What this calculator does

It splits one month's take-home across named envelopes, in amounts or percentages, and keeps count of what is still unallocated. That is the entire mechanism, and it predates every budgeting app by about a century: give every euro a name before the month starts spending it for you. Start from a preset split or build your own from a blank page.

How this calculator works

It splits your monthly take-home across the envelopes you set, adds them up, and shows what is left to give out. It sets the limits you choose; it does not tell you what to spend, and it does not hold the line for you. Whether a limit sticks depends on how you hold the money, and the guide covers that. The preset splits are starting points, not rules. The 50/30/20 split is a US rule of thumb, and it breaks the moment your rent runs past half your pay, which is common across European cities. So treat every percentage as a suggestion you change. There is no forecast here and no investment return. The savings envelope is this month's slice, not a projection of what it grows into.

When to use it (and when not)

Use it at the start of the month, or right after a pay rise, while the new money is still visible and has not yet dissolved into lifestyle. It also settles the 'where does it all go' conversation in roughly four minutes, which is cheaper than most versions of that conversation. Do not treat the preset percentages as targets: rents differ, cities differ, and a split that ignores your rent is a fantasy with good branding. Set envelopes you can actually obey.