Legal Malpractice Damages Calculator
Estimates damages in a legal malpractice claim by measuring the gap between what your case should have been worth and what you actually recovered, plus added costs. Use it when assessing whether an attorney's negligence caused you a quantifiable financial loss.
About this calculator
Legal malpractice damages are measured under the 'case within a case' doctrine: you must prove both that your attorney was negligent and that you would have won (or settled for more) absent that negligence. The formula here is: Damages = (originalCaseValue − actualRecovery) + additionalCosts. The originalCaseValue represents the outcome a competent attorney should have achieved — the expected verdict or settlement. The actualRecovery is what you actually received (possibly zero if the case was dismissed). AdditionalCosts captures extra legal fees, court costs, or expenses you incurred because of the malpractice. This measure aims to put the plaintiff in the position they would have occupied had the attorney performed competently.
How to use
Suppose a reasonable settlement for your personal injury case was $120,000, but your attorney missed the statute of limitations and you recovered nothing. You also spent $8,500 in additional legal fees pursuing the malpractice claim. Step 1 — calculate the recovery gap: $120,000 − $0 = $120,000. Step 2 — add additional costs: $120,000 + $8,500 = $128,500. Your estimated malpractice damages are $128,500. Note that you must still prove the underlying case would have succeeded — courts require you to win the 'case within a case' before this damage figure is awarded.
Frequently asked questions
How do you prove damages in a legal malpractice lawsuit?
To recover damages, you must establish three things: the attorney owed you a duty of care, they breached that duty through negligence or error, and that breach directly caused your financial loss. Causation is the hardest element — you must re-litigate your original dispute as a 'case within a case' to show you would have prevailed but for the attorney's mistake. Expert testimony from another attorney is almost always required to establish the standard of care. Courts will then quantify damages as the difference between the outcome you should have received and what you actually got.
What is the statute of limitations for filing a legal malpractice claim?
Statutes of limitations for legal malpractice vary by state but typically range from one to four years. The clock generally starts running when you discovered — or reasonably should have discovered — the malpractice, not necessarily when it occurred (the 'discovery rule'). Some states use a 'continuous representation' rule that tolls the limitations period while the attorney is still representing you on the same matter. Missing the filing deadline is an absolute bar to recovery, so consulting a malpractice attorney promptly after discovering potential negligence is critical.
What types of attorney errors commonly give rise to legal malpractice claims?
The most common grounds for legal malpractice are missing filing deadlines (particularly statutes of limitations), inadequate investigation or failure to gather key evidence, failure to advise a client of a settlement offer, conflicts of interest, and errors in drafting contracts or legal documents. Transactional malpractice — such as flawed business agreements or estate planning mistakes — is increasingly litigated alongside litigation malpractice. Not every error rises to malpractice; the attorney's conduct must fall below the standard of care exercised by a reasonably competent attorney in the same jurisdiction and practice area.