More cash in and outOpen invoices, sales change, draw, equipment, loans
Operating: customer payments in; payroll, materials, rent and taxes out. Investing: equipment sold or bought. Financing: loans and owner money in; repayments and draws out.
See month by month
Net cash flow is the cash that comes in minus the cash that goes out over a month, quarter or year, and your ending balance = starting cash + net cash flow. On a cash flow statement it splits three ways: operating (customer payments, payroll, materials, rent), investing (equipment bought or sold) and financing (loans in, repayments out). Bring in $5,000 and pay out $4,000, and net cash flow is +$1,000. The median small business keeps about 27 days of outflows in the bank, so a month of costs in reserve puts you ahead of half of them.
How to calculate cash flow
Net cash flow = cash in minus cash out; ending cash = starting cash + net cash flow. This business cash flow calculator runs both.
| Plan month by month owners forecasting ahead | Cash flow statement one month, quarter or year | |
|---|---|---|
| Cash in | The share of each month's sales paid on the day, plus earlier invoices as they come due, plus any loan, owner money or other income | Operating inflows + investing inflows + financing inflows |
| Cash out | Payroll + materials as a share of sales + rent and overhead + loan payments + taxes + owner's draw + any equipment bought that month | Operating outflows + investing outflows + financing outflows |
| Net cash flow | Cash in minus cash out, worked out for every month | Operating net + investing net + financing net |
| Ending cash | Last month's ending cash + this month's net cash flow | Beginning cash balance + net cash flow |
Worked example: one month for a service shop that starts with $10,000 in the bank
How this cash flow calculator works: the Plan month by month tab starts from your bank balance, collects each month's sales on your payment terms, takes out every cost in the month you pay it and carries the ending cash forward. It flags the lowest balance, the first month below zero and your runway. The statement tab totals operating, investing and financing cash for one period and adds it to your beginning balance. Figures in brackets are cash going out.
When to use this cash flow calculator
Reach for it whenever a decision depends on the bank balance a few months from now, not the profit on last month's books.
- Monthly or quarterly cash planning: project what the business will hold at the end of each month for the next 6 to 24 months.
- Customers who pay late: if you invoice after the job and customers take 30, 60 or 90 days, sales and cash stop lining up. Set the share paid on the day and the payment delay, and this business cash flow calculator shows exactly which months feel the gap.
- Equipment purchases and financing: a new van, a jetter or a mini excavator is a big one off hit. Put it in the month you plan to buy, add the loan as money in and the repayment as a monthly cost, then see whether the balance holds.
- New hires or a bigger lease: add the extra payroll or rent and check the lowest month stays above zero.
- Runway for a new business or freelancer: when more goes out than comes in, your starting cash turns into months of runway. That is the number to watch while a new shop or a solo operator builds up regular customers.
- Comparing financing options: try a loan, a credit line draw or an owner top up and compare the repayment hit.
- Slow season planning: roofing, HVAC and landscaping all have quiet stretches. A negative sales change per month models the dip, so you know how much cash to carry into it.
- Splitting a past period: the statement tab breaks a month, quarter or year into operating, investing and financing.
What counts as operating, investing and financing cash flow?
Every dollar that moves through the business lands in one of three buckets. Keeping them apart shows whether the daily work pays its own way, or whether a loan is quietly holding the balance up.
| Section | Cash in | Cash out | In a service business |
|---|---|---|---|
| Operating activities | Customer payments, deposits and other receipts from the work itself | Payroll, materials, rent, insurance, fuel, marketing, taxes and interest | A card payment for a finished repair; the supply house bill |
| Investing activities | Selling a used truck, old tools or property | Buying vans, tools, equipment or property | Buying a drain camera or trading in a van |
| Financing activities | New loans, credit line draws and money the owner puts in | Loan principal repaid, owner distributions and dividends | An equipment loan landing, then the monthly payments going out |
Depreciation never leaves the bank, so it is not cash out. The full price of a truck or tool counts in the month you actually pay for it.
How much cash should a small business keep on hand?
The median small business holds 27 days of cash outflows in the bank, and half hold less than a month. Repair and construction businesses run thinner than that.
| Industry | Median cash buffer | Industry | Median cash buffer |
|---|---|---|---|
| Restaurants | 16 days | Metal and machinery manufacturing | 28 days |
| Repair and maintenance | 18 days | Health care services | 30 days |
| Retail | 19 days | High tech manufacturing | 32 days |
| Construction | 20 days | Other professional services | 33 days |
| Personal services | 21 days | High tech services | 33 days |
| Wholesalers | 23 days | Real estate | 47 days |
How do late invoices affect small business cash flow?
More than half of US small businesses (56%) are owed money on unpaid invoices, and the average amount outstanding is $17,500 per business.
| What US small businesses report | Figure |
|---|---|
| Owed money on unpaid invoices | 56% |
| Average unpaid amount per business | $17,500 |
| Some invoices more than 30 days overdue | 47% |
| Share of invoices more than 30 days overdue | Nearly 1 in 10 |
| Cash flow problems, many late invoices | 50% |
| Cash flow problems, few late invoices | 34% |
From a January 2025 survey of 2,487 US small businesses with up to 100 employees.
Here is what payment timing does in the business cash flow calculator above. Take the starting figures in the Plan month by month tab: $40,000 billed a month, 60% paid on the day, $3,500 of net cash flow a month. If the other 40% arrives after 30 days, the year ends at $62,000. Stretch it to 60 days and the balance drops to $11,000 in month 2 and finishes at $46,000. At 90 days the same business goes $1,500 below zero in month 3, with no change to sales or costs.
What changes your cash flow from month to month?
Sales are only half the story. These are the things that push the balance up or down even when the work stays steady.
| Factor | What changes the cash | Effect on the balance |
|---|---|---|
| Payment terms | Work on 30 or 60 day terms pays later while payroll goes out now, and nearly 1 in 10 invoices runs over 30 days late. | Cash arrives one to three months after the job |
| Seasonality | Busy months fill the account and quiet ones drain it, since rent and core staff cost the same. | Swings in cash in, steady cash out |
| Payroll timing | Paying every two weeks gives 26 paydays a year, so most years two months carry three payrolls. | Higher cash out in those two months |
| Materials and draws | Parts bought ahead of the job, and what you pay yourself. | Cash out before the customer pays |
| Equipment | A van or machine paid in cash lands all at once. | One big drop in a single month |
| Loans and credit lines | Borrowed money lifts the balance now; repayments pull it down later. | Up now, down every month after |
| Estimated taxes | Federal estimated tax is due April 15, June 15, September 15 and January 15. | Four lump payments a year |
| Depreciation | A bookkeeping expense that never touches the bank. | No effect on cash |
How do service businesses build a cash flow forecast?
A forecast that works is short, honest about when money actually moves, and updated every month. Six steps get you there:
- Start from the bank balanceUse the real number in your business accounts today, not the figure on the books.
- List cash in by when it landsSplit each month's work into what customers pay on the day and what they pay later. Add invoices already out, sorted by when you expect them, and leave out anything you are not sure you will collect.
- List costs by when they are paidPayroll on its real paydays, supplier bills on their due dates, rent, insurance, loan payments and the quarterly tax bill. Your own draw goes in too.
- Add the one off itemsEquipment, a new loan, a big deposit.
- Find the low pointThe month with the smallest balance is the one that matters. If it dips below zero, move a purchase, chase invoices sooner, or line up credit before you get there.
- Update it every monthSwap last month's guesses for actual figures and roll one month forward.
The Plan month by month tab in the calculator follows these same steps.
Home service owners: cash flow trouble starts before the invoice.
Late paying customers squeeze the account, and every call that rings out to voicemail is a job that never becomes an invoice at all. ServiceAgent answers every call around the clock, books the work into your calendar and sends the follow up, so more of the jobs you could win turn into cash in the bank.
Book a free demoFrequently asked questions
Plain answers on net cash flow, receivables, runway and how to read this calculator.
Book a free demoHow do you calculate net cash flow?
Add up all the cash that came in during the period, then subtract all the cash that went out. Net cash flow is cash in minus cash out. On a cash flow statement you reach the same number by adding operating, investing and financing cash flow together, and your ending balance is your starting cash plus that net figure.
What is a good cash flow amount?
Any month where more cash comes in than goes out is a good start, but the cushion in the bank matters just as much. The median small business holds about 27 days of cash outflows in reserve, and repair and maintenance businesses hold about 18. A full month of costs in the bank puts you ahead of half of all small businesses.
What is the difference between cash flow and profit?
Profit is what your books say you earned, usually counted when the invoice goes out. Cash flow is the money that actually landed in or left the bank account. A shop can look profitable on paper and still struggle to make payroll when customers pay 60 days late.
Do I include depreciation in cash flow?
No. Depreciation is a non cash expense, so it never leaves your bank account. Leave it out of cash out, and enter the full amount you actually paid for a truck or a piece of equipment in the month you paid it.
How should I handle receivables and payables?
Count cash when it moves, not when the invoice is written. When unpaid customer invoices grow, your cash goes down. When your own unpaid supplier bills grow, your cash goes up for now. The Plan month by month tab handles customer receivables for you through the Paid on the day and Rest paid after fields.
Can this calculator help plan for a loan or a big purchase?
Yes. Enter the loan as new money in and the monthly payment as a loan payment, or put an equipment purchase in the month you plan to buy. Then check whether any month drops below zero and how much runway is left.
Should I include owner's draws or my own salary?
Yes. Whatever you take out of the business is cash leaving the account, so add it as an owner's draw. Leaving it out makes the forecast look healthier than the bank balance will.
How often should I run a cash flow projection?
Monthly at a minimum. Run it weekly when cash is tight, when you are hiring, or when you are growing fast enough that new jobs and invoices outpace what you collect.
Does this cash flow calculator handle seasonality?
Partly. Use the Sales change per month field to model a ramp up or a slowdown, or run the statement tab once per month or quarter with that period's real numbers. For trades with a sharp busy season, like HVAC or landscaping, plan the slow months on their own so the low point is easy to see.
How accurate is this cash flow calculator?
It is only as accurate as the numbers you enter. Use real figures from your bank statements and invoices rather than hoped for sales, and the next few months will land close. The further out you plan, the more the result depends on your assumptions.
Leads growth and product marketing for ServiceAgent at SaaS Labs, where he has worked in product marketing since 2020. Writes ServiceAgent's coverage of AI call answering, CRM and home services operations.
Published by ServiceAgent, the AI front office for home service teams. Estimates only. Results depend entirely on the figures you enter and are not financial, tax or accounting advice. Check big decisions with your accountant.