Quick answer
Range = tank size × fuel economy. A 15 gallon tank at 28 mpg gives 420 miles, or 675.9 km.
Enter the tank size and the fuel economy. The calculator returns how far a full tank should last. Use this distance per tank calculator to check your own figures.
Related tools: Fuel Savings Calculator: Yearly fuel savings from a more efficient vehicle. Fuel Cost Calculator: Trip fuel cost from distance, fuel economy and price. MPG Calculator: Miles per gallon from distance and fuel used.
How to use the Distance per Tank Calculator
- Enter tank size (US gal) (above 0).
- Enter fuel economy (mpg) (above 0).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Tank size | A number, in US gal | > 0 |
| Fuel economy | A number, in mpg | > 0 |
Formula and method
Formula
range = tank size × mpg
IEEE-754 double precision; shown to the decimals indicated.
Real range varies with driving and reserve.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Tank size = 15; Fuel economy = 28.
| Result | Value |
|---|---|
| Range | 420 mi |
| In kilometers | 675.9 |
Example 2
Inputs: Tank size = 26; Fuel economy = 17.5.
| Result | Value |
|---|---|
| Range | 455 mi |
| In kilometers | 732.3 |
Example 3
Inputs: Tank size = 12.4; Fuel economy = 35.
| Result | Value |
|---|---|
| Range | 434 mi |
| In kilometers | 698.5 |
The first line is the headline result (range). Below it the distance per Tank Calculator lists in kilometers, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
A theoretical maximum
The figure assumes the whole tank is usable at your average mpg. In practice the low-fuel warning appears with a gallon or two left, and city driving, towing, cold weather and high speed all cut mpg. A range computed at your real mixed-driving mpg is more useful than the window sticker value.
Planning a trip
For a 600 mile day at 420 miles a tank you need at least one stop. Plan to refuel with about a quarter of a tank left rather than driving to empty, especially where stations are far apart.
How the result changes with tank size
Holding every other input at the first worked example, this table changes only tank size. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Tank size | Range | In kilometers |
|---|---|---|
| 7.5 | 210 mi | 338 |
| 15 | 420 mi | 675.9 |
| 30 | 840 mi | 1,351.8 |
| 60 | 1,680 mi | 2,703.7 |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Tank size: entering "0" shows "Tank size must be greater than 0." beside that field and no result.
- Fuel economy: entering "0" shows "Fuel economy must be greater than 0." beside that field and no result.
Choosing between the Distance per Tank Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Fuel Savings Calculator](/automotive/fuel-savings-calculator/) | miles driven per year, current fuel economy and new fuel economy | Annual savings |
| [Fuel Cost Calculator](/automotive/fuel-cost-calculator/) | distance, fuel economy and fuel price | Trip cost |
| [MPG Calculator](/automotive/mpg-calculator/) | miles driven and gallons used | Fuel economy |
| [Stopping Distance Calculator](/automotive/stopping-distance-calculator/) | speed, speed unit and reaction time | Total stopping distance |
| [Distance to Steps Calculator](/lifestyle/distance-to-steps-calculator/) | distance, distance unit and stride length | Steps |
Background: vehicle sizing and speed
A taller tyre travels farther per revolution, so the speedometer reads low and the effective gear ratio becomes numerically lower; a shorter tyre does the opposite. True speed is roughly the speedometer reading times the new tyre diameter divided by the old one. Verify with GPS over a known distance before changing parts.
Assumptions and limitations
- Leave a reserve
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for tank size and fuel economy to confirm this.
Frequently asked questions
How do I find my real mpg?
Fill the tank, reset the trip meter, drive normally and refill; divide miles by gallons added.
Does the tank size include the reserve?
Usually yes, so leave a safety margin.
What is 420 miles in kilometres?
420 miles is about 675.9 kilometres.
What does the Distance per Tank Calculator calculate?
Range on a full tank from tank size and fuel economy. It returns Range and In kilometers.
What formula does the Distance per Tank Calculator use?
range = tank size × mpg. Real range varies with driving and reserve.
What do I need to enter in the distance per Tank Calculator?
You enter Tank size (US gal) and Fuel economy (mpg).
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Leave a reserve.
What is an example of a distance per Tank result?
With tank size 15 and fuel economy 28, the range is 420 mi.
Related calculators
- Fuel Savings Calculator — Yearly fuel savings from a more efficient vehicle.
- Fuel Cost Calculator — Trip fuel cost from distance, fuel economy and price.
- MPG Calculator — Miles per gallon from distance and fuel used.
- Distance to Steps Calculator — Steps needed to cover a distance at your stride length.
- Steps to Distance Calculator — Distance covered by a number of steps.
- Golf Altitude Adjustment Calculator — Estimate how far a golf shot carries at a different elevation, using the Titleist R&D rule of thumb.
Sources
- OpenStax, Prealgebra 2e (Rice University): fractions, decimals, percents, ratios and rounding
- NIST Special Publication 811, Guide for the Use of the International System of Units (SI), Appendix B conversion factors (international inch 25.4 mm, avoirdupois pound 0.45359237 kg)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.