1. The short answer
Low sulphur heating oil is not one fixed thing: what you actually get depends on which standard your country applies, and the caps range from 10 to 15 parts per million in the strictest cases up to 1,000 mg/kg where no ultra-low mandate exists at all. Germany's DIN 51603-1 caps "Heizöl EL schwefelarm" at 50 mg/kg (VIA-Energy product specification, July 2019). The EU's EN 590 diesel standard, a useful reference point even though it governs road diesel rather than heating oil, allows only 10 mg/kg since the Euro 5 stage in 2009. Northeastern US states require 15 ppm under their own Ultra Low Sulfur Heating Oil rules.
For you as a buyer, the practical point is simple: the number on your delivery note or contract, not the word "low sulphur" by itself, tells you which of these grades you are actually paying for. Modern low-sulphur fuel also ages differently in storage than older, higher-sulphur oil, a point our heating oil shelf life entry covers in more detail.
2. Who sets the limit, and why it differs by country
Sulphur limits for heating fuel are not set by any single global body: they come from national or regional standards bodies and legislatures, which is exactly why the numbers differ so much between Germany, the EU's diesel rules and individual US states. In Germany, DIN, the national standards institute, defines "Heizöl EL schwefelarm" in DIN 51603-1, alongside other specification limits such as a minimum calorific value of 42.6 MJ/kg and a maximum density of 860 kg/m³ at 15°C (VIA-Energy product specification, July 2019).
EN 590 is a European standard for road diesel, not heating oil, but its sulphur history shows how fast a limit can tighten once a body decides to act: from 0.200% under Euro 1 in 1993, down through 0.050% (1996), 0.035% (2001) and 0.005% (2006), to 0.001%, or 10 mg/kg, under Euro 5 in 2009 (Crown Oil EN 590 page; Wikipedia EN 590, accessed 18 September 2026). In the United States, sulphur limits for heating oil are set state by state rather than federally: New York required 15 ppm from July 2012, while New Jersey phased its rule in two steps, 500 ppm from July 2015 and full ULSD-level sulphur from July 2016, with Massachusetts, Maine, Vermont and Pennsylvania running their own separate timelines (EIA, 18 April 2012). Cold-weather grading works the same way, set independently by standard: our winter diesel and CFPP entry covers that separate specification.
3. The limits side by side, with standard and source
The table below lists every sulphur limit found in this research with its governing standard, the date the figure was recorded, and its source. Where two figures for the same standard exist, both are shown rather than averaged.
| Standard / country | Sulphur limit | As of | Source |
|---|---|---|---|
| Germany, DIN 51603-1 ("Heizöl EL schwefelarm") | max. 50 mg/kg (0.005% m/m) | product spec, July 2019 | VIA-Energy |
| EU, EN 590 diesel, Euro 5 stage | max. 10 mg/kg (0.001%) | in force since 2009 | Crown Oil; Wikipedia EN 590 |
| US Northeast, ULSHO (New York) | max. 15 ppm | in force since July 2012 | EIA, 18 April 2012 |
| US, New Jersey ULSHO, Phase I | max. 500 ppm | from July 2015 | EIA, 18 April 2012 |
| US, New Jersey ULSHO, Phase II | ULSD-level sulphur (about 15 ppm) | from July 2016 | EIA, 18 April 2012 |
| UK heating oil, BS 2869 Class C2 kerosene | max. 0.1% m/m (1,000 mg/kg), typical about 0.020% (200 mg/kg) | accessed 18 September 2026 | Crown Oil |
| France, fioul domestique | no verified current ppm limit found | research as of 18 September 2026 | own research, this page |
| Spain, gasóleo C | no verified current ppm limit found; only a general reference to Real Decreto 61/2006 | research as of 18 September 2026 | own research, this page |
Read that last row carefully: it is stated as a gap in the evidence, not as a zero or an estimate. If you order fioul domestique in France or gasóleo C in Spain, ask your supplier for the exact sulphur figure on your own delivery note rather than assuming a number this page cannot verify.
4. Standard grade versus low sulphur: what actually changes
The practical difference between an older, higher-sulphur heating oil and a modern low-sulphur grade shows up in three places: sediment and deposits in the tank and burner, flue-gas sulphur dioxide readings, and, on some appliances, warranty conditions. UK heating oil under BS 2869 Class C2 illustrates the point: its ceiling sits at 0.1% m/m, 1,000 mg/kg, twenty times DIN 51603-1's German ceiling of 50 mg/kg, and even the typical value of around 0.020%, or 200 mg/kg, is four times that German ceiling (Crown Oil, accessed 18 September 2026). A UK household burning typical C2 kerosene is, by these figures, using a materially higher-sulphur fuel than a German household buying "Heizöl EL schwefelarm," even though both are called heating oil.
Switching between grades can require burner adjustment, and that is strictly a job for a qualified technician working from the appliance manufacturer's own instructions, never something to attempt yourself. Some boiler makers write a specific fuel standard into their warranty conditions; whether that applies to your own appliance is a question only the manufacturer or your service technician can answer, and this research found no single rule that covers every make and model, so none is claimed here. The bio-content of your fuel is a separate variable again, covered on our bioheat and HVO blend entry.
As for why low-sulphur fuel costs more to make in the first place: reaching a lower sulphur ceiling requires an additional refining step, hydrotreating, to strip sulphur out of the distillate, on top of meeting the same calorific value, density, flashpoint and viscosity limits the standard also sets (VIA-Energy product specification, July 2019). That extra processing step is the documented mechanism behind the surcharge; this research found no verified per-litre or per-gallon premium figure to attach to it, and our refining margin entry covers how that kind of processing cost generally reaches a wholesale price.
5. What this means when you compare two offers
When two suppliers quote different prices, the first question is not who is cheaper but which sulphur standard each price actually refers to, since a lower headline price can simply mean a higher-sulphur grade rather than a better deal. Ask both suppliers to name the exact standard, DIN 51603-1, EN 590, a state ULSHO rule, or BS 2869 C2, and to state the sulphur figure on the delivery note itself, not only in marketing language such as "low sulphur." A documented DIN 51603-1 designation on an invoice is a stronger signal than the phrase "premium" alone.
What must legally appear on a delivery note varies by country and this research did not find one universal rule naming sulphur content as a mandatory line item everywhere, so treat asking for it as good practice rather than a guaranteed legal entitlement. Whether it is worth paying more for a lower-sulphur grade also depends on your own appliance and how long the fuel will sit in your tank before it is burned, a question our buy now or wait page for the US Northeast walks through in more detail. Run your own numbers, rather than guessing at the premium, in our calculator.
See what two different fuel grades could mean for your own household budget.
Run the calculator6. Misconceptions: what "low sulphur" does NOT mean
"Low sulphur heating oil" does not mean the same 10 mg/kg ceiling as EN 590 diesel, and a lower sulphur figure says nothing about how much heat the fuel actually delivers. Germany's own DIN 51603-1 ceiling, 50 mg/kg, is five times looser than EN 590's 10 mg/kg, so calling heating oil "diesel quality" on sulphur alone overstates what the heating-oil standard actually requires. Energy content is a separate figure again, set by the fuel's calorific value, not by its sulphur ceiling; confusing the two is one of the most common misreadings of this topic.
Cold-flow performance is a separate question again, governed by CFPP grading rather than sulphur content; see our winter diesel entry for that specification. And a fuel's bio-content, FAME or HVO blended in, changes storage and combustion behaviour independently of its sulphur figure, as covered on our bioheat and HVO blend entry. None of these properties, sulphur, calorific value, cold-flow grade and bio-content, can be inferred from any of the others.