Converting 650 Supercharging Miles Into Pounds — the Method, Not a Headline
Sam Whitfield, UK EV writer & Tesla owner · published 2026-09-02 · figures checked 2026-07-13.
Every UK referral page gives you a single pound figure for 650 free Supercharging miles. Every one of them has guessed at two inputs it cannot know. Here is the formula instead, with our own assumptions stated, so you can put your own numbers in.
The formula
Value (£) = (miles ÷ miles-per-kWh) × pence-per-kWh ÷ 100
Three inputs, two of which are yours: the reward (650 miles, fixed by the programme), your car's real-world efficiency in miles per kWh, and the tariff you would otherwise have paid at the charger.
Worked, with our assumptions on the table
| Input | Value used | Where it comes from |
|---|---|---|
| Reward | 650 miles | Tesla UK referral programme |
| Efficiency | 3.5 mi/kWh | A mid-range assumption for a Model 3 or Model Y in mixed use — check your own trip screen |
| Energy required | ≈ 186 kWh | 650 ÷ 3.5 |
| Tariff | 41p/kWh | Supercharger member rate, checked 2026-07-13 |
| Value | ≈ £76 | Energy × tariff |
At the non-member rate of 53p/kWh the same reward is worth about £98. That spread — driven by one input — is why a single headline figure is not a fact about the programme.
Why efficiency moves the answer more than people expect
A reward denominated in miles converts into energy at whatever rate your car achieves. At 4.0 mi/kWh, 650 miles needs about 163 kWh; at 3.0 it needs about 217 kWh. Winter motorway driving sits at the thirsty end, and that is the counterintuitive part: a less efficient trip converts the reward into more energy, so the same miles displace more money.
The input that changes the answer most
The tariff you avoid. A reward spent at a motorway Supercharger displaces 53p/kWh; the same reward spent instead of charging at home displaces 24.5p/kWh, and against an off-peak home rate of 7.5p/kWh it displaces very little. Spending free miles on charging you would have done cheaply at home converts a £98 reward into something closer to £14.
That is the single most useful conclusion in this piece: the reward's value is decided by where you spend it, not by the programme.
The deadline that caps the whole calculation
Supercharging distance expires six months from the Grant Date — the day it appears on the account, not the day you ordered. Tesla Credits, which are the referrer's side of the programme, run twelve months. Any value calculation assumes the reward is actually spent inside its window; an unspent allowance is worth zero and cannot be reissued.
What the reward is not
Money off the car. It does not reduce the purchase price, the amount financed, or the transaction value any threshold is measured against. It is also not a US-style FSD trial, and not the mainland European figure of roughly 2,000 km — a distinction covered in the conversion check.
Why we publish the method rather than the number
Two reasons, one principled and one practical. Principled: a single pound figure asserts knowledge of your efficiency and your tariff, neither of which is knowable from here, so it is a guess wearing the clothes of a fact. Practical: a hard-coded figure goes stale the moment Supercharger pricing moves, and it will move. A formula with its inputs on the table survives both problems — you can recompute it in thirty seconds after any price change, without waiting for this page to be updated.
Run it on your own numbers
Open your car's trip screen for efficiency and the Tesla app's stall list for the live per-kWh price, then use the Referral-Savings Calculator. If you are still ordering, the code goes on before you configure:
steven787345
Copy link copies the whole URL (tesla.com/…) — there is no UK checkout field for a bare code. Open it first, then configure & order; the referral shows in your order summary before payment. Referral disclosure.
This post discloses referral links plainly: they are marked rel="nofollow sponsored", and we (or the pooled owner) may earn Tesla credits if you order through one — it costs you nothing extra. Tesla VoltBench is not affiliated with, endorsed by, or sponsored by Tesla, Inc. Full referral disclosure.