Free Ontario Personal Injury Damages Calculators
The OPIDC 2026, the Merkurator Mediation Genie and a 2025 Cost Convention calculator, free for Ontario personal injury lawyers, mediators, adjusters and claimants.
Valuing a personal injury claim means getting the math right: annual losses, general damages, prejudgment interest, the statutory deductible, contributory negligence and legal costs. One error can change what a client walks away with. Thomson Rogers partner Darcy R. Merkur built these Excel tools to do that math accurately, and they are now free for everyone.
Injured in an accident? These tools are built for legal professionals. Book a free consultation and our lawyers will run the numbers with you.
Which calculator do you need?
| Calculator | Best for | What it does | Access |
| OPIDC 2026 ("the Merkurator") | Plaintiff personal injury lawyers | Full claim valuation: damages, interest, deductibles, contributory negligence, life expectancy, costs and settlement breakdowns | Free download (short form) |
| Mediation Genie – Plaintiff's Counsel | Plaintiff's counsel and claimants | Breaks down cost-plus and all-inclusive offers, and calculates fees under contingency fee or other retainer agreements | Download (.xlsx) |
| Mediation Genie – for All | Mediators, defence counsel, insurance adjusters, claimants | Breaks down cost-plus and all-inclusive settlement offers and calculates the 2025 Cost Convention | Download (.xlsx) |
The Ontario Personal Injury Damages Calculator 2026 (OPIDC)
The OPIDC is the full claim-valuation program once licensed to Thomson Reuters and used by hundreds of personal injury lawyers across Ontario. It works at every stage of litigation, from intake to mediation to trial. Enter the facts of a claim and it shows what the case means for your client after interest, the deductible and any contributory negligence.
What it calculates
- Annual losses and general damages for pain and suffering
- Prejudgment interest and discount rates
- Statutory deductibles for motor vehicle claims
- Contributory negligence reductions
- Life expectancy using Statistics Canada mortality data
- Partial indemnity costs under the old and 2025 Cost Conventions
- Settlement breakdowns (the Mediation Genie page) and a Direction and Account
New in the 2026 edition
Updated Statistics Canada mortality data (2021–2023), the 2026 discount rate, all 2026 statutory deductibles for motor vehicle lawsuits, and updated prejudgment interest rates.
Why it was built
When Darcy Merkur joined Thomson Rogers in 1998, he saw that personal injury lawyers are brilliant advocates but math errors can hurt their clients. The OPIDC gives lawyers accurate numbers and a clear way to present them, consistent with the Law Society of Ontario's rules on contingency fee agreements.
Watch the OPIDC demo video
Merkurator Mediation Genie: Settlement Offer Calculator
The Mediation Genie takes the offers exchanged at mediation and shows exactly who gets what. It handles cost-plus and all-inclusive offers and calculates partial indemnity costs under both the old and 2025 Cost Conventions. It comes in two free versions.
For All: built for mediators, insurance defence counsel, adjusters and claimants, so every party at the table works from the same numbers. Download (.xlsx)
For Plaintiff's Counsel: adds legal fee calculations under contingency fee and other retainer agreements, so clients can see their net recovery before accepting an offer. Download (.xlsx)
2025 Cost Convention Calculator
Under the 2025 Cost Convention, the defendant contributes 15% of the first $200,000 in damages plus 10% of damages above $200,000 toward the plaintiff's legal costs. HST and assessable disbursements are added on top. The convention also applies to claims in 2026.
What the Cost Convention is and why it changed
When a personal injury claim succeeds in Ontario, the defendant must contribute to the plaintiff's legal costs, known as partial indemnity costs. The personal injury bar uses the Cost Convention to estimate a fair contribution without asking a judge or assessment officer to fix it.
For decades the convention was frozen at 15% of the first $100,000 and 10% above that. The 2025 update raises the 15% tier to $200,000, recognizing the front-end work of getting a claim started and matching the $200,000 Simplified Rules threshold.
Example: old vs. 2025 Cost Convention
| Damages paid | Old convention | 2025 Cost Convention | Difference |
| $150,000 | $20,000 | $22,500 | +$2,500 |
| $200,000 | $25,000 | $30,000 | +$5,000 |
| $500,000 | $55,000 | $60,000 | +$5,000 |
| $1,000,000 | $105,000 | $110,000 | +$5,000 |
Figures exclude HST and disbursements. On any claim over $200,000, the 2025 convention adds $5,000 to the cost contribution. The OPIDC and both Mediation Genie versions calculate the old and new conventions automatically.
Frequently asked questions
Are these calculators free?
Yes. The OPIDC 2026 and both versions of the Mediation Genie are free. The Mediation Genie downloads instantly, and the OPIDC requires a short form.
What is the OPIDC, or "Merkurator"?
An Excel-based program for valuing Ontario personal injury claims. “Merkurator” is its nickname, after its creator Darcy Merkur.
How is a personal injury settlement calculated in Ontario?
It starts with damages for pain and suffering and financial losses. Prejudgment interest, the statutory deductible (in motor vehicle claims) and any contributory negligence reduction are applied, then partial indemnity costs, HST and disbursements are added. The OPIDC runs each step for you.
Is there a 2026 Cost Convention?
No. The 2025 Cost Convention applies to claims in 2026.
What's the difference between a cost-plus and an all-inclusive offer?
A cost-plus offer pays damages with costs and disbursements on top. An all-inclusive offer is one figure covering all three. The Mediation Genie breaks down both so you can compare them.
Can I use these if I'm not a lawyer?
Yes. The Mediation Genie for All is designed for mediators, adjusters and claimants. If you’ve been injured, book a free consultation so a lawyer can make sure every loss is counted.