I made a spreadsheet where formulas also update backwards
Hello HN! I'm happy to release this project today. It's a bidirectional calculator (hence the name bidicalc). I've been obsessed with the idea of making a spreadsheet where you can update both inputs and outputs, instead of regular spreadsheets where you can only update inputs. Please let me know what you think! Especially if you find bugs or good example use cases.
I made a spreadsheet where formulas also update backwards launched on December 11, 2025 with 252 votes, #98 of 11,628 launches that month and more than 95% of that year's launches.
In plain words
Bidicalc is a spreadsheet tool that enables bidirectional formula updates. Unlike traditional spreadsheets where only inputs can be modified, this application allows users to change output values and have formulas automatically recalculate corresponding inputs. It's designed for anyone working with calculations who needs flexibility to work backwards from desired results to required inputs.
written from the facts on this page · September 2026
From the sources
A speadsheet where formulas also update backwards
Could it also work the other way? What if you could also change the output, and have the inputs be updated to match the formula? For the past few months I've been obsessed really curious about this idea. But there were so many questions: Ok, now let's just skip to the good part! Today I'm happy to introduce: Variables A simple number entered in a cell is a variable: 1.0 . It may be changed by the solver. Constant A number prefixed by a hash # is a constant. It will not be changed by the solver. Text Cells can be in text mode. To input text, wrap in double quotes: "Distance (km)" . A1 + A2 A1 + A2*(A3 - A1)^2 exp(A1) #A1 + H5 * #H6 cos(2*pi()) The result of formulas will be automatically…from victorpoughon.github.io
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