What Is Level of Effort (LOE) in Earned Value?

<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="#why-ev-always-equals-pv-for-loe">Why EV Always Equals PV for LOE</a></li><li><a href="#worked-example-site-supervision-at-45k-per-month">Worked Example: Site Supervision at £45K per Month</a></li><li><a href="#why-loe-should-be-capped-at-15-to-20-of-bac">Why LOE Should Be Capped at 15 to 20% of BAC</a></li><li><a href="#what-belongs-in-loe-and-what-doesnt">What Belongs in LOE (and What Doesn't)</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>Level of effort is work measured by the passage of time, not by any tangible output. The site security guard has been there for 6 months of a 12-month contract, so we say that work package is 50% complete. It doesn't matter whether security was brilliant or abysmal. Time passed. EV was earned. That's LOE. </p><p><strong>LOE Formula: EV = PV (always)</strong></p><p>Because <a href="/en/earned-value/definitions/earned-value">earned value</a> equals <a href="/en/earned-value/definitions/planned-value">planned value</a> by definition, LOE work packages produce an <a href="/en/earned-value/definitions/schedule-performance-index">SPI</a> of exactly 1.0 and a schedule variance of exactly zero. Always. Regardless of what's actually happening. That single fact makes LOE the most dangerous <a href="/en/earned-value/definitions/earned-value-technique">earned value technique</a> in your toolkit. </p><p>This term is part of the <a href="/en/earned-value/definitions">earned value definitions glossary</a>. For the formula reference, see the <a href="/en/earned-value/formulas">earned value formulas page</a>. </p><h2 id="why-ev-always-equals-pv-for-loe">Why EV Always Equals PV for LOE</h2><p>It's not a simplification. It's a definitional truth. </p><p>For <a href="/en/earned-value/definitions/discrete-effort">discrete effort</a>, you measure physical output: piles installed, concrete poured, cable pulled. The earned value might be ahead or behind plan. For LOE, there's no physical output to measure. The only proxy for progress is time elapsed. And time elapsed is, by definition, exactly what was planned to have elapsed. </p><pre class="ge-ascii-diagram ge-anim"> LOE vs DISCRETE EFFORT – EV Profiles Over 12 Months DISCRETE EFFORT (e.g., piling package): EV PV ─ ─ ─ (planned) (£) EV ───── (actual) 100%│ ─ ─ ─ ─ ─ ─ ─ │ ─ ─ ──────── │ ─ ─ ──── │ ─ ──── ← Gap = Schedule Variance │ ─ ── (EV can differ from PV) │─ ── 0% │── └──┬──┬──┬──┬──┬──┬──┬──┬──┬──┬──┬── 1 2 3 4 5 6 7 8 9 10 11 12 SPI varies: 0.82, 0.91, 0.88, 0.94, 1.01. USEFUL – tells you if work is ahead or behind. LEVEL OF EFFORT (e.g., site supervision): EV PV = EV (always identical) (£) 100%│ ── │ ── │ ── │ ── │ ── ← No gap. Ever. │ ── EV = PV by definition. │ ── 0% │── └──┬──┬──┬──┬──┬──┬──┬──┬──┬──┬──┬── 1 2 3 4 5 6 7 8 9 10 11 12 SPI = 1.00 every single month. USELESS for schedule performance. Only CPI can flag cost issues. </pre><p>The discrete effort package generates a schedule variance that tells you something. The LOE package generates nothing. It's invisible to your schedule warning system. </p><h2 id="worked-example-site-supervision-at-45k-per-month">Worked Example: Site Supervision at £45K per Month</h2><span class="ge-worked-label">Worked Example</span><div class="ge-callout ge-anim"><p><strong>Scenario:</strong> £25M rail electrification project, NEC4 Option C. 24-month programme. Site supervision is a separate work package budgeted at £45,000 per month = £1,080,000 total <a href="/en/earned-value/definitions/budget-at-completion">BAC</a>.</p><br><p><strong>Month 8 reporting:</strong></p><br><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>Metric</th><th>Value</th><th>Calculation</th></tr></thead><tbody><tr><td>PV (cumulative, month 8)</td><td>£360,000</td><td>8/24 x £1,080,000</td></tr><tr><td>EV (cumulative, month 8)</td><td>£360,000</td><td>= PV (LOE rule)</td></tr><tr><td>AC (cumulative, month 8)</td><td>£410,000</td><td>Actual invoices from supervision provider</td></tr><tr><td>SV</td><td>£0</td><td>EV - PV = £360,000 - £360,000</td></tr><tr><td>SPI</td><td>1.00</td><td>EV / PV = £360,000 / £360,000</td></tr><tr><td>CV</td><td>-£50,000</td><td>EV - AC = £360,000 - £410,000</td></tr><tr><td>CPI</td><td>0.88</td><td>EV / AC = £360,000 / £410,000</td></tr></tbody></table></div><br><p>SPI says everything is on track. It's lying. SPI can't tell you anything about LOE work.</p><br><p>CPI says you're overspending by 12%. That's real. The supervision provider brought in an additional senior supervisor for 3 months (at £6,250/month extra) to cover a complex possession sequence. Nobody updated the budget.</p><br><p><strong>The hidden problem:</strong> If site supervision runs at CPI 0.88 for the full 24 months, the final cost will be £1,080,000 / 0.88 = £1,227,273. That's £147,273 over budget. On an Option C contract, that overspend erodes the contractor's share of any gain, or deepens their share of the pain.</p><br><p><strong>What should have happened:</strong> The additional supervisor was a Client instruction (the possession sequence was changed by the railway operator). This should have been notified as a compensation event. The budget should have increased by the agreed cost of the additional resource. Instead, the team absorbed it, the CPI dropped, and nobody questioned it because "prelims always overrun."</p><br><p>That's not prelims overrunning. That's a CE hiding in the LOE.</p></div><h2 id="why-loe-should-be-capped-at-15-to-20-of-bac">Why LOE Should Be Capped at 15 to 20% of BAC</h2><p>This isn't an arbitrary rule. It's mathematical self-defence. </p><p>The more LOE in your project, the less sensitive your aggregate SPI becomes. Because LOE always reports SPI = 1.0, it dilutes any schedule problems in the discrete portion. </p><p>Here's the maths. Say your project has 30% LOE and 70% discrete effort. The discrete portion is running at SPI = 0.80 (serious problem, 20% behind schedule). What does the aggregate SPI show? </p><p>Aggregate SPI = (0.70 x 0.80) + (0.30 x 1.00) = 0.56 + 0.30 = <strong>0.86</strong></p><p>Now push LOE to 40%: </p><p>Aggregate SPI = (0.60 x 0.80) + (0.40 x 1.00) = 0.48 + 0.40 = <strong>0.88</strong></p><p>And 50%: </p><p>Aggregate SPI = (0.50 x 0.80) + (0.50 x 1.00) = 0.40 + 0.50 = <strong>0.90</strong></p><p>With 50% LOE, a discrete SPI of 0.80 (a project in serious trouble) reports an aggregate SPI of 0.90 (looks manageable). The LOE is literally hiding the problem from your dashboard. </p><p>I worked on a £60M programme where the commercial director couldn't understand why the project was three months late when SPI was 0.93. We dug into the numbers. LOE was 38% of BAC. The discrete-only SPI was 0.82. The project had been signalling distress for months, but the LOE was anaesthetising the metrics. </p><p>Cap LOE at 15 to 20%. Fight for it. If someone tells you prelims "have to be" LOE, challenge that. Site setup and mobilisation can be measured with milestones. Temporary works can be measured with units. The only genuinely LOE activities are ongoing, steady-state support functions: security, welfare, general site management. </p><h2 id="what-belongs-in-loe-and-what-doesnt">What Belongs in LOE (and What Doesn't)</h2><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>Genuinely LOE</th><th>Often Classified as LOE (But Shouldn't Be)</th></tr></thead><tbody><tr><td>Site security</td><td>Design coordination (use milestones)</td></tr><tr><td>Welfare facilities maintenance</td><td>Site setup/mobilisation (use milestones)</td></tr><tr><td>General site management</td><td>Temporary works (use units or milestones)</td></tr><tr><td>Environmental monitoring</td><td>Testing and commissioning (use milestones)</td></tr><tr><td>Programme management overhead</td><td>Health and safety audits (use <a href="/en/earned-value/definitions/apportioned-effort">apportioned effort</a>)</td></tr></tbody></table></div><h2 id="common-mistakes">Common Mistakes</h2><ol><li><strong>Classifying everything you can't easily measure as LOE</strong>: Lazy categorisation is the number one reason LOE creeps above 20%. If a work package produces any kind of deliverable or milestone, it's discrete effort. LOE is the last resort, not the default.</li><li><strong>Ignoring CPI on LOE packages</strong>: Because SPI is useless for LOE, the only performance signal is <a href="/en/earned-value/definitions/cost-performance-index">CPI</a>. Most teams don't look at CPI on prelims or site management packages because "it's just a time charge." But a CPI of 0.85 on a £2.5M prelims budget means £441,000 over budget at completion. That's real money.</li><li><strong>Not separating LOE from discrete in reporting</strong>: Report aggregate metrics, but also report discrete-only SPI and CPI alongside them. The discrete-only numbers show the true health of productive work. If your reporting tool can't filter by <a href="/en/earned-value/definitions/earned-value-technique">earned value technique</a>, it's not fit for purpose.</li><li><strong>Forgetting that LOE hides compensation events</strong>: On NEC4 contracts, changes to supervision requirements, welfare provision, or security needs can all be compensation events. Because LOE packages always show SPI = 1.0, cost overruns in these packages don't trigger the same alarm bells. You have to actively monitor LOE CPI to catch them.</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 does EV equal PV for level of effort?</h3><p>Because there's no independent way to measure output. LOE work doesn't produce countable deliverables. The only measure of "progress" is how much time has passed relative to the total duration. Since planned value is also calculated based on time (the budget spread over the planned duration), the two are always identical. It's a mathematical identity, not a measurement. </p><h3>Can level of effort have a cost variance?</h3><p>Yes. LOE always has SV = 0 and SPI = 1.0, but CPI and cost variance work normally. If your supervision package is budgeted at £40K per month but you're actually spending £46K, the <a href="/en/earned-value/definitions/cost-variance">cost variance</a> will show a negative number and CPI will be below 1.0. This is your only warning signal for LOE packages. </p><h3>What percentage of a construction project should be LOE?</h3><p>Industry best practice is no more than 15 to 20% of <a href="/en/earned-value/definitions/budget-at-completion">BAC</a>. On most UK construction projects, <a href="/en/earned-value/definitions/preliminaries">preliminaries</a> run between 8% and 15% of contract value, and these are the primary LOE candidates. If your LOE exceeds 25%, audit your work package classifications. Something that should be discrete has almost certainly been miscategorised. </p><h3>Is LOE the same as overhead?</h3><p>Not quite. LOE is an earned value technique, a method of measurement. Overhead is a cost category. Site overheads (prelims) are often measured using LOE, but not all LOE is overhead. A project management support function could be LOE without being an overhead in the accounting sense. And some overheads (temporary works, site establishment) should be measured as discrete effort, not LOE. </p></article></div>