at completion, because all the planned work has eventually been done and all the budgeted work has been completed.</p><pre class="ge-ascii-diagram ge-anim"> SV CONVERGENCE PROBLEM ============================================= SV (£) | +1M ┤ ╱╲ Ahead | ╱ ╲ 0 ┤──╱──╱────╲─────────────────── ← SV always ends here | ╱ ╲ ╱ even if 6 months late! -1M ┤ ╲ ╱ | ╲ ╱ Behind -2M ┤ ╲___╱ | └────┬─────┬─────┬─────┬─────┬── Time 20% 40% 60% 80% 100% SV is MOST USEFUL in the first half (0-50% complete) SV is MISLEADING in the second half (50-100%) SV is USELESS at completion (always = 0) SOLUTION: Use SV(t) – schedule variance in time units See: earned schedule and SV(t)</pre><p>This is why the <a href="/en/earned-value/definitions/earned-schedule">Earned Schedule</a> extension was developed. <a href="/en/earned-value/definitions/schedule-variance-time">SV(t)</a> measures schedule variance in time units, not cost units, and doesn't converge to zero. On any project past 60% complete, I'd recommend using SV(t) alongside SV. Before 60%, traditional SV is fine.</p><h2 id="worked-example-20m-flood-defence-at-month-8">Worked Example: £20M Flood Defence at Month 8</h2><span class="ge-worked-label">Worked Example</span><div class="ge-callout ge-anim"><p><strong>Scenario:</strong> A £20M NEC4 Option C flood defence scheme in Cumbria. The project started in January 2025 with a 16-month programme. At the end of month 8 (August 2025), the commercial team runs the monthly EVM analysis.</p><p><strong>The baseline (from Accepted Programme):</strong></p><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>Month</th><th>Cumulative PV</th></tr></thead><tbody><tr><td>4</td><td>£4,200,000</td></tr><tr><td>6</td><td>£6,800,000</td></tr><tr><td>8</td><td>£8,400,000</td></tr><tr><td>10</td><td>£11,200,000</td></tr><tr><td>12</td><td>£15,000,000</td></tr><tr><td>16</td><td>£20,000,000 (BAC)</td></tr></tbody></table></div><p><strong>Month 8 actuals:</strong></p><ul><li>Physical progress measured using <a href="/en/earned-value/definitions/weighted-milestones">weighted milestones</a> across 6 packages</li><li>EV = £7,100,000</li><li>PV = £8,400,000 (from baseline)</li></ul><p><strong>Schedule Variance:</strong></p><ul><li>SV = £7,100,000 - £8,400,000 = <strong>-£1,300,000</strong></li><li><a href="/en/earned-value/definitions/schedule-variance-percentage">SV%</a> = -£1,300,000 / £8,400,000 = <strong>-15.5%</strong></li><li><a href="/en/earned-value/definitions/schedule-performance-index">SPI</a> = £7,100,000 / £8,400,000 = <strong>0.845</strong></li></ul><p><strong>What this means:</strong> The project has completed £1.3M less work than planned. At SPI = 0.845, for every £1 of planned progress, only £0.85 is being achieved. That's a significant schedule shortfall.</p><p><strong>Root cause analysis:</strong></p><ul><li>Sheet piling package: 3 weeks behind due to unexpected rock at toe level (potential <a href="/en/earned-value/definitions/compensation-event">compensation event</a> under clause 60.1(12), physical conditions)</li><li>Concrete works: 1 week behind, labour shortage following subcontractor insolvency</li><li>Earthworks: on programme</li></ul><p><strong>Action:</strong> The sheet piling delay is a legitimate CE. If accepted, the baseline adjusts, PV shifts, and SV improves. The concrete delay is Contractor risk, acceleration needed.</p></div><h2 id="common-mistakes">Common Mistakes</h2><ol><li><strong>Interpreting SV as a cost figure.</strong> SV = -£1.3M doesn't mean you're overspending by £1.3M. It means you're behind schedule by £1.3M worth of work. You might be perfectly on budget but just haven't got the work done yet. Cost performance is measured by <a href="/en/earned-value/definitions/cost-variance">CV</a>, not SV.</li><li><strong>Using SV alone past 60% complete.</strong> Once you're in the second half of the project, SV starts converging towards zero. A project that's badly behind will show an improving SV simply because EV is catching up to BAC. Supplement with <a href="/en/earned-value/definitions/schedule-variance-time">SV(t)</a> for an honest picture.</li><li><strong>Ignoring the sign of SV.</strong> Positive SV isn't always good news. If EV is running ahead of PV because the team is front-loading easy work to make progress look healthy, the underlying critical path might still be behind. Check which activities are driving the positive variance.</li><li><strong>Not decomposing SV to package level.</strong> A project-level SV of -£1.3M could be one package at -£2M and another at +£700K. The aggregate number masks opposite problems in different parts of the project. Always break SV down by <a href="/en/earned-value/definitions/control-account">control account</a>.</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>Why is schedule variance measured in pounds instead of time?</h3><p>Because EV and PV are both measured in pounds. SV = EV - PV, and since both inputs are currency values, the output is too. It's a legitimate criticism of traditional EVM, measuring schedule performance in cost units isn't intuitive. That's exactly why <a href="/en/earned-value/definitions/earned-schedule">Earned Schedule</a> was developed. SV(t) gives you the same insight but in weeks or months, which is what planners and project managers actually care about.</p><h3>What's a good SV threshold for triggering a recovery plan?</h3><p>There's no universal answer, but most UK contractors I've worked with use SV% as the trigger. Anything beyond -10% gets a yellow flag (investigate). Beyond -20% gets a red flag (mandatory recovery plan within two weeks). The actual thresholds should be set during baseline approval and documented in the project controls procedures.</p><h3>Does SV work on NEC4 Option A differently than Option C?</h3><p>The formula is identical. The difference is in how PV is derived. On Option A, PV comes from the priced activity schedule mapped to the Accepted Programme. On Option C, PV comes from the Defined Cost allocation against the Accepted Programme. The maths is the same; the source data differs.</p><h3>Can SV be positive even when the project is behind on the critical path?</h3><p>Yes. Absolutely. This is one of the most dangerous misreadings in EVM. If non-critical activities are ahead of schedule but the critical path is behind, overall SV can be positive while the project is actually slipping on completion date. Always check SV against the critical path, not just the aggregate.</p></article></div>