Almost every international cargo liability limit is written in "units of account" or "SDR": 2 SDR per kilogram at sea, 8.33 by road, 17 by rail, 26 by air. This guide explains what an SDR is, where the exchange rate comes from, and why the drafters of these conventions chose it.
What the SDR is
The Special Drawing Right is an international reserve asset created by the International Monetary Fund (IMF) in 1969 to supplement its member countries' official reserves. It is not a currency and you cannot pay a supplier in SDR. It is a claim on the freely usable currencies of IMF members, and it serves as the IMF's unit of account. For everyone else, it works as a stable, neutral yardstick of value.
The basket
The SDR's value is based on a basket of five currencies: the US dollar, the euro, the Chinese renminbi, the Japanese yen and the British pound. The renminbi was added on 1 October 2016. The IMF reviews the basket every five years. The most recent review was concluded in May 2022, with the new weights in effect from 1 August 2022:
| Currency | Weight (2022 review) | Fixed amount in the basket |
|---|---|---|
| US dollar | 43.38% | 0.57813 |
| Euro | 29.31% | 0.37379 |
| Chinese renminbi | 12.28% | 1.0993 |
| Japanese yen | 7.59% | 13.452 |
| Pound sterling | 7.44% | 0.080870 |
The weights determine the fixed currency amounts on the changeover date; after that the amounts stay fixed and the effective weights drift with exchange rates. The current valuation period runs until 31 July 2027, when the next review's basket takes effect.
How the daily rate is set
Each business day the IMF values the basket in US dollars using market exchange rates observed around noon in London, and publishes the SDR's value in USD and in many other currencies. Our sources page shows the IMF table we read. At the time of writing, 1 SDR is about US$1.36, €1.21 and C$1.92. The calculator refreshes the rate from the IMF daily.
Why liability conventions use the SDR
The early conventions used gold. The Hague Rules (1924) used £100 sterling (understood as gold value), Warsaw (1929) used the Poincaré gold franc of 65.5 milligrams, and the original CMR (1956) used the gold franc "weighing 10/31 of a gramme and being of millesimal fineness 900". After the end of an official gold price in the 1970s, gold units became unworkable: courts could not agree whether to use the market price of gold or the last official price, and limits varied wildly.
So, from the late 1970s, protocols replaced gold units with the SDR:
- Hague-Visby: the 1979 SDR Protocol introduced 666.67 SDR per package or 2 SDR/kg.
- CMR: the 1978 Protocol replaced 25 gold francs with 8.33 SDR/kg.
- Warsaw: Montreal Additional Protocols (1975) introduced SDR-based limits, including 17 SDR/kg for cargo under MAP4.
- Hamburg Rules (1978), CIM (COTIF 1999), Montreal (1999) were drafted in SDR from the outset.
The SDR suits this job because it is neutral (not any one country's currency), it is published daily by an authoritative source, and as a basket it moves less than any single currency.
Which date's rate applies?
This matters because exchange rates move. The conventions answer differently:
- Hague-Visby: conversion "on a date to be determined by the law of the Court seized of the case" (Art. IV r.5(d)).
- CMR: "on the date of the judgment or the date agreed upon by the Parties" (Art. 23(7), as added by the 1978 Protocol).
- Montreal: conversion in the case of judicial proceedings "according to the value of such currencies in terms of the Special Drawing Right at the date of the judgement" (Art. 23(1)).
So the figure our calculator shows uses today's rate and is an estimate. The amount actually paid may differ.
A worked conversion
A 200 kg air shipment under Montreal: 200 × 26 = 5,200 SDR. At 1 SDR = US$1.35646, that is about US$7,054. If the SDR rose 5% against the dollar before judgment, the dollar limit would rise by 5% too. Check the current figure.
Not every limit is in SDR
Two regimes you will meet often do not use the SDR at all:
- US COGSA still uses a fixed US$500 per package (or customary freight unit), unchanged since 1936. Because it is fixed in dollars, inflation has steadily eroded it, and there is no per-kilogram alternative. See our COGSA example.
- The Carmack Amendment for US trucking starts from actual loss, and released rates are usually expressed in US dollars per pound.
The unamended Hague Rules (£100 per package, gold value) are also still in force in some countries, and courts have reached different answers on how to convert them. Our calculator flags those cases rather than guessing. conversion varies by country
How CarrierLimits converts
We read the IMF's published table of "currency units per SDR" each day and multiply the SDR limit by that rate for US dollars, Canadian dollars and euros. If the IMF cannot be reached, we keep the last stored rates and label them as such. US-dollar limits (COGSA, Carmack released rates) are kept in dollars and converted to other currencies through the SDR cross-rate. Details are on our sources and methodology page.
Countries outside the IMF
Most conventions include an alternative for states that are not IMF members, usually a gold-based "monetary unit" converted under national law (for example CMR Art. 23(8)). These are rarely relevant in practice today.