The Department of Mineral Resources and Energy (DMRE) announces a fuel-price adjustment on the first Wednesday of every month. The headline is always a cents-per-litre number. The number that matters to your household budget is what it costs you over a month at your actual driving pattern. Those two numbers are connected by some simple arithmetic that almost nobody bothers to do.
Here is the arithmetic.
The 50-cents rule, in one line
For every 50 cents per litre the petrol price moves, a driver doing 15 000 kilometres a year in a standard sedan that uses 8 litres per 100 km pays about R75 a month more (or less) at the pump.
The math: 15 000 km ÷ 100 × 8 L = 1 200 litres per year. × R0.50 = R600 per year. ÷ 12 = R50 per month. Round up to R75 to account for the fact that the average car in South Africa runs closer to 9 L/100 km than 8.
That is the baseline. The next four sections size the same calculation up or down for the four most common driver profiles.
The hatchback driver: short urban commute
A typical small hatchback in the major metros runs at 6.5 to 7.5 litres per 100 km in city driving, and most owners are doing somewhere between 10 000 and 13 000 kilometres a year.
At 11 000 km/year and 7 L/100 km, every 50 cents at the pump = R32 a month.
That sounds small until you remember that the DMRE moved the petrol price by R3.27 a litre in a single adjustment on 7 May 2026. A 150 cent move on a single Wednesday is R96 a month for this driver, every month, until the price moves the other way.
The sedan or compact SUV driver: standard family vehicle
A typical petrol sedan or compact SUV runs at 8.5 to 9.5 L/100 km in mixed driving, and most owners are doing 15 000 to 18 000 km a year.
At 16 000 km/year and 9 L/100 km, every 50 cents at the pump = R60 a month.
This is the profile of most South African households with a single primary car, in line with the household transport-expenditure category in Stats SA’s Income and Expenditure of Households release. Your real cost moves are typically two to three cents-per-litre adjustments a year of meaningful size (50 cents or more), which add up to R200 to R400 a year, every year, without you really noticing it as a budget line.
The bakkie driver: long-distance or work vehicle
A petrol bakkie (Hilux, Ranger, single- or double-cab) typically runs at 10 to 12 L/100 km, and the duty cycle for work or rural use sits closer to 25 000 km a year than 15 000.
At 25 000 km/year and 11 L/100 km, every 50 cents at the pump = R115 a month.
Diesel bakkies follow a slightly different math (diesel pricing moves separately from petrol on the DMRE monthly schedule, though usually in the same direction), but the consumption and distance numbers are similar.
The minibus or shuttle operator: very high mileage
For drivers running 40 000 km a year or more in a 13 to 15 L/100 km vehicle (long-distance taxis, courier shuttles, family minibuses used commercially):
At 45 000 km/year and 14 L/100 km, every 50 cents at the pump = R262 a month.
The high-mileage end of the market feels every cents-per-litre move in real time. It is also why the National Taxi Alliance pays close attention to the DMRE announcement every month and why fare adjustments tend to follow material petrol-price moves with a lag of two to four weeks.
Inland versus coastal: the bit nobody explains
The petrol price you pay in Johannesburg is higher than the price you pay in Cape Town. As of May 2026 the gap between inland 95 unleaded (R26.63) and coastal 95 unleaded (R25.76) is 87 cents per litre, and it exists because the inland price includes the cost of transporting refined product (or refined-product imports) up from the coast.
For the sedan driver above, the inland-coastal gap is the equivalent of about R1 044 a year on 1 200 litres of annual consumption. That is not a saving you can capture (you cannot drive to Cape Town to refuel), but it does explain why filling up in Gqeberha during a coastal holiday genuinely costs less than the same litres at home.
What actually drives the monthly DMRE adjustment
Two factors do most of the work:
- The dollar price of Brent crude on international markets, averaged across the previous month.
- The rand-dollar exchange rate, also averaged across the previous month.
The Central Energy Fund publishes a “snapshot” of the under- or over-recovery building up between adjustments, and by the last week of each month a reasonable estimate of the next Wednesday’s move is already public knowledge. The AA SA publishes a monthly commentary on the same numbers, usually pointing to the same direction of move within 5 to 10 cents of accuracy.
If you want a single number to watch, watch the rand-dollar rate. A 10-cent move on the dollar moves the local petrol price by roughly 6 to 10 cents per litre, holding crude constant. The Central Energy Fund’s most recent breakdown showed a 64-cent weakening in the rand adding about 56 cents per litre to the petrol BFP in a single pricing period.
What is worth doing about it
There is no consumer hack that undoes a structural rand weakening or a global crude spike. There are, however, three things any driver can do this month:
- Know your number. Pick the driver profile above that matches your actual mileage and consumption. The 50-cent-equals-R-X-per-month rule for your car is a single calculation, and once you know it, every DMRE announcement immediately tells you what to plan for.
- Check your tyres. Underinflated tyres add 3 to 5 per cent to your fuel consumption. At sedan-driver levels, that is the equivalent of a 30 to 50 cents-per-litre permanent surcharge. Free at any forecourt.
- Reconsider the morning idle. Most modern petrol engines warm up in motion, not in a stationary idle. Three minutes of pre-drive idling, five days a week across a working year, is the better part of a thirteen-hour stretch of fuel being burned to move nothing.
You cannot move the dollar. You can move the rest.