How we calculate your results

What data do we use?

All calculation amounts come from you: take-home income, expenses, accessible cash and the scenarios or reserve target you choose. We do not currently use city averages, C2ER, HUD, Census data or a tax engine. External reading linked in our guides provides context; it does not supply values to these calculations.

For a personal budget, include your share of bills and money you can use. For a shared budget, combine the included incomes and expenses, counting each amount once. Exclude credit limits, inaccessible assets and cash already committed elsewhere.

1. Your monthly budget

Use income after taxes and payroll deductions. Convert each income to a monthly average, then add the results:

• Weekly: amount × 52 ÷ 12.
• Every two weeks: amount × 26 ÷ 12.
• Twice a month: amount × 2.
• Monthly: amount unchanged.
• Annual: amount ÷ 12.

Monthly balance = monthly income − necessary expenses − flexible expenses. A negative balance is a shortfall. Include monthly shares of predictable annual bills, and do not subtract payroll deductions twice.

Illustration: $4,000 take-home income − $2,500 necessary expenses − $500 flexible expenses = $1,000 left each month. This does not account for any costs you omitted or extra savings contributions.

2. How long your savings could last

If all income stops: accessible cash ÷ total monthly expenses. The essentials-only scenario divides cash by necessary expenses instead. With income continuing and spending exceeding it, divide cash by the monthly shortfall.

Illustration: $6,000 cash and $3,000 monthly expenses gives 2 months without income. If income instead continues at $2,500, the $500 monthly shortfall gives 12 months. These are different scenarios, not competing answers.

If the relevant spending amount is zero, we show “Not calculable” rather than infinite months. If income covers spending, there is no monthly shortfall to use as a divisor; that does not guarantee your savings will never run out.

3. The effect of a pay cut

Income reduction room = the larger of zero and your monthly balance. This is a break-even limit at unchanged spending, not a recommended cut. An already negative budget has no additional room.

A percentage cut applies to the selected monthly take-home income, not gross salary or all household incomes. A dollar cut is a monthly reduction in that income. Other income entries stay unchanged. The reduction cannot exceed the selected income.

Illustration: a 20% cut to $3,000 take-home income removes $600 per month. With another $1,000 income and $3,000 spending, the new balance is $400. Choosing “necessary expenses only” removes all entered flexible spending; use it only if that reduction is realistic.

4. Your emergency fund and savings plan

Reserve target = necessary monthly expenses × chosen months. The remaining gap is the target minus accessible cash, with a minimum of zero. Your chosen target is not an official financial safety threshold.

With a positive planned contribution, divide the gap by that contribution and round up to a whole month. Contributions arrive at month-end; no interest or withdrawals are included. A zero contribution cannot close a positive gap. If the target is already met, the time is zero.

Illustration: $2,000 necessary expenses × 3 months = $6,000. With $1,500 cash, the gap is $4,500. Saving $150 each month takes 30 months under these assumptions.

Monthly improvement needed = the larger of zero and planned contribution − monthly balance. We can make this comparison only with a valid, complete budget. Income of $3,000, spending of $3,200 and a $500 contribution requires a $700 monthly improvement. Without complete income and expenses, the savings timeline is hypothetical. A plan fitting your entries does not verify unlisted bills or actual bank balances.

Necessary expenses must be above zero to calculate an expense-based reserve target. Target months must be above zero and no more than 120.

5. A large purchase or one-time bill

Cash after payment = accessible cash − one-time cost. If the cost exceeds cash, the funding gap is cost minus cash. With only cash and cost entered, we can show this cash comparison but cannot assess monthly sustainability or calculate runway.

With a complete budget and enough cash for the payment, we recalculate runway using the remaining cash and unchanged monthly spending. A valid reserve target also lets us show the gap below that target. We do not treat borrowing as negative cash or model financing payments.

Illustration: $8,000 cash − a $3,000 cost leaves $5,000. At $2,000 monthly spending, no-income runway falls from 4 to 2.5 months. If the chosen reserve target is $6,000, the payment leaves a $1,000 gap below it. These results describe the trade-off; they do not recommend buying.

The budget check shows one-time room above a reserve target only when the budget is not in deficit and a usable target exists. That amount is cash minus the target, with a minimum of zero.

Precision and limits

Money inputs accept up to two decimal places. Calculations retain precision before display; dollar amounts display cents and runway displays one decimal place. Savings-plan months round up, so a partial final month still requires another contribution. Rounded displays can differ slightly from calculations made using already rounded values.

Blank required amounts are not treated as zero. Invalid inputs prevent the affected result; a missing optional reserve target does not stop an otherwise complete monthly budget calculation.

Monthly averages do not model payday or bill dates. We do not predict illness, accidents, job loss, inflation, investment returns, tax changes or insurance coverage. Results depend on your entries and assume other conditions stay unchanged. There is no universal “safe” score or official paycheck-to-paycheck classification.

Your entries, saved drafts and reports

By default, entries remain in this tab’s memory and are not submitted to a budget server. Internal navigation keeps the shared budget; a refresh clears it unless you enabled device saving.

Device saving is optional and uses this browser profile. A saved draft can be restored on a later visit, and anyone with access to that profile may be able to read it. There is no account or cross-device sync.

“Stop saving and remove draft” removes the stored draft when browser storage is available, while keeping the current entries in memory. “Clear all my entries” also clears this tab’s budget and scenarios after confirmation. If removal fails, the interface explains how to retry or clear this site’s browser data. Downloaded reports are separate files and are not deleted by either action.