LegalBillingTools

Retainer Balance Calculator

Size a retainer against expected work and set the replenishment point that keeps a matter from stalling.

Last reviewed

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Free · No sign-up · Runs in your browser

A retainer is a cash-flow instrument for both sides. Sized properly it means work continues without interruption and the firm is not funding the client. Sized badly it either blocks the engagement at the start or stalls the matter in the middle.

This calculator sizes the deposit against expected work, reports the rate it will be consumed at, and sets a replenishment trigger with enough headroom for the request to be made and paid.

Your numbers

Results update as you type. Nothing is sent anywhere.

Result

Retainer amount

$8,960

Request replenishment at

$2,240

Estimated fees
$8,160
Expenses
$800
Monthly burn rate
$2,987
Months until the trigger
2.2
Hours covered
24
Hours per month
8

This tool performs arithmetic on the values you enter. It does not provide legal advice and does not create an attorney-client relationship.

A replenishment trigger set well above zero keeps work from stopping while funds are requested. Twenty-five percent of the original deposit is a common choice.

Client funds handling is regulated. Trust accounting, earned-on-receipt language and refundability all depend on your jurisdiction and your bar rules.

How to use the retainer balance calculator

  1. Enter the hours expected for the phase the retainer covers.
  2. Enter the hourly rate and expenses expected in that period.
  3. Enter the number of months the work is expected to span.
  4. Set the replenishment threshold and read the trigger balance.

What people use this for

  • Setting the deposit figure in an engagement letter.
  • Deciding when to request replenishment on a live matter.
  • Explaining the retainer amount to a client.
  • Planning trust account cash flow across several matters.

Worked examples

Every figure below is produced by running this calculator against the example inputs, so the numbers always match the tool.

A three-month phase

24 hours at $340 with $800 of expenses over three months, replenishing at 25%.

Retainer amount
$8,960
Request replenishment at
$2,240
Monthly burn rate
$2,987

A faster-burning matter

The same hours compressed into one month, with a higher trigger.

Request replenishment at
$3,584
Monthly burn rate
$8,960
Months until the trigger
0.6

Burn rate decides the trigger

A matter consuming $2,500 a month needs a very different replenishment trigger from one consuming $8,000. Setting the same percentage threshold across every matter ignores that, and produces requests that arrive too late on the fast ones.

The burn rate in the results is the figure to size the trigger against. The question to answer is how many weeks of work the trigger balance actually buys, and whether that is long enough for a request to be made and paid.

Trust accounting is not a commercial question

Whether funds must be held in a client trust account, whether they can be treated as earned on receipt, when they can be drawn against and what happens to an unearned balance are governed by professional conduct rules.

Those rules differ by jurisdiction, and getting them wrong is a regulatory matter rather than a commercial one. This calculator sizes an amount and says nothing about how it must be held.

Methodology and assumptions

What this calculator does, and what it deliberately does not do.

  • The retainer is estimated hours × rate plus expenses. The burn rate divides that by the months the work spans.
  • The replenishment trigger is the threshold percentage applied to the original retainer.
  • Trust accounting requirements, earned-on-receipt treatment and refundability are jurisdiction specific and are not modelled.
  • The tool performs arithmetic or date counting on the values you enter. It does not interpret a rule, a statute or a contract.
  • Nothing you type is transmitted or stored - the calculation runs entirely inside your browser.

This website provides general informational and productivity tools and does not provide legal advice or create an attorney-client relationship.

The date and deadline tools count days exactly as you instruct them. They do not interpret court rules, statutes of limitation, filing requirements or any other legal authority, and they do not know the rules of your jurisdiction.

Always verify any date, fee, or calculation against the governing rule, the court calendar and your own professional judgement. If you need legal advice, consult a lawyer licensed in your jurisdiction.

Frequently asked questions

What replenishment threshold should I use?

One that buys enough time for a request to be made and paid at the matter’s burn rate. Twenty-five percent is common; a fast-burning matter needs more.

Can I bill against the retainer immediately?

That depends entirely on your jurisdiction and on the engagement letter. Drawing on client funds before they are earned is among the most serious conduct failures.

What happens to an unused balance?

In most jurisdictions unearned funds are returned to the client when the matter concludes. Local conduct rules govern.

Should the retainer cover the whole matter?

Usually not. Sizing it to a defined phase keeps the figure manageable and creates a natural checkpoint for both sides.

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