The formula is extremely simple. The implications are not. Here's the full breakdown of what happens when you hit Calculate.
BangMiles has one job: take a set of numbers, multiply them together in the right order, and convert the result into a unit that makes you feel something. Here's exactly how it does that.
Everything BangMiles produces comes from a single calculation:
That's it. Four numbers multiplied together. The result is in inches, which then gets converted into feet, or miles, depending on which unit makes the number land hardest.
The conversion chain:
BangMiles displays whichever unit makes the most sense for the size of the result. Under a foot: inches. Under a mile: feet. One mile or more: miles. This is called "best unit" logic and it's the closest thing to editorial judgment this calculator has.
If you enter your length in centimetres, BangMiles converts it to inches before calculating, using the internationally agreed conversion of 1 inch = 2.54 cm. The final result is still expressed in imperial units because miles are more dramatic than kilometres and this is not a calculator for the faint of heart.
BangMiles has two main calculation modes. In Per Month mode, you enter a monthly frequency and get a monthly (and projected annual) mileage. Simple.
In Total Since Date mode, BangMiles works out how many months have elapsed between your start date and today, then multiplies by your monthly average. This is where the month-counting logic comes in, and it's where things get slightly philosophical.
Say your start date is 15 January and today is 10 February. How many months is that?
Inclusive counting gives more generous results. Full months is more conservative. We default to Inclusive because "you were there in January" is a reasonable enough basis for including it.
The Odometer is the third mode: you enter an anniversary date and BangMiles automatically calculates the running total from that date to today, updating every time you visit. It's the cumulative lifetime figure. Some users find this inspiring. Others find it troubling. Both reactions are valid.
The headline figure switches units based on thresholds:
Once you have a mileage, BangMiles compares it against a set of real-world distances — the English Channel, a marathon, the length of the M25, the distance to the Moon (for the truly committed). These are fixed reference points. When your total exceeds one, the chip lights up. It's meaningless and somehow motivating.
BangMiles assumes perfect consistency: same length, same thrust count, same frequency, every month. Real life involves variation, interruption, and the occasional injury. The number you get is a model, not a measurement. Treat it accordingly: share it on social media, submit it to the leaderboard, use it to win arguments. Do not present it to a doctor as evidence of anything.
The full source of BangMiles is straightforward PHP and vanilla JavaScript. The formula has not changed since v1. Only the presentation has evolved. The maths was always this simple.