Law firm lock-up calculator
Lock-up is the delay between doing the work and banking the fee — a median of 134 days in UK firms, per the Law Society's Financial Benchmarking Survey 2026. Enter your own numbers to see how much earned cash is sitting inside that cycle, and what shortening it would release.
The calculator needs JavaScript. The arithmetic it runs: annual fee income ÷ 365 × lock-up days = cash locked up. A firm billing £1.5m at the 134-day median is carrying roughly £550,000 of earned, unpaid work at any time.
What the result means
The first figure is money the firm has already earned — work delivered, much of it already paid for in salaries — that has not yet arrived. The second is what moving to your target releases. It is not new revenue and requires no new clients: it is existing income arriving sooner, once billing runs on a cadence and receivables have an owner.
The days hide in two places, and they need different fixes. Work sitting unbilled (WIP) is a billing-culture problem; invoices sitting unpaid (debtors) is a collections-ownership problem. The mechanics of both are set out in law firm cash flow: WIP, billing and the payment cycle, and the fix step by step in the lock-up guide.
What a good position looks like
Well-run UK firms target 90–110 days; strong performers reach 60–80 in some practice areas. The right target varies by work type — conveyancing and fixed-fee practices can run far shorter cycles than complex litigation. More useful than any single target: a named owner for the position, a weekly review, and a number that moves in the right direction. All five operating benchmarks sit together on the UK law firm financial benchmarks page. US firms: the free law firm profitability calculator sizes utilization, realization, collections and overhead against Clio 2025 benchmarks.
Frequently asked questions
What are lock-up days in a law firm?
Lock-up days measure the total time between doing billable work and receiving payment, combining WIP days (work done but not yet billed) and debtor days (billed but not yet paid). The UK median is 134 days excluding unbilled disbursements, or 144 including them — over four months of delivered work financed by the firm.
How is the cash figure calculated?
Annual fee income divided by 365 gives daily fee income; multiplied by lock-up days it gives the earned revenue outstanding at any moment. A firm billing £1.5m carries roughly £4,100 per lock-up day — about £550,000 at the 134-day median.
How do firms actually shorten lock-up?
Five moves, none requiring new software: same-day time recording, a weekly billing cadence triggered by matter age, one named owner for receivables, a written 30/60/90-day escalation ladder, and measuring fee earners on collected cash rather than billings. Firms addressing only WIP or only debtors typically improve and then stall — both need managing at once.
The numbers are the easy part
Releasing them is an operating-structure job: billing governance, named ownership, a weekly rhythm. The Operational Clarity Call is a focused 30-minute assessment of where your firm's cycle actually leaks and what to fix first.
Book an Operational Clarity Call