Route Fit Sandbox

Where does the range actually go?

The calculator answers the whole ride at once. This one takes it a piece at a time, so it can tell you which piece costs you most, and why.

Read the hills off the terrain

Trace your ride. Tap the corners of the route you actually take. The turns, not every meter. We measure the line you drew and read the hills underneath it. Traced this way there is nothing to type and no address to give.

Where you are riding type both ends, or tap the corners on the map

Typing an address is the one thing on this page that leaves your browser. It goes straight to Stadia Maps, the company that draws this map, so they can turn it into a coordinate and work out the road between two of them. It never touches our servers, and nothing is sent until you press the button.

From To

Drag to move. Tap to drop a point.

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Who else sees anything, and what they say about it

Almost nothing you type leaves this page. Your weight, your speed, the stretches you enter — read on this device, used on this device, not sent. The one exception is the address box, which sends the two places you type to our mapping provider when you press the button beside it, and says so where it sits. There is no server of ours in the path, so there is nothing on our side to keep.

Drawing a map is different, and we would rather tell you than have you find it. To show a map, your browser asks Stadia Maps for the numbered squares covering the area on screen. To read the hills, it asks Amazon’s public terrain store how high the ground is there. Those numbers are worked out from where you traced. They are not your address. They are not nothing either.

We chose Stadia on purpose. These are their words, not ours:

“API request and access logs: approximately 7–14 days”, Stadia Maps Data Processing Addendum, Annex I
“end users of applications built with our services never receive cookies from Stadia Maps”, Stadia Maps Privacy Policy, 22 July 2026
“We do not sell, rent, or trade your personal information”, same

We quote them because we cannot vouch for them. We can tell you what this page does; only they can tell you what they do, and you are entitled to read it yourself, in their privacy policy.

We asked, and here is the answer, including the half we would rather not be reporting. Their agreement permits use of data for “service improvement, analytics and benchmarking,” so we asked Stadia directly whether that reaches the contents of a request — the coordinates — or only figures about the service. They replied on 11 August 2026 that it “may” reach the contents, and that when it does the data must first be anonymised to a standard their contract ties to GDPR Recital 26, that pseudonymised data expressly does not count as anonymous, and that they undertake not to attempt to re-identify it. The request that carries those coordinates sits, on their own reading, in the API request logs their Annex I says are kept for “approximately 7–14 days.” That is a real fence and it is still a promise rather than a prohibition — we cannot audit them, and we are not going to imply we can. Read the clauses yourself instead of taking ours: Annex I — what is transferred · §3.3 — anonymous data.

What we chose not to build: no server of ours between you and them, so we never receive the coordinates, and no API key on this page for anyone to take. What we did build, and you should know it: an address box that turns a place name into a location. It is the one control here that sends anything, it sends only when you press the button beside it, and it says so where it sits. A route you trace, paste or drop in is never sent anywhere at all; those hills are read from squares your own browser already fetched.

Everyone your browser has actually talked to is listed on this page, counted live, see “What leaves your browser” above. Press F12 and open the Network tab if you would rather check than take our word.

Reach rings all —

1 · The route by shape, or by name if you type it

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The battery what you are running on, before the route touches it

Expected range — Nothing here yet. It fills in as soon as there is a route to run.

Watt-hours — Nothing here yet. Spent and left over are the same number seen from both ends.

2 · How you would ride it the same route, three ways

3 · The plan where it goes, piece by piece

How to save it

The same route with one thing changed, run back through the same arithmetic.

The other two doors into the same route

One latitude, longitude per line. Or paste a map link straight from your phone and we will read the numbers out of it. Nothing is looked up and nothing is sent; the numbers are already in what you pasted.

Or drop in a GPX / GeoJSON

The map and the hills need no address from you, so a route you trace, paste or drop in looks nothing up. What does go out: your browser asks OpenStreetMap for the map squares you are looking at, and Amazon’s public terrain service for the squares your line crosses. No account, no key, and nothing about you attached. But which squares get asked for is worked out from where you are looking and where you rode, and we are not going to pretend otherwise. Press F12 and watch it happen. The line you draw, the distances and every number below it are worked out in this page and go nowhere.

What this tool uses, and what it does with each thing.

All of it is worked out in this page, on your device, as you change it. Nothing here is stored, and there is nothing to sign into. Here is every number it asks you for and the job that number does:

Your pack, as volts × amp-hours, plus whether it is new or has some age on it. This sets the size of the tank. Nothing else on the page can be worked out without it.
How far you are going, either typed or traced on the map, and whether you come home on the same charge. A distance means two different rides depending on that second answer, which is why it is asked beside it.
The hills, either your own answer or the terrain read from underneath a route you trace. Gradient is usually the most expensive thing on a ride and it is the one riders leave out.
You, loaded. Rider plus the bag, the jacket, the shopping. Weight moves the zap rate, so a figure that assumes a light rider flatters every number after it.
Your pace, your stops, the weather and your tire pressure. Speed is the biggest single lever because drag climbs faster than speed does; cold, stop-start traffic and soft tires each take their own bite, and they multiply rather than add.
If you ask for the comparison: what you travel by today and what it costs you, so the tool can tell you whether this is actually better for you. It is built to be able to answer no.

Those numbers produce one number, watt-hours per mile, and everything you see is read off it: the range band, where the range goes, and whether your ride fits with the cautious end of the band rather than the best possible day. Our server is never asked for an answer and never sends one.

Here is everything on this page that talks to the outside, and you should know which:

Page views go to Google Analytics, meaning which page was opened, not what you typed into it.
The address box on the Route Fit tab sends the two places you type to our mapping provider, and only when you press the button beside it. It is described in full where it sits.
The map and the hills, on that same tab and only once you use them: your browser fetches map squares from OpenStreetMap and terrain squares from Amazon's public service. No account and no key, and the panel there names every one of them and counts them live.
There is no email field and no login anywhere on this page, and everything not named above is worked out where you are standing.

You do not have to take our word for any of that. Press F12, open the Network tab, and use the planner. Watch what goes out, and watch that nothing goes out that is not named above.

Built on the same arithmetic as the Spec Decoder and the Fit Quiz. One engine, three doors into it.

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Where does the range actually go?

What this tool uses, and what it does with each thing.