We've seen a lot of clever workarounds in Excel over the years, but this two-axis interpolation engine from a Reddit engineer stands out as genuinely useful. It solves a pain point that mechanical and HVAC professionals know well: extracting precise values from performance maps, pump curves, or fan curves without manually eyeballing a printed graph. The author built a compact, LAMBDA-based tool that interpolates across two axes at once, and they've shared it for testing. Our take is simple: this is the kind of practical, human-focused innovation that makes legacy spreadsheets feel less like relics and more like a platform worth reinvesting in.
What makes this tool noteworthy isn't the complexity of the formula, though the nested LAMBDA functions and MATCH/INDEX logic are impressive, it's the intent behind it. The engineer recognized that traditional spreadsheets force users to either accept rough approximations or build cumbersome lookup tables. Their solution stitches together multiple interpolations to find a point where two variables converge, a process that previously demanded either specialized software or manual measurement (they mention using AutoCAD to measure graph displacement). By packaging that logic into a reusable formula, they've turned a tedious task into a repeatable, transparent calculation. For anyone working with pump curves or fan performance data, that's not just a time-saver, it's a reduction in error risk.
From a broader perspective, this tool demonstrates a shift in how engineers and analysts can think about spreadsheets. The author didn't wait for a vendor to add a "two-axis interpolation" feature; they reached into Excel's existing toolset, LAMBDA, MATCH, INDEX, IFERROR, and built what they needed. That's the progressive spirit we like to see: using the tools at hand to create something that feels like a native capability. It also underscores a truth that's often overlooked: the most transformative spreadsheet innovations aren't always about flashy new features. Sometimes, they're about giving users the power to define their own logic, clearly and without black-box complexity.
We'd encourage anyone who works with two-axis data to test this tool and give feedback. The formula is shared openly, the logic is documented, and the engineer is clearly open to refinement. That's how good tools get better, not through hype, but through real-world use and honest critique. If you've ever spent twenty minutes squinting at a pump curve, you already know why this matters. Now it's up to the community to push it further.