Add inflows, subtract outflows, and check whether your cash holds the month. Accounting profit and available cash are different things — this calculator works with the second.
A profitable business can run out of cash. This happens when sales collect late and supplier payments fall fast. The calculator separates real inflows from collections (not from issued invoices) and real outflows (not accrued ones) to show what actually remains. It's a quick operational tool; for a 12-month projection with three scenarios, open the advanced simulator at /simuladores/flujo-caja.
Financial disclaimerIndicative result — not professional financial advice. Consult a specialist before making investment or credit decisions.
Period ending balance (initial cash + inflows − outflows), period net flow (inflows − outflows), and an alert when projected balance enters negative territory. It works on actual collections and payments, not on accruals.
Who it's for
For founders and SMB owners who need to quickly verify whether cash holds for a major purchase, extra payroll, or upfront payment. For operating managers closing the week or month with tight cash. For freelancers and consultants with variable collection terms.
When to use it
Before committing a large payment (seasonal inventory, supplier prepayment, annual insurance premium). When two wholesale customers ask to extend payment terms. At month close, to verify next month starts with the expected real cash. Before requesting a backup credit line.
When NOT to use it
Don't use it to present a formal business case: banks, investors, and committees ask for audited financial statements, not a manual calculation. Don't use it as a substitute for accounting: tax close and official reports need accounting software and an accountant. For monthly scenarios across three paths (base, conservative, aggressive), open the advanced simulator.
What data it needs
Initial cash
Available cash at the start of the period: operating bank balance plus petty cash. Don't include liquid investments you can't move within hours.
Inflows (period collections)
What actually hits the account in the period. If you invoiced $300,000 but collect $180,000, declare $180,000. An invoice issued but not collected is accrued revenue, not cash.
Outflows (period payments)
Effective payments: payroll, suppliers, rent, services, taxes, banking fees. Include prorated annual recurrences if they fall in this period.
Measurement period
Default is one month. You can adjust to a week, fortnight, or several months. Monthly granularity is the most common for SMBs; weekly works for tight-cash operations.
Formula
Ending balance = Initial cash + Inflows − Outflows. Period net flow = Inflows − Outflows. With $120,000 initial cash, $180,000 inflows, and $232,000 outflows, ending balance is $68,000 and net flow is −$52,000 — the business spent more than it collected that period, even with cash still positive.
How to interpret the result
Positive ending balance and negative net flow is an early signal: cash holds this month but you're burning it. If net flow stays negative, cash will run out — calculate how many months remain by dividing initial cash by absolute net flow. Negative ending balance means you need additional liquidity before the period ends: credit line, advance collection, expense cuts.
How this calculator was reviewed
What you'll see, what it prevents, and where you shouldn't trust it
Every flagship calculator ships with the same editorial structure: two hypothetical worked examples with numbers, the errors it helps you avoid, the model's declared limitations, and a visible financial disclaimer. The review is signed and dated.
Hypothetical case·Case A
A profitable business that nearly closes because it collected at 60 days and paid at 7
A distributor sells $480,000 MXN/month with 22% gross profit — profitable on paper. Average collection period: 60 days. Supplier payments: 7 days (supplier requires deposit). By month 3, the calculator shows inflows $480,000 (collections from month 1), outflows $480,000 (month 3 inventory payment) plus $96,000 fixed expenses: $96,000 deficit. Cumulative profit $317,000, but cash at zero. The decision: renegotiate terms with two wholesale customers to bring collection to 30 days, or secure a working capital line.
Illustrative figures. This example does not represent a real company or a financial recommendation.
Hypothetical case·Case B
A store with healthy cash that breaks during the seasonal peak from prepaid inventory
A gift store operates with $180,000 MXN initial cash, average monthly sales $220,000 and costs $165,000 — net flow +$55,000/month in normal months. For December, it buys $260,000 in inventory in October, but gift sales concentrate in December. The calculator projects: October ending balance $35,000; November $30,000; December sells $480,000 with immediate collection and ends the year at $375,000. Cash holds — barely. If December sales drop 20%, the store faces a deficit in November. Decision: backup credit line for 60 days.
Illustrative figures. This example does not represent a real company or a financial recommendation.
Common mistakes it helps you avoid
Things a team or decision-maker might assume that this calculator forces you to verify before closing the math.
Confusing sales with collections. An issued invoice is accounting revenue, not cash. The calculator separates the two so you see the gap between accrual and cash basis.
Forgetting recurring annual payments: insurance, domains, annually-paid software. Modeling only the monthly average misses the months they hit.
Not including VAT on outflows: passed-through VAT is paid to the tax authority monthly. Forgetting it distorts the ending balance by 10-16% depending on jurisdiction.
Treating profit as available cash. A profitable company can run out of liquidity if it grows fast and finances its customers. Profit and cash KPIs are different.
Model limitations
What the calculator does not do, and where you need a professional or a specialized tool.
Models a user-declared period (one or several months). For a 12-month projection with base/conservative/aggressive scenarios, open the cash flow simulator.
Does not predict demand. You declare the projected sales; the calculator runs the cash math on that projection.
Does not include country-specific tax rules. VAT, income tax, withholdings vary; the calculator asks for the net amounts you already know.
Does not replace formal accounting. For tax close and auditable reports, you need accounting software and an accountant.
When NOT to use this calculator
Do not use this calculator to present to a bank, investor, or board of directors. It's an operational pre-screening tool — useful to understand whether your next decision fits in your current cash, not to replace formal financial statements. For deep runway and pessimistic-scenario analysis, open the advanced cash flow simulator at /simuladores/flujo-caja.
Financial, tax, accounting and legal notice
The result is an informative estimate based on the data you enter. It does not constitute financial, tax, accounting, or legal advice. For decisions that affect taxes, financing, or wealth, validate the numbers with a certified professional in your jurisdiction.
Editorial review
Reviewed by the Simúlalo editorial team
This simulator was reviewed by the people listed below before being published. The review covers the declared formula, the model's assumptions, the explicit limitations, and the absence of unsupported financial claims.
They are part of the Simúlalo editorial team, focused on building financial tools that are clear, educational, and easy to interpret.
Last updated: ·We update this page when the methodology, sources used, or simulator structure change.
This tool uses standard financial formulas and user-supplied data. To explain concepts like rates, credit, risk, or cash flow we consult public and official sources (Banxico, SAT, CONDUSEF, CNBV, Banco de España, IFRS, BIS, among others). Simúlalo is not affiliated with, sponsored by, or endorsed by these institutions.
Frequently asked questions — cash flow
1Why can a profitable business run out of cash?
Because accounting profit measures accrued revenue (issued invoices) minus accrued expenses (period purchases), not real cash flows. If you collect at 60 days and pay at 7, a profitable company can operate three months with declining cash before running out of liquidity. The calculator works on actual collections and payments precisely to avoid that trap.
2What counts as an outflow and what doesn't?
Counts: actual supplier payments, payroll, rent, taxes, services, fees, interest. Doesn't count: depreciation (not a cash outflow), accounting amortization, payables not yet paid. Depreciation is an accounting expense that reduces profit but doesn't touch cash.
3How do I handle installment collections?
If a customer pays in three installments, declare each installment in the period you actually receive it. The calculator works on the moment of collection, not of invoicing. To visualize the sequence across several months, open the advanced simulator.
4Does the calculator factor VAT?
It works with the gross amounts you declare. If you collect prices with VAT, those are your gross inflows. VAT due to the tax authority enters as an outflow in the month it must be filed. Stay consistent: if you enter amounts with VAT, outflows must also include it.
5What's the difference with the cash flow simulator?
This calculator solves a period you declare — one month or several. The advanced simulator projects 12 months across three scenarios (base, conservative, aggressive), models churn, seasonality, and delivers comparable KPIs like runway. Use the calculator to verify next month; use the simulator to prepare a mid-term scenario or present it to a committee.
How many months of runway do I have, and what should I do today?
Project your cash month by month using your real revenue, expenses and collection terms — and find out when it runs out.
Results
Month 1: balance crosses your reserve
Minimum balance in the period is -MXN 25,000 (month 1). Act before operations hit critical territory.
Monthly net flow
MXN 15,000
Runway (months without revenue)
0.3 months
Ending cumulative balance
MXN 140,000
Lowest projected balance
-MXN 25,000
Accounts receivable
MXN 50,000
Act now
How many months of runway do I have, and what should I do today?
Months of cash (runway)0.3 monthsMin balance-$25,000
Diagnosis
Your projection turns cash-negative in month 1. At the current burn, the runway doesn't reach the end of the modeled horizon.
Threshold
Operators below 3 months runway are in critical territory. Between 3 and 6 months is caution. Above 6 is the calm operating zone.
Action
This week: review every fixed cost ($20,000/month). Renegotiate rent, cancel unused subscriptions, freeze hiring. Every dollar cut today buys days of runway.
Risk if you do nothing
Without action this week, you enter the insolvency loop: late payments, default interest, vendor loss, team morale collapse. Recovery takes quarters, not weeks.
Runway = cash on hand / total monthly burn (fixed + projected variable at current rate). Minimum balance = lowest point in the month-by-month simulated balance including collection lag. The projection compounds optional revenue growth and discounts delayed receivables per `collection_days`.