Spreadsheet Day - Celebrate the grid that changed everything
October 17 marks a quiet revolution. On this day in 1979, VisiCalc shipped—the first electronic spreadsheet—and suddenly, anyone with a computer could model ideas, track budgets, and make decisions faster than ever before. That simple grid of rows and columns became the backbone of modern business, education, and creativity. How Did Spreadsheet Day Begin? Spreadsheet Day was created in 2010 by Excel MVP Debra Dalgleish, known worldwide for her work at Contextures. Her goal was simple: celebrate the spreadsheet’s impact and the vibrant community around it. She chose October 17 to honor VisiCalc’s release—the moment spreadsheets went digital and changed everything. A Quick Look Back Before spreadsheets, recalculating a budget meant erasing and rewriting by hand. VisiCalc changed that overnight, and Excel carried the torch—bringing charts, formulas, and collaboration to millions. Over four decades, spreadsheets have evolved from static tables to dynamic engines for analysis and storytelling. They’ve powered breakthroughs in science, finance, and even art. Beyond the features, spreadsheets represent something bigger: empowerment. They give anyone the ability to turn raw data into insight. That’s why Spreadsheet Day isn’t just about software—it’s about the people who use it to solve problems every day. Debra’s vision sparked a tradition that now spans the globe. Educators, analysts, and enthusiasts join in each year to share tips, stories, and appreciation for a tool that empowers millions—a reminder that community matters as much as technology. Meet the Spreadsheet Champions Celebrate Spreadsheet Day with a sneak peek at Spreadsheet Champions, a documentary that goes beyond formulas to tell a human story. This film follows six students from around the world as they compete in Microsoft’s Excel challenge. Each brings unique hopes and struggles—whether it’s De La Paix in Cameroon aiming to make his family proud, Carmina in Guatemala finding refuge in math, or Mason in the U.S. balancing his love for spreadsheets with quirky hobbies. Alongside Alkmini from Greece, Nam from Vietnam, and Braydon from Australia, these young competitors reveal how mastering a spreadsheet can unlock confidence, opportunity, and even friendship. It’s a celebration of resilience, creativity, and the influence of spreadsheets in shaping lives today. Watch the trailer below: Why We Celebrate Spreadsheet Day isn’t about nostalgia—it’s about recognizing the creativity and problem‑solving that spreadsheets unlock. Every chart that clarifies a decision, every formula that saves a late night, every model that helps a team plan better—that’s the legacy we’re celebrating. Today, spreadsheets are everywhere: in classrooms, boardrooms, and even living rooms. They’ve helped launch companies, plan weddings, analyze sports stats, and map out personal goals. Spreadsheet Day is our chance to pause and appreciate the tool that makes all of that possible. Share Your Story We want to hear from you! What’s your favorite spreadsheet memory? What tip or trick changed the game for you? Post your story on social with #SpreadsheetDay, or drop it in the comments below. We’ll be reading and sharing some of our favorites. Your experience might inspire someone else to try something new. Happy Spreadsheet Day! Join the conversation with #SpreadsheetDay, and let’s keep building the future—one cell at a time.An Inside Look at Copilot in Excel
When you ask Copilot in Excel to “add a drop-down menu to this column” or “fix this formula in the team inventory tracker,” behind the scenes, Copilot reasons about your intent, picks and applies the right Excel features, and then edits the workbook. This can feel straight forward for some tasks but, now imagine you’re a Finance professional asking Copilot in Excel: “What’s broken in this valuation model, and how does fixing it change the outcome?” This is not a simple single formula request; it is an end-to-end finance workflow. To tackle it, Copilot needs to inspect the workbook, understand the finance specific business question, identify assumptions and formulas that may be wrong, correct the model, recalculate outputs, and explain the impact in a way a finance professional can trust. A good answer is not just “here is the new result.” A good answer is a clear, auditable explanation of what changed, why it changed, and its impact on values in the model. That kind of prompt is what we think of as an L4 workflow: an open-ended business problem that requires multiple steps, multiple Excel capabilities, and domain judgment. It is also a great way to understand why evals matter. To provide a great response to this question, many different operations and features need to ladder together successfully to deliver the final result. So how do we make sure every part comes together to solve the customer's intent? This is the job of our evaluation system, aka our "evals.” We’ll provide a brief tour through how we think about evals in Excel: what they are, how we organize them, the benchmarks they produce, and how we use these results to make Copilot in Excel better every week. What are evals, and why do we have them? An eval is a repeatable test of Copilot quality. We give Copilot in Excel a task and a starting workbook, let it do its work, and then grade the output against a series of checks and rubrics. These checks go beyond just confirming whether a value is correct. They also assess whether the workbook is usable, auditable, well- formatted, and aligns to Excel best practices. We evaluate more than the final workbook output. For agentic workflows, the path to the result matters too: what steps the agent took, which tools it called, how many turns it needed, how long the experience took end to end, and more. Looking at that trajectory helps give us a clearer measurement of whether the agent is becoming more accurate, capable, and efficient at how it reaches the desired result. Evals measure Copilot quality and are how we move from “this feels better” to “this is measurably better.” A prompt tweak, model upgrade, or a new tool can improve one customer intents while quietly making another worse. Our evals help us catch those regressions before they reach customers, as well as quantify improvements from new capabilities and find quality gaps early enough to prioritize fixes. How we organize our evals Excel is used by millions to complete a wide range of work: tracking lists, analyzing sales, managing operations, building financial models, planning budgets, and much more. Even the same task can have different expected answers whether you’re a finance professional or a small business owner. To measure Copilot in Excel quality reliably, we ensure our eval cases represent the breadth of customer workflows and all the different flavors of spreadsheets they use. We organize eval cases across several dimensions. Complexity is one of the most important dimensions, because it lets us test the building blocks separately while also testing the full customer workflow. We also categorize cases by customer role, domain, workbook characteristics, Excel feature usage, and more, so our benchmarks reflect the breadth and depth of real Excel work. Complexity: L1 through L4 We think about task complexity as a ladder. At the bottom are atomic actions and individual features. Higher up are multi-step tasks. At the top are open-ended workflows that sound more like business problems. The important point is that an L4 workflow is only as strong as the L1, L2, and L3 capabilities underneath it. L4 workflows: solving an open-ended business problem, such as debugging a valuation model or determining how much cash is available for debt service. L3 multi-step tasks: combining features to complete a defined goal, such as creating a sales summary worksheet or building a cash-flow bridge. L2 feature usage: using an Excel capability correctly, such as creating a PivotTable, applying conditional formatting, building a chart, or using formula auditing. L1 actions: single operations such as inserting a row, editing a formula, formatting a cell, or creating a label. Let’s go back to the valuation example at the start of the blog: “What’s broken in this valuation model, and how does fixing it change the outcome?” Copilot needs to break the work into several major steps: inspect the model structure, locate the key assumptions, audit the formulas, correct the calculation logic, compare the before-and-after outputs, and summarize the business impact. Each step sounds simple at the surface, but each depends on many smaller capabilities working reliably. Level What it means How it shows up in the valuation scenario L4: Workflow Solving an end-to-end business problem “What’s broken in this valuation model, and how does fixing it change the outcome?” L3: Multi-step task Composing multiple Excel capabilities to reach a goal Identify incorrect assumptions Correct formulas Recalculate outputs Quantify the impact L2: Feature usage Using one Excel capability correctly Apply formula auditing Update cross-sheet references Build comparison tables Document changes L1: Action Performing a single atomic operation on the grid Edit a formula Insert a table Format cells, values Write a label and notes Check cell reference Customer role and vertical domain What a good workbook looks like in Excel is often domain-specific. A formula that is acceptable in a general spreadsheet may not meet the bar for a finance model. A summary that works for a small business owner may not be enough for a consultant preparing a client deliverable for a large enterprise. That is why we build and review eval cases with domain-specific expectations in mind. We’ve worked closely with industry partners and customers to validate coverage, review input and output workbooks, and author grading rubrics and success criteria. Through these processes, we ensure our evals are realistic, aligned to expert human judgement, and reflect their taste and domain specific expertise. For example, we look at the shape of the workbook itself: number of sheets, workbook size, data density, formulas, tables, charts, and other Excel features. Real workbooks are rarely tidy single-tab examples. They can be large, messy, and full of context. Another example is our finance-specific rubrics for model structure, formula construction, auditability, and presentation quality. From categories to benchmarks Once we have categorized our eval cases, we curate them into benchmarks. Our goal here isn’t a single benchmark or a single number. Rather, we have different benchmarks for the different types of decisions we face while building Copilot in Excel. Some of our benchmarks provide broad coverage with an emphasis on comparability. Others target Excel-specific behaviors and customer workflows for specific feature areas or customer segments. Here is a subset of the benchmarks we use internally: Public benchmarks One public benchmark used by many spreadsheet products is SpreadsheetBench, a benchmark of spreadsheet tasks that provides broad coverage of common operations. Internally, we’ve further curated and validated subsets of this benchmark to adjust ambiguous queries, improve grader correctness, and improve signal to make results more easily applicable. However, we believe our internal benchmarks better reflect the type of work and expectations of Excel customers. Private benchmarks In addition to public benchmarks we maintain several internal benchmarks within the Excel team. Some examples include: RegressionBench helps us detect whether a change has broken something that used to work. CustomerBench focuses on matching production customer distributions across task complexity, domains, workbook shapes, and other dimensions. This provides an signal that mirrors customer usage. OfficeJSBench measures whether the operations Copilot generates to act on the workbook execute reliably and produce the intended result. FinanceBench is one of our deep and challenging vertical benchmarks focused on finance workflows and uses finance-specific rubrics for correctness, structure, and auditability. We developed FinanceBench with input and review from partners like Financial Modeling Institute (FMI), Microsoft Finance, and other finance professionals and customers. The collection of these benchmarks provides both broad and granular measurements on quality. They allow us to measure where the agent is strong, where it can improve, and whether a change has the intended impact on the customer experience. How eval results make Copilot in Excel better Evals are not just a reporting mechanism - they are deeply integrated into how we build the AI experience in Excel. Eval benchmarks help: Gate releases: Benchmark runs are part of how we decide whether a feature is ready to advance from our validation environments to customer availability. If evals detect issues or the improvement doesn’t show intend impact, the change does not move forward. Improve based on customer signals: When a customer conversation or signal reveals opportunity for improvement, we classify it and then create representative eval cases for it. We can then fix it and measure improvement in subsequent eval runs. Model training: We use rubrics and graders from evals to provide signal to tune models for spreadsheet work. Inform the right model for the job: Comparable benchmark results help us route tasks to models that balance quality, latency, and capability, to provide the best experience to customers. Over time, this creates a virtuous cycle: feedback and usage identify opportunities, evals quantify them, fixes and training address them, benchmarks confirm the win, and the next release starts from a higher bar. Why the hero scenario matters Coming back to the valuation prompt, the reason it matters is that it represents the kind of work people increasingly want Copilot in Excel to help with. They do not just want help inserting a chart or writing one formula. They want help completing meaningful work: understanding a model, finding an issue, improving the analysis, and making the result easier to trust. We can only deliver that L4 experience if the underlying layers are strong. Formula edits have to be correct, feature usage has to be reliable, multi-step plans have to stay coherent, and the final workbook has to be clear, complete, and auditable. That is why our eval system measures both the broad set of things people do in Excel and the deep workflows that matter most in demanding domains like finance.
