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kWh: What It Is and How It Translates to Euros on Your Bill
Respuesta rápida
A kilowatt-hour (kWh) is a unit of energy representing the consumption of 1,000 watts over one hour. In the Spanish electricity market, this measurement determines the variable portion of your bill, where the price per kWh fluctuates based on your contracted rate and the wholesale market hourly costs.
En 30 segundos
- ✓Locate the 'Consumption' section in your PDF bill
- ✓Check the price per kWh for each period (P1, P2, P3)
- ✓Multiply kWh by the unit price to verify the subtotal manually
Stop guessing, start auditing
Upload your bill and get a forensic breakdown of your kWh costs in 30 seconds. No calls, no spam.
Why you can trust it
- Free and no signup
- AI trained on the Spanish market (~30s)
- Privacy-first: ephemeral processing (we don't store your bills)
Transparencia y fuentes
Authorship, methodology and official sources.
Actualizado: 10 de enero de 2026
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Transparencia y fuentes
Authorship, methodology and official sources.
Actualizado: 10 de enero de 2026
Autoría
Equipo ahorr.ai
Auditoría energética (España)
Metodología orientada a decisión: separar coste fijo/variable, detectar extras y comparar opciones con números claros.
Metodología
- →Separamos coste fijo (potencia/término fijo), energía y cargos/impuestos.
- →Buscamos sobrecostes típicos: potencia sobredimensionada, servicios extra, lecturas estimadas.
- →Damos pasos accionables (qué tocar primero) con ejemplos orientativos, no promesas.
- →Enlazamos fuentes oficiales y marcamos lo que puede variar por comercializadora.
Información orientativa (España). Comprueba condiciones con tu comercializadora: precios, peajes, cargos e impuestos pueden variar.
kWh: What it is and how it translates to euros (without the jargon)
To understand your bill, you must first separate power from energy. While power (kW) is the size of the pipe, energy (kWh) is the amount of water that flows through it.
The definition in one sentence
A kilowatt-hour is the amount of energy used by a 1,000-watt appliance running for one hour.
Where it appears on the bill
Look for the 'Facturación por energía consumida' section. This is where your provider multiplies your consumption by the agreed price.
Why it matters (money, decisions, and typical traps)
The kWh price is the most manipulated variable in the energy market. A difference of just 0.02€ per kWh can result in hundreds of euros of difference per year.
The most common error
Many users focus on the total amount without checking the unit price. Providers often hide price hikes behind 'discounts' on the fixed term.
The clue almost nobody looks at
The 'Effective Price'. If you divide your total bill by the kWh consumed, you'll see the real cost of your energy, including all the hidden 'vampire' services.
How to check it in 60 seconds (Auditor's Checklist)
You don't need to be an engineer to find the leaks in your bill. You just need to know where to look.
What to look for in the PDF
Identify the breakdown of periods P1 (Peak), P2 (Flat), and P3 (Valley). If you consume most of your energy in P1 but pay a single price, you are likely overpaying.
What to note down to compare
Keep track of your total kWh per month. If it spikes without a change in habits, your meter or a specific appliance might be failing.
If you want certainty: Autopsy your bill and decide with numbers
Manual checks are good, but a forensic audit is better. We look for the fingerprints of overcharging that are invisible to the naked eye.
What ahorr.ai detects
We identify oversized power contracts, vampire services hidden in the fine print, and compare your current rate against the top 3 cheapest tariffs in Spain.
- ✓Oversized power detection
- ✓Hidden service identification
- ✓Real-time market comparison
What to do with the result
Once you have the data, the choice is yours. You can switch providers in minutes or simply adjust your current contract to stop the leak.
Forensic Checklist: Auditing Your kWh
- ✓Locate the 'Consumption' section in your PDF bill
- ✓Check the price per kWh for each period (P1, P2, P3)
- ✓Multiply kWh by the unit price to verify the subtotal manually
- ✓Identify if taxes (VAT and Electricity Tax) are applied correctly to the energy sum
- ✓Compare the total kWh consumed with the previous month's history to find anomalies
kWh to Euro Conversion Glossary
| Term | Definition | Impact on Bill |
|---|---|---|
| kWh (Kilowatt-hour) | Unit of energy consumed over one hour | Directly affects the variable part of your bill |
| Unit Price (€/kWh) | The cost agreed with your provider per unit | Determines how much each appliance costs to run |
| Contracted Power (kW) | The capacity available to use simultaneously | A fixed daily cost regardless of consumption |
| Effective Price | Total cost divided by total kWh | The real price you pay after all fees and taxes |
The effective price is the only way to truly compare different tariffs accurately.
The Case of the Growing Fixed Fee
A small business owner in Spain noticed their monthly payments were creeping up despite similar usage. Upon forensic inspection, we found they had 4.6 kW of contracted power but never exceeded 2.8 kW. More importantly, their effective price per kWh was inflated by hidden services that added no value to their operation.
Hallazgos
- ✓Contracted power 4.6 kW vs 2.8 kW peak usage
- ✓Hidden service fee of €6.99/month found in the small print
- ✓Effective price of €0.23/kWh including taxes vs market average
Stop guessing, start auditing
Upload your bill and get a forensic breakdown of your kWh costs in 30 seconds. No calls, no spam.
Related guides
Preguntas frecuentes
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Disclaimers
- Informational tool; not financial advice.
- We don’t guarantee savings: these are estimates.