How to find your baseline monthly spending, the number every other plan depends on

Your baseline is what a normal month costs, with nothing unusual in it and nothing left out, and it is the number every other plan is built on. Take six months of spending, remove the transfers between your own accounts and the one-off events, average what remains, and add the annual bills and the irregular costs back as monthly shares. The result is a single figure, $4,320 in the worked example, that sizes the emergency fund, sets the floor for irregular income, and turns income into a savings rate. A household that knows its baseline can answer "how long could we last" and "how much are we keeping" in one line each; one that does not is guessing at both.

Why the raw monthly total is not the baseline

Any single month's total is the baseline plus whatever happened that month. A car repair, a wedding gift, an annual insurance premium, and a vacation all land in some month, and the month they land in reads high while the months around it read low. Averaging six raw months blends the events in, which is better than one month but still wrong in a way that depends on which events happened to fall in the window.

The baseline separates the two. The regular months are averaged with the events removed, and the events that recur, the annual premium, the car's repairs over a year, come back in as shares, so that the figure describes a month that includes its fair portion of the lumps without any actual lump in it.

Find it in five steps

1. Total six months of spending from every account, with the transfers between your own accounts and the card payments removed, so nothing is counted twice.
2. Pull out the one-off events: a repair, a gift, a trip, a deposit, an annual bill. Note each with its amount and whether it recurs.
3. Average the six adjusted months. That is the regular baseline.
4. Add back the recurring lumps as monthly shares: each annual bill divided by twelve, and the irregular costs, car repairs and the like, at two years of history divided by 24.
5. Write the figure down with its date. It is revised once a year or when the household changes.

A worked example, six uneven months

The raw average is $4,553 and the adjusted average is $4,150. Two lumps recur and come back as shares: the insurance at $720 a year is $60 a month, and the car's repairs at $2,580 over two years are $108 a month. The baseline is $4,150 plus $60 plus $108, or $4,318, rounded to $4,320.

The raw average was high by about $230 because the six months happened to contain a large repair and the premium; a different six months might have contained neither and read $400 low. The baseline reads the same whichever six months are chosen, which is what makes it a number worth writing down.

What the baseline is used for

• The emergency fund. Three to six months of essentials is the usual target, and the essentials are the baseline with the wants removed. A household with a $4,320 baseline and $3,100 of essentials has a three-month target of $9,300; see How to build an emergency fund inside a monthly budget.
• The income floor. For irregular income, the baseline is the month the budget is set to, and the buffer's job is to pay it every month; see How to budget on irregular or variable income.
• The savings rate. Take-home income minus the baseline, divided by income, is what the household keeps in a normal month. At $4,900 of income, $580 is kept, or 12%, and that figure is honest because the baseline already contains the lumps.
• The runway. Savings divided by the baseline is how many months the household could last with no income, which is the question the emergency fund answers in reverse.

Keep it current

The baseline drifts as rent rises, a child arrives, or a car is paid off. Recompute it once a year from the latest six months, and whenever a fixed cost changes by more than a few percent. Each recomputation resizes the emergency fund target and the savings rate, and a baseline that has risen without the household noticing is the usual reason a savings rate has quietly fallen.

Common mistakes

• Using one month. It is the baseline plus that month's events, and you cannot tell which is which.
• Leaving the transfers in. Savings moved to another account is not spending, and a card payment is not a second purchase.
• Removing the lumps and not adding them back. The baseline then describes a month with no insurance and no repairs, which is not a month anyone has.
• Removing every large item as a one-off. The grocery run and the utility bill are large and regular; only the events leave.
• Never revising it. A baseline from two years ago is a different household's number.
• Comparing it to gross income. The savings rate is take-home minus the baseline, over take-home.

Common questions

What is baseline spending? The cost of a normal month with nothing unusual in it and the recurring lumps included as monthly shares. It is found by averaging six months with the one-off events removed and adding back the annual bills and the irregular costs as shares. It is the figure the emergency fund, the income floor, and the savings rate are computed from.

How is it different from my budget? The budget is the plan, category by category, for the month ahead. The baseline is the measured cost of a typical month, as one number. A budget whose total is far from the baseline is a budget built on wishes, and the baseline is the check.

What counts as a one-off? An expense that will not recur in the next six months at that size: a repair, a deposit, a gift, a trip, a medical bill. Annual bills are removed from the month they land and added back as a twelfth; irregular costs that recur in aggregate, like car repairs, come back as a two-year share.

How much should my baseline be? Whatever six months of your own transactions produce; there is no external right number. The figure that matters is the baseline against take-home income, which is the savings rate, and that is the number to work on.

Should the baseline include savings transfers? No. It is spending. The transfer to savings is what is left after the baseline, and it is measured by the savings rate, not counted as a cost.

How Zypper handles this

Zypper gives you the six months and the lumps in one view. The cash flow page charts income against spending over any period you choose, this month, last quarter, or the year, with movements between your own accounts left out by default, so the six-month total is read rather than assembled, and grouping by category shows which rows carried the one-off events. The recurring page lists every annual bill with its amount, which is the list of lumps to add back as shares, and a category budgeted Every year shows its Monthly equivalent in the budget. The month's total against income sits on the budget page as Spent this month, which is the baseline check in miniature. See Cash flow, Recurring transactions and bill tracking, and Creating your budget for the details, or get started with Zypper to read your own six months.