Methodology
How the quantum calculators work
The quantum calculators value legal money claims from published primary-source rules. This page explains the method they all share. The deadline calculators have their own methodology page.
Deterministic, not generative
Every figure is computed by fixed rule logic encoded from the published source. The same inputs always produce the same output. Nothing is estimated, predicted, or generated.
Versioned, date-effective rules
Every rate, table row, and threshold is stored as a dated record with the date it came into force and the date it ceased to apply. The calculator selects the record in force on the legally relevant date, such as the accident date, so historic calculations use historic rates.
Full working on every figure
A result is never a bare number. Each calculation shows the inputs used, each intermediate step, the exact rule and table row applied, the in-force date of that rule, and a link to the primary source, so the figure can be checked without trusting the tool.
Verify at source
These calculators do not provide legal advice. Every output carries the citation and a link to the primary source on legislation.gov.uk or the relevant official publisher, and figures must be verified there before being relied on.
Module notes
Whiplash tariff
The whiplash calculator encodes the tariff tables from the Whiplash Injury Regulations 2021 (SI 2021/642) and the Whiplash Injury (Amendment) Regulations 2025 (SI 2025/615). The accident date selects the table, with accidents on or after 31 May 2025 taking the uprated table. The prognosis in whole months selects the band, which is inclusive at its upper bound, and the presence of minor psychological injuries selects the column. A judicial uplift of up to 20 per cent under the Civil Liability Act 2018 section 5 can be applied and is capped at the statutory maximum. Claims outside the tariff are flagged, never approximated.
Interest on damages
The interest calculator applies the Special Account Rate to special damages, at the full rate for completed one-off losses and half the rate for continuing losses, and the conventional 2 per cent to general damages from service of the claim form. Interest accrues daily on a 1/365 basis, and the working shows one segment for each rate period, so a window spanning the 9 January 2026 change from 4 per cent to 3.75 per cent shows both segments. The rate history before 3 March 2025 has not yet been loaded, and windows starting earlier are refused rather than approximated.
Fatal accidents
The fatal accidents calculator returns the statutory bereavement award keyed to the date the cause of action accrued, with 15,120 pounds applying on or after 1 May 2020 under SI 2020/316 and 12,980 pounds before. Dependency uses the conventional ratios from Harris v Empress Motors, 75 per cent of joint net income less the survivor income where there are dependent children and two thirds otherwise, and the future multiplier runs from the trial date per Knauer v Ministry of Justice. The Ogden multiplier is entered by the user until the Ogden data module is loaded.
Part 36 consequences
The Part 36 calculator computes the CPR 36.17(4)(d) additional amount, 10 per cent of the first 500,000 pounds of damages plus 5 per cent of the excess, capped at 75,000 pounds, and applies the percentages to costs for non-money claims. Enhanced interest is computed at a rate the user sets above the Bank of England base rate, capped at 10 percentage points. Small claims track cases and relevant periods under 21 days are flagged, not computed.
General damages uplifts
The uplift calculator applies the Simmons v Castle 10 per cent only to figures that do not already include it, which excludes Judicial College Guidelines 17th edition figures, and withholds it where the section 44(6) LASPO exception applies. The inflation top-up applies the ratio of the award month RPI index to the August 2023 base, with the index values entered by the user until the ONS series is loaded. No Judicial College Guidelines bracket figures are encoded anywhere, because that content is proprietary. Bracket figures are entered by the user from a licensed copy.
Ogden method
The Ogden calculator implements the separate valuation method from the Ogden Tables 8th edition. The baseline multiplier and the Table A to D reduction factors are read by the user from the published tables and entered as inputs, because the table data itself has not been ingested and is never fabricated. The discount rate column is selected by the calculation date, with the plus 0.5 per cent rate applying from 11 January 2025. Lifetime care multipliers take no reduction factor, and the disability classification applies all three limbs of the Disability Discrimination Act 1995 definition.
Pension loss
The pension loss calculator capitalises a defined benefit shortfall from retirement using the Ogden pension table for the retirement age and sex, and values defined contribution loss as a stream of lost contributions on the earnings tables instead. The Parry v Cleaver and Longden offset rules are applied to ill-health pension receipts. Complex public sector schemes return the conventional figure with a flag recommending an actuary.
Care and case management
The care calculator aggregates commercial care period by period from hours, rate, and weeks. Gratuitous care applies the conventional 25 per cent discount off the commercial value, adjustable between 0 and 33 per cent with a recorded justification, and no recovery is allowed where the carer is the tortfeasor per Hunt v Severs. Future care multiplies the annual figure by a lifetime multiplier entered by the user until the Ogden data module is loaded.
Periodical payments indexation
The indexation calculator uprates a periodical payment each year by the ratio of the index value for the year to the base year value, under the Damages Act 1996 section 2(8) RPI default or a section 2(9) modified index such as ASHE 6115 per Thompstone. Index values are entered by the user until the ONS series are loaded, and revised values recompute the affected years with the revision shown in the working.
CRU benefit offset
The CRU calculator applies the like-for-like offset matrix from Schedule 2 to the Social Security (Recovery of Benefits) Act 1997. Earnings benefits offset only lost earnings, care benefits only the cost of care, and mobility benefits only loss of mobility, each capped at the head amount with any excess shown as trapped. General damages are untouched except by 1979 Act lump sums, which offset general damages first. Benefits outside the five year recovery period are excluded.
Interim payments and provisional damages
The interim payment worksheet builds the Eeles stage one cap base from general damages, past losses, interest, and accommodation, excluding heads likely to be met by periodical payments, and applies a reasonable proportion that the user sets because no statutory percentage exists. The provisional damages checker walks the three Willson questions and the CPR Part 41 requirements and returns criteria assessments, never a money figure.
Open the interim payments and provisional damages calculator
US life-care plan present value
The US module discounts life-care plan costs and earnings streams to present value using either a net discount rate or the total offset method, as the forum state requires. Every parameter is part of a per-state configuration supplied with the calculation, there are no national defaults, and a calculation without a complete configuration is refused. Every result carries a warning that state law varies and requires legal review in the forum state.