Fuel Tank Range Calculator
How far you can drive on a full tank
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Fuel Tank Range Calculator is built to answer one question: how far you can drive on a full tank? The working sits next to it. Type Tank Size (L), Fuel Efficiency (km/L) and Reserve % into Fuel Tank Range; each keystroke re-runs the math. Fuel Tank Range prints the result and its working. That makes Fuel Tank Range handy for quick estimates anywhere. Nothing typed into Fuel Tank Range leaves your device or the tab. Fuel Tank Range handles fuel tank range calculator distance full tank the same way as free online fuel tank range calculator — one of the Auto & Transport tools on CalcProMaster. No sign-up or email — Fuel Tank Range answers as you type.
What the defaults give
A 45 L tank at 16 km/L gives a range of 648 km.
Full-to-empty would be 720 km; the 10% reserve takes 72 km off so you are not running on fumes.
The formula
Range = tank size × efficiency × (1 − reserve%)
45 × 16 = 720 km; × 0.9 = 648 km.
Worked examples
45 L at 16 km/L, 10% reserve → 648 km
45 L at 16 km/L, no reserve → 720 km
60 L at 12 km/L, 10% reserve → 648 km
40 L at 20 km/L, 15% reserve → 680 km
70 L at 9 km/L, 10% reserve → 567 km
Why a reserve is not optional
The published efficiency is an average, not a guarantee. Motorway speeds, headwinds, air conditioning, a loaded car and cold weather can each take 10–20% off it, and they often happen together. A 10% reserve absorbs one of those; a 15% reserve absorbs two. Petrol also lifts the fuel pump from the bottom of the tank, so the last litres are not always usable in the same way.
What moves real range
- Speed. Aerodynamic drag rises with the square of speed; 120 km/h can cost 20% against 90 km/h.
- Load. Passengers and roof boxes both hurt, and a roof box hurts more than its weight suggests.
- Temperature. Cold starts and denser air reduce efficiency, and winter fuel blends differ.
- Tyres. Under-inflation adds rolling resistance; a 10 psi shortfall is worth a few percent.
- Terrain and traffic. Stop-start driving is far worse than the steady figure the tank is rated on.
Use the reserve-adjusted number for planning a leg between fuel stops, and remember that the figure applies to a route like the one that produced your average, not to a mountain pass.
The usable-fuel line is the one to watch: a 45 litre tank at a 10% reserve leaves 40.5 litres to plan with, which is 648 km at 16 km/L. Real consumption rarely matches the rated figure — motorway speeds, air conditioning and a loaded car each take a share, and together they can cut range by a fifth. Refuelling at a quarter tank rather than at the warning light keeps the reserve for the unexpected detour.
Frequently Asked Questions
How far can I go on a 45-litre tank?
About 648 km at 16 km/L with a 10% reserve, or 720 km if you were willing to run it dry.
Why subtract a reserve?
Because real efficiency varies by 10–20% with speed, load and weather, and running out of fuel is worse than refuelling early.
Does the reserve percentage matter much?
Yes at the margin: going from 10% to 15% costs about 36 km on these defaults, which can be the difference between two service stations.
How accurate is the manufacturer efficiency figure?
It is a test-cycle number. Real-world figures are usually 10–25% lower, more so for hybrids and for mostly urban driving.
Does driving faster reduce range?
Yes, significantly above about 90 km/h. Drag rises with the square of speed, so 120 km/h can cost around 20% against 90.
Does the low fuel light leave me a reserve?
Usually 5–8 litres, which is 60–100 km on these figures. Treat it as an emergency margin, not a planning tool.
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