Estimate your monthly and annual fuel spend, with the surcharge where it applies.
Annual fuel spend
—
Monthly spend
—
Base annual cost
—
Surcharge
—
Turning the pump price into a yearly figure
Most people feel fuel cost one tankful at a time and never see the annual total, which is usually the number that should shape decisions about a commute, a car, or a generator. This calculator closes that gap. You give it the pump price per litre and how many litres you burn in a typical week, and it scales that to a monthly and yearly spend. It is deliberately simple and built for ordinary drivers and small operators, not for fleet accounting, though it works just as well for a household running a generator on petrol or diesel.
The base maths is plain. Price per litre times litres per week times 52 weeks gives the annual cost, and dividing by 12 gives the monthly figure. Because it multiplies your weekly habit out across a full year, small changes show up loudly. Shaving even ten litres a week off your usage moves the annual number by a visible amount, which is the point: it makes the cost of a long daily drive concrete.
The 5 percent surcharge, and why it is a toggle
The reason this tool has a checkbox rather than baking the charge in is that the surcharge is not yet a given at the pump. The 2025 tax reform provides for a surcharge of 5 percent on chargeable fossil-fuel products, which is the rate this calculator applies when you switch it on. The structure is worth understanding because it is designed to spare essentials: clean and renewable energy is outside it, and household kerosene and cooking gas are exempt, so the charge targets road fuels rather than the energy a low-income home cooks with.
The catch is timing. The surcharge commences by order of the responsible Minister, so on any given day it may not actually be live. That is why the calculator leaves it off by default and lets you add it to model the effect once it begins. Do not assume it is already in your pump price, and confirm whether it has commenced, and at what rate, with the Federal Inland Revenue Service before treating it as a current cost.
A 50-litre-a-week driver, with the surcharge modelled
Take a commuter buying petrol at NGN 900 a litre and using 50 litres a week. The base annual spend is NGN 900 times 50 times 52, which is NGN 2,340,000, or NGN 195,000 a month before any surcharge. Switch on the 5 percent surcharge to see its effect once it commences, and it adds NGN 117,000 a year, lifting the annual total to NGN 2,457,000 and the monthly figure to about NGN 204,750. These figures use the rate this calculator applies.
Reading the number, and where it overstates reality
One honest limit: the calculator assumes a steady weekly habit across all 52 weeks. Most people drive less when they travel, work from home, or simply have a quiet month, so the real-world figure usually lands a little under the projection. Use the annual number as a planning ceiling rather than an exact bill. A useful tip is to enter your highest typical week and your lowest, run the tool twice, and treat the truth as somewhere in the band between them.
The base cost here is also pre-tax in the sense that it is whatever you actually pay at the pump, which already bakes in distribution margins and any taxes embedded in the headline price. The surcharge toggle sits on top of that. If you are weighing a fuel-hungry commute against rent closer to work, this annual figure is the right number to put on the other side of that scale, and it often tips decisions that feel marginal week to week.
Does the surcharge apply to diesel and cooking gas?
The surcharge is framed around chargeable fossil-fuel products, with clean energy and specifically household kerosene and cooking gas carved out as exempt. Diesel used as a road or generator fuel is the kind of product the charge is aimed at. Because the exact scope and start date are set by ministerial order, check the current list and commencement with the Federal Inland Revenue Service before assuming a particular fuel is in or out.
How do I compare petrol against a more efficient car?
Run the tool with your current weekly litres, then run it again with the litres a more efficient vehicle would use for the same distance. The difference in the annual figures is your yearly fuel saving, which you can weigh against the cost of switching. It is a quick way to see whether better mileage actually pays back over the years you plan to keep the car.