Working Capital Calculator

This is an indicative estimate, not a quote. Actual availability depends on which invoices are eligible, customer concentration limits and each lender's criteria. Construction businesses funding applications for payment will typically see lower advance rates. Invoice Finance Experts arranges facilities, it does not lend money.

What these figures actually mean

The first figure, the amount tied up in unpaid invoices, is your outstanding debtor book: the money you have already earned that is currently sitting in other businesses' bank accounts. It is calculated from your monthly invoicing and how long your customers take to pay. Invoice £100,000 a month with customers paying in 45 days and, at any given moment, roughly £150,000 of your money is out there waiting. The second figure is what invoice finance could release from that book: the outstanding balance multiplied by the advance rate, the percentage of each invoice a funder pays up front. That released cash is not a loan against the future. It is your own revenue, arriving when the work is done instead of when your customers' payment runs decide.

How the calculation works

The sums are deliberately simple. Your outstanding debtor book is your monthly invoiced sales multiplied by your debtor days divided by 30. The cash released is that book multiplied by the advance rate. We default the advance rate to 85% because that is a reasonable market rule of thumb, and the slider runs from 70% to 90% because that is where most facilities genuinely sit. If you are not sure of your debtor days, take the payment terms you give customers and be honest about how much they overshoot. Terms of 30 days that routinely get paid at 50 are 50-day debtor days, and the difference is exactly why the calculator matters. For practical steps to bring that number down, read our guide on how to reduce debtor days.

Why your real figure will differ, and which direction

Treat the result as a well-informed estimate rather than an offer, because a funder will refine it in several ways. Not every invoice qualifies: disputed invoices, very old debt and sales to consumers are excluded, and funders apply concentration limits when one customer dominates a ledger. Sector matters too. Recruitment invoices backed by approved timesheets sit at the top of the advance range, while construction debt, funded through applications for payment with set-off and retentions in play, typically sees advance rates around 50 to 70 per cent, meaningfully below the calculator's default. And the type of facility changes the shape of the answer: a whole ledger facility funds the book continuously, while selective invoice finance funds only the invoices you choose. None of this makes the estimate useless. It makes it a starting point, and a genuinely useful one, because the order of magnitude is usually right.

A number is not a decision

Knowing that £200,000 is trapped in your ledger tells you the size of the prize, not whether invoice finance is the right way to claim it, or which of the types of facility fits, or which provider will offer the best terms for a business like yours. That is the conversation our brokers have every day: what the funding would genuinely cost, what it would change, and whether the honest answer for your business is a whole ledger facility, selective funding, or waiting. Tell us your numbers and we will do the part no calculator can.