Cash Envelopes

The Cash Envelope Budget Split Calculator divides a fixed pool of cash across three spending envelopes -- Groceries, Fuel, and Misc -- using weights you assign to each category. The weights don't need to add up to 100%: the calculator normalizes them automatically, so entering 45/20/35 or 90/40/70 produces the identical three-way split, just derived from your relative priorities rather than an exact percentage. Cash this period is the dominant input by a wide margin -- raising the total pool raises every envelope's dollar amount proportionally and moves each of them more than any single weight adjustment does, since the total pool scales all three envelopes at once while a weight change only shifts the balance between them.

Raising the Groceries weight raises the Groceries envelope, but it simultaneously lowers the Fuel and Misc envelopes, because normalization means the three weights are always competing for shares of the same fixed total -- nothing here can add cash to the system, only reallocate it. What this does not account for: envelope categories not represented here (housing, subscriptions, savings), rollover of unspent cash from a prior period, or expenses that don't fit neatly into groceries, fuel, or misc.