Home energy decisions should start with understanding—not a sales call.

Home energy is normally divided across separate calculators: one for bills, another for solar, another for a battery, another for an electric car, another for heating, another for tariffs. In a real home those things affect one another.

Your electricity price changes what solar, a battery and home EV charging are worth. Heating can transform your electricity demand. All of those choices can change which tariff suits you. Home by Numbers brings those questions together using one set of household figures, so a change in one place shows up everywhere it matters.

• The calculators are free to use.
• No account, email address or phone number is required.
• Assumptions are visible and editable, so you can replace ours with figures from your own bill.
• You see the result before any commercial link — never the other way round.
• We are willing to say when an option may not be financially worthwhile for you.

Home by Numbers is independent. It is not an energy supplier, an installer or a price-comparison service, and it does not sell your details to anyone.

In future we may include clearly labelled partner links. If you choose to use one and complete an eligible action, we may earn a commission, which helps keep the calculators free. A commercial arrangement never changes a calculation or a result. You can read more in our affiliate disclosure.

Every calculator explains what it does, which assumptions it uses and where its limits are. If you want the detail, see how the calculations work.