How the calculation works
Formula
Ci(x) = Gi + x·(q/100)·pi
For tariff i with monthly-equivalent base fee Gi and price pi, the total monthly cost at a monthly charging energy E is Ci(E) = Gi + E*pi. Since monthly energy E = x*q/100 follows from distance x and effective consumption q, equivalently Ci(x) = Gi + x*(q/100)*pi. This is a straight line: Gi is the intercept at x = 0, (q/100)*pi is the slope.
Why are the tariff curves straight lines?
The fixed base fee determines the y-intercept: at 0 km, cost equals exactly the base fee. The kWh price determines the slope: every additional kilometer needs roughly q/100 kWh and therefore adds (q/100)*price in cost. A tariff with a high base fee and low kWh price starts expensive but rises slowly; a tariff with no base fee and a high kWh price starts at zero but rises quickly. This is exactly why tariff lines with different base fees and different prices cross at exactly one point -- the break-even.
When does a charging subscription pay off?
When does a charging subscription pay off? Exactly at the point where the savings from the lower kWh price offset the extra base fee: E_break = (G2 - G1) / (p1 - p2). With the effective consumption q (kWh/100 km), this converts to a mileage of km_break = 100 * E_break / q. Example: Tariff A costs €0/month and €0.59/kWh, Tariff B costs €5.99/month and €0.49/kWh. Difference: €5.99 base fee against €0.10/kWh savings. Break-even: 5.99/0.10 = 59.9 kWh/month, or roughly 300 km/month at 20 kWh/100km. Below that volume Tariff A is cheaper, above it Tariff B is cheaper.
Worked example
Effective consumption: 20 kWh/100 km. Monthly distance: 1,000 km. Charging energy: 200 kWh/month. Tariff A: €0/month base fee, €0.59/kWh. Tariff B: €5.99/month, €0.49/kWh. Tariff C: €11.99/month, €0.42/kWh. Costs: Tariff A = 0 + 200*0.59 = €118.00/month. Tariff B = 5.99 + 200*0.49 = €103.99/month. Tariff C = 11.99 + 200*0.42 = €95.99/month. At 1,000 km/month, Tariff C is cheapest. Break-even A vs B: E = 5.99/(0.59-0.49) = 59.9 kWh/month, i.e. x = 59.9/20*100 = 299.5 km/month. A and C also mathematically intersect at E = 11.99/(0.59-0.42) ~ 70.5 kWh -- but there, Tariff B is already cheaper than both (about €40.55 vs about €41.60 for A and C). The A-C crossing is therefore a mathematical line intersection, but NOT a relevant tariff switch -- the actual switch runs from A to B at 59.9 kWh and from B to C only at about 85.7 kWh (~429 km/month).
What if I mostly charge at home?
If you mainly charge at home or at work, don't use your total mileage as the public charging volume. Example: 1,500 km total distance, 20 kWh/100 km, with only about 30% charged publicly -- that gives a relevant public mileage of 450 km and a public energy volume of 90 kWh/month. Only these 90 kWh determine whether a public tariff's base fee pays off, not the full 1,500 km. Enter only the distance whose energy is actually drawn through the tariffs compared here.
Monthly or annual charging subscription?
A monthly base fee can be compared directly. An annual fee is divided by 12 for the monthly comparison: G_month = G_year/12. Example: €59.99/year corresponds to roughly a €5.00/month equivalent. This does NOT mean the provider actually charges €5 every month -- the annual amount is often billed once, upfront. For the yearly cost, this calculator therefore uses the actually entered annual amount once, rather than adding the monthly-equivalent value twelve times. Annual subscriptions can also include minimum terms, different cancellation rules, discounts, or automatic/non-automatic renewal -- these contractual conditions are not evaluated by the cost formula and must be checked in the provider's terms.
kWh vs kilometers
Charging tariffs are billed in EUR/kWh -- the kilowatt-hour is the direct billing quantity. Kilometers, however, are the more intuitive quantity for most users. Converting between them requires the vehicle's effective consumption (kWh/100 km at the charger, ideally including charging losses). This calculator therefore shows break-even points in both kWh/month and km/month, so the result can be related to provider information stated in either quantity.
Own network vs roaming
Many charging tariffs charge different prices depending on the operator's own network, a roaming partner, the country, or the specific station. A comparison is only meaningful if both tariffs are compared for the same charging scenario. Comparing tariff A's own-network price against tariff B's roaming price is misleading unless that genuinely reflects expected usage. If you mainly charge at IONITY, compare the prices each tariff actually charges at IONITY; if you mainly charge at Aral pulse, compare the prices that apply there -- not each provider's headline price.
AC, DC and HPC pricing
Charging tariffs often distinguish between AC (alternating current, slower charging), DC (direct current, fast charging) and HPC (high-power charging, especially fast charging). Some providers use the same price for all three, others do not. This calculator uses ONE entered kWh price per tariff. With a mixed charging profile (e.g. partly AC at home, partly HPC on the road), either calculate separate scenarios or determine a weighted average price by hand. An automatic AC/DC/HPC weighting is deliberately not included in this version, to keep the model understandable.
Ad-hoc charging or a contract?
Ad-hoc charging (paying via app or card without a contract, usually with no base fee but a higher kWh price) can also be entered as a tariff with 'No fee' and compared directly against contract or subscription tariffs.
When does which tariff type pay off?
Occasional public charger: little public charging, a high base fee is hard to amortize -- a no-fee tariff or ad-hoc charging is often more sensible. Regular public charger: medium energy volume, a smaller subscription tariff can already become cheaper. Frequent driver/long-distance: high public energy volume, here the lowest kWh price increasingly matters, even at a higher base fee. This classification does not replace a calculation: the actual break-even always depends on the specific fees and prices entered.
Comparing EnBW, IONITY, Aral pulse & co.
You can, for example, enter EnBW mobility+ L, IONITY Power and Aral pulse Extra as three tariff scenarios. The calculator shows which tariff is calculated to be cheapest for your entered charging volume. It answers the COST question only. It does NOT evaluate network coverage, site quality, reliability, app quality, or charge-point availability. The calculator compares cost -- for the actual tariff choice you should also check whether the charging network fits your typical routes.
Why charging tariff comparison is difficult
Public charging prices are market-based and can differ by provider, network and access model. For ad-hoc charging, prices must be made transparent before the charging process under current regulatory requirements. This calculator, however, does NOT retrieve real-time prices from charging stations -- it only processes the values entered by the user. The currently valid price should always be checked in the provider's app, at the charging station, or on the official tariff page.
What the calculator does not include
- Different AC prices
- Different DC prices
- Different HPC prices
- Roaming surcharges
- Operator- or location-specific prices
- Dynamic or time-dependent prices
- Blocking/idle fees
- Parking fees
- Per-session fees
- Card issuance fees
- Activation/unlock fees
- Promotional first-month prices
- Loyalty or existing-customer discounts
- Manufacturer-specific incentives
- Membership requirements
- Cancellation terms
- Minimum contract durations
Common mistakes when comparing EV charging tariffs
- Comparing only the EUR/kWh price while ignoring the subscription fee.
- Comparing only the monthly fee while ignoring the actual charging volume.
- Using total driven kilometers even though only a fraction is actually charged using the public tariff.
- Using vehicle-side consumption without charging losses.
- Comparing one provider's own-network price with another provider's roaming price without realizing it.
- Ignoring AC/DC/HPC price differences.
- Treating an annual upfront fee as if it were literally billed monthly.
- Using promotional prices as permanent prices.
- Ignoring blocking/parking fees when regularly occupying a station beyond the free period.
- Assuming the tariff with the lowest calculated cost automatically has the best charging network for the user's routes.
Frequently asked questions
When does an EV charging subscription with a monthly fee pay off?
From the break-even point onward, where the savings from the lower kWh price offset the base fee. Below that charging volume the no-fee tariff is cheaper, above it the fee-based tariff is cheaper.
How do I calculate the break-even between two charging tariffs?
E_break = (fee difference) / (kWh price difference). Using the effective consumption, this energy value converts to a distance: x_break = 100*E_break/q.
Should I compare charging tariffs in kWh or kilometers?
kWh is the direct billing quantity used by providers. Kilometers are more intuitive but need the vehicle's effective consumption to convert. This calculator shows both.
Which EV consumption value should I enter?
The effective consumption at the charging point per 100 km, ideally including charging losses. Using only the trip-computer consumption can underestimate actual charging costs. Charging losses can be determined separately with the EV Charging Loss calculator.
Are charging losses included?
Only if they are already included in the entered effective consumption. Ignoring them tends to underestimate actual tariff cost.
Can I compare a no-subscription tariff with a charging subscription?
Yes. Set the fee to 'No fee' / €0. This is one of the calculator's main purposes.
How do annual charging subscriptions compare with monthly subscriptions?
An annual fee is divided by 12 for the monthly comparison (monthly equivalent); in reality the annual amount is often billed once, upfront. Yearly cost therefore uses the actual annual amount, not the monthly equivalent times twelve.
Can I compare IONITY Motion, Power and an annual subscription?
Yes. Enter each variant as its own tariff scenario with its current base fee and applicable kWh price. IONITY currently offers both monthly and annual subscription variants -- but tariff conditions and prices must always be checked against official current provider information, since they can change.
Can I compare EnBW S, M and L?
Yes, using three tariff cards. Important: enter the price that actually applies to the intended charging scenario (own EnBW network or roaming).
Can I compare Aral pulse tariffs?
Yes, for example a no-fee option and a subscription option -- always using the currently valid official prices.
Why can a tariff with the lowest kWh price still be more expensive?
Because of the subscription fee. At low charging volume, the fixed fee can exceed the savings from the lower price.
Why can a tariff with no base fee become expensive for frequent drivers?
Its higher variable price accumulates with every kWh charged and can eventually exceed the savings from the missing base fee.
What if two tariffs never intersect?
This happens with equal kWh prices (the lower-fee tariff is then always cheaper) or when one tariff is at least as good in both quantities and strictly better in one (dominance). Neither case has a positive break-even.
Does the calculator include blocking or parking fees?
No. They depend on charging duration, dwell time and operator, and do not fit the simple linear tariff model (base fee + kWh price).
Does the calculator include roaming prices?
Only if the user enters the applicable roaming price as the tariff's kWh price.
Why is the price sometimes different at another charging station?
Because of own-network vs roaming terms, different countries, sites, operators, or dynamic pricing.
Does the cheapest calculated tariff automatically mean it is the best tariff?
No. Also consider network coverage, reliability, charging locations, contract duration, app/card access, and roaming conditions. You can, for example, enter EnBW mobility+ L, IONITY Power and Aral pulse Extra as three tariff scenarios -- the calculator answers only the cost question, not network quality.
Which EV charging tariff suits me?
It depends on your public charging volume: occasional public chargers often do better with a no-fee tariff, regular public chargers benefit from a smaller subscription above a certain volume, and frequent drivers usually benefit most from the lowest kWh price, even at a higher base fee. Enter your own values to see the concrete break-even for your case.
Charging tariff with or without a base fee -- which is cheaper?
Below the break-even point the no-fee tariff is cheaper, above it the tariff with a base fee and lower kWh price is cheaper. Break-even follows from E_break = fee difference / kWh price difference, converted to km via the effective consumption.
What should I enter if I mostly charge at home or at work?
Only the distance whose energy is actually charged through the compared public tariffs -- not your total mileage. Example: 1,500 km total distance with only 30% public charging gives a relevant public mileage of 450 km, or 90 kWh/month at 20 kWh/100km.
Is ad-hoc charging or a contract tariff cheaper?
It depends on the specific price and charging volume. Ad-hoc charging can be entered as a tariff with 'No fee' and compared directly against contract or subscription tariffs.
Can I directly compare EnBW mobility+, IONITY and Aral pulse?
Yes, using three tariff cards. Enter each provider's currently valid base fee and the kWh price that applies to your charging scenario -- network coverage and availability are not evaluated.
IONITY monthly or annual subscription -- which pays off more?
It depends on your actual annual charging volume and the currently valid fee. Enter both variants as separate tariff cards (base fee 'per month' or 'per year'); the annual fee is converted to a monthly value for comparison but is often actually billed once, upfront.
Aral pulse Klassik or Extra -- which tariff pays off?
It depends on the break-even between the two variants: fee difference divided by kWh price difference, converted to a monthly charging volume or mileage. Always check and enter the currently valid fees and prices from the provider.
Why doesn't the calculator show every mathematical intersection as a relevant tariff switch?
With three tariffs, two lines can mathematically cross at a point where a third tariff is already cheaper. Such a crossing is mathematically real but not an actual switch point of the cheapest tariff. The calculator therefore only marks the switch points of the lower envelope across all tariffs as relevant.