What is the difference between a fixed tariff and a variable tariff?

A fixed tariff keeps your unit rates (and usually the standing charge) the same for an agreed term, helping you budget and reducing the risk of price increases during that period. A variable tariff can change over time (up or down), so your bills may move with market conditions and supplier pricing changes.

Which is usually cheaper in the UK: fixed or variable?

It depends on current prices and how long you plan to stay on the tariff. Fixed tariffs can be cheaper when they are priced below expected future rates or when you want certainty. Variable tariffs may be cheaper when prices are falling, but they can rise at any time. Use the comparison table on this page to weigh certainty vs potential savings.

When should I choose a fixed tariff?

Choose a fixed tariff if you want predictable energy costs, prefer budgeting stability, or want to protect yourself against potential price rises. It can also be a good option if the fixed rate is competitive versus your current variable rate.

When should I choose a variable tariff?

Choose a variable tariff if you value flexibility and want to avoid exit fees, or if you believe prices may fall and you’re comfortable with bills changing. A variable option can suit short-term needs while you monitor the market.

Do fixed tariffs have exit fees?

Many fixed tariffs include an exit fee if you leave before the end of the term, though not all do. Always check the tariff details and terms before switching so you understand any potential costs.

Can my fixed tariff price change during the contract?

With a fixed tariff, the unit rates are designed to stay the same for the agreed term. However, some components may still change in certain circumstances (for example, government policy changes or VAT changes). Check the specific tariff terms for full details.

What should I compare besides unit rates when choosing a tariff?

Compare unit rates and standing charges, the tariff length, any exit fees, payment method (Direct Debit vs pay on receipt), customer service, and any additional features. Your usage pattern also matters—high-usage homes are more sensitive to unit rates, while low-usage homes may be more impacted by the standing charge.

How do I know whether fixing now will save me money?

Estimate your annual usage (kWh) for gas and electricity, then apply the unit rates and standing charges for both fixed and variable options to compare total annual costs. The comparison table on this page helps highlight the trade-offs so you can choose the option that best matches your risk tolerance and budget goals.

Is it easy to switch between fixed and variable tariffs?

Switching is usually straightforward, but check whether your current tariff has an exit fee or any notice period. If you want to explore your options, start with the guidance on this page and then review available tariffs on https://www.energyplus.co.uk/.

Best fix vs variable energy tariffs (UK) — comparison table & guide

Compare fixed and variable (including tracker) tariffs side-by-side, with UK-specific caveats on exit fees, smart meters, payment methods and the Ofgem price cap—plus a simple checklist to help you choose.

See a clear fix vs variable comparison table and decision checklist
Get two realistic UK examples with estimated monthly costs (assumptions shown)
Use our whole-of-market comparison to find a tariff that fits your household

Get your energy quote See the fix vs variable table

Estimates only. Tariffs, eligibility, standing charges and unit rates vary by region, meter type and payment method.

Fast answer: should you choose a fixed or variable tariff?

A fixed tariff can suit you if you want bill stability for a set period (often 12–24 months) and you’re comfortable with possible exit fees. A variable tariff (including standard variable and tracker tariffs) can suit you if you want flexibility and to benefit if prices fall, but you must be able to handle price changes (and sometimes more frequent changes on trackers).

Key takeaways (UK-specific)

Ofgem price cap limits the unit rates/standing charges on most default tariffs (SVTs), not on most fixes.
Region and meter type (single-rate, Economy 7, smart, prepay) materially change rates—always compare using your details.
Direct Debit is typically cheapest; pay on receipt of bill can cost more with some suppliers.
Exit fees are common on fixes; many variables have none (but always check the tariff information label).

A quick rule of thumb

Choose fixed if:: you value predictability, you’re staying put, and a slightly higher rate feels worth the certainty.
Choose variable if:: you want flexibility, you may move soon, or you’re comfortable tracking price changes.

Important: the “best” option depends on your actual rates today versus what’s available for your postcode, meter and payment method.

Compare fixed vs variable tariffs for your home

Use your postcode and contact details so we can return results that match your region, meter setup and payment method. This helps avoid misleading “headline” rates that don’t apply to your area.

What you’ll see in your results

Estimated annual cost for your tariff type (fixed, variable, tracker where available)
Unit rates and standing charges, shown clearly
Exit fees and contract length (if applicable)
Eligibility notes (for example: smart meter requirements for some trackers)

Tip: if you can, have a recent bill to hand—your current unit rates and standing charges are the fairest baseline.

Get your quote

How switching typically works in Great Britain

You compare tariffs (fixed, variable, and any eligible tracker options) using your postcode and preferences.
If you choose to switch, your new supplier arranges the transfer—your supply usually stays on while the switch completes.
You’ll receive confirmation of rates, standing charges, contract length and any exit fees.
You may need to provide an opening meter reading (or it may be taken automatically on smart meters).

Northern Ireland has different market arrangements. This page is written for households in Great Britain unless stated otherwise.

Fixed vs variable tariffs: side-by-side comparison (UK)

This table focuses on the features that most often change the real-world cost and experience: how prices change, contract terms, exit fees, and practical eligibility constraints (smart meters, payment types, meter setups).

Feature	Fixed tariff	Variable tariff (SVT)	Variable tariff (Tracker)
How prices change	Unit rate/standing charge fixed for the contract term (unless contract allows changes in specific circumstances).	Supplier can change rates, but typical changes align with the Ofgem cap updates (not guaranteed).	Rate tracks a published index/formula (often changes daily/weekly). Can move up or down.
Protection from spikes	Higher during your fix term (you’re insulated from increases).	Medium—SVTs are generally constrained by the price cap (where applicable).	Lower—may have no cap protection; check tariff terms carefully.
Ability to benefit if prices fall	Usually limited (you keep paying the fixed rate unless you pay exit fees to leave).	Can benefit at the next price change (timing varies).	Often benefits quickly when the index drops (but rises just as quickly).
Contract length	Commonly 12–24 months (sometimes longer/shorter).	No fixed term (ongoing).	Often ongoing, but some have terms or conditions.
Exit fees	Common (often per fuel). Always check before switching.	Typically none.	Often none, but not universal—check terms.
Smart meter requirement	Usually not required (depends on tariff).	Not required (depends on supplier/meter type).	More common to require a smart meter for accurate frequent pricing.
Who it tends to suit	People who want predictable budgeting and plan to stay in the property.	People who prefer flexibility or may switch again soon.	People who can tolerate rate movement and want close-to-market pricing.

The Ofgem price cap applies to standard variable and other default tariffs for most households in Great Britain. It does not automatically make SVTs “cheap”—it’s a limit, not a discount.

Decision checklist: which tariff type is best for you?

A fixed tariff may suit you if…

You want stable bills for a set period.
You’d rather avoid short-notice price rises.
You’re happy to commit and you understand any exit fees.
You can pass a basic affordability check if a supplier requires it (some do, some don’t).

A variable (SVT) may suit you if…

You want flexibility (typically no exit fees).
You might move home soon.
You want the reassurance that most SVTs are constrained by the Ofgem cap.
You’re waiting for a better fixed deal and don’t mind price changes.

A tracker may suit you if…

You’re comfortable with rates moving (sometimes daily).
You check how the tracker is calculated and any caps/floors.
You have (or can get) a suitable smart meter if required.
You want the possibility of benefiting quickly if wholesale-linked prices fall.

Often not ideal if…

Fixed: you may move soon, or exit fees would be painful.
SVT: you need tight budgeting certainty month-to-month.
Tracker: you’d struggle with sudden price rises or prefer not to monitor rates.

What to check before you decide

Are rates shown for your payment method (Direct Debit vs pay on receipt)?
Do you have Economy 7 or a single-rate meter (and are you comparing the right tariff type)?
Any exit fees, and are they per fuel?
Any eligibility constraints (smart meter, prepay, credit history checks)?

Costs, exclusions and common pitfalls (so you don’t get caught out)

Energy comparisons can look straightforward, but real bills are driven by a few details. These are the most common reasons people choose a tariff that isn’t actually best for them.

1) Comparing the wrong meter type

If you have Economy 7 (two rates: day/night), comparing against a single-rate tariff can distort estimates. The “best” tariff depends on how much you use at night versus day.

2) Exit fees on fixes

A fixed deal may look cheaper, but if you leave early you could pay an exit fee per fuel. Factor this into any “break-even” calculation—especially if you might move.

3) Standing charges are doing the damage

Two tariffs can have similar unit rates but different standing charges. If you’re a low user (small flat, away often), standing charges can dominate the bill.

4) Payment method differences

Some tariffs price differently for Monthly Direct Debit versus pay on receipt of bill. Always compare using how you actually pay (or plan to pay).

Two scenarios with numbers (illustrative, not a quote)

Scenario A: renter likely to move within 9 months

Assumptions: Great Britain, dual fuel, Monthly Direct Debit. Electricity use 2,400 kWh/year; gas use 8,000 kWh/year (typical smaller household). Example standing charges: electricity 55p/day, gas 30p/day.

Option	Example unit rates	Estimated monthly cost
Variable (SVT)	Elec 26p/kWh, Gas 6.5p/kWh	~£106/month
12-month fix	Elec 28p/kWh, Gas 7.0p/kWh	~£114/month

If the fixed tariff has an exit fee (for example £50 per fuel), moving early could add ~£100, which may outweigh any benefit unless the fix is clearly cheaper.

Scenario B: family homeowner prioritising stability

Assumptions: Great Britain, dual fuel, Monthly Direct Debit. Electricity use 3,100 kWh/year; gas use 12,000 kWh/year. Same example standing charges as above.

Option	Example unit rates	Estimated monthly cost
Variable (SVT)	Elec 26p/kWh, Gas 6.5p/kWh	~£146/month
24-month fix	Elec 27p/kWh, Gas 6.6p/kWh	~£149/month

Even if the fixed deal is slightly higher in this illustration, some households prefer it because it reduces the risk of higher bills if variable rates rise during the term.

These scenarios use rounded example rates to demonstrate how the maths works. Your results can differ materially by region, tariff availability, standing charges, discounts, and your exact usage split.

Common exclusions & special cases

Prepayment meters: tariff choice can be more limited, and the price cap has a specific level for prepay customers.
Complex meters (e.g. multi-rate / restricted meters): you may need specialist tariff support—flag this when comparing.
Switching while in debt: rules vary; you may be blocked from switching in some circumstances. Seek supplier advice if you’re unsure.
Warm Home Discount / Priority Services Register: benefits are typically not dependent on fix vs variable, but eligibility and delivery can differ by supplier.

FAQs: fixed vs variable energy tariffs (UK)

Is a fixed tariff always cheaper than a variable tariff?

No. A fixed tariff buys you certainty, not guaranteed savings. Sometimes fixes are cheaper than a variable tariff; sometimes they’re higher. Always compare using your postcode, meter type and payment method.

What is the Ofgem price cap, and does it make variable tariffs “safe”?

The cap limits the maximum unit rates and standing charges suppliers can charge on most default tariffs for typical customers in Great Britain. It can still go up or down, and it doesn’t guarantee the lowest deal—only a regulated limit.

Are tracker tariffs capped by Ofgem?

Not usually. Some trackers include their own caps or protections, but many don’t. Check the tariff’s terms and how the tracking formula works before switching.

Can I switch a fixed tariff before it ends?

Usually yes, but you may pay an exit fee. Exit fees are often charged per fuel (gas and electricity). Check your tariff information and the timing—some suppliers reduce or waive exit fees near the end of the term.

Does my region affect the price a lot?

Yes. Standing charges and unit rates vary by region because network costs differ. That’s why postcode-based comparisons are essential for an accurate fix vs variable decision.

Will I need a smart meter to get the best deal?

Not always. Many fixed and standard variable tariffs don’t require a smart meter. However, some trackers and time-of-use tariffs may require one to measure usage accurately.

Is Direct Debit always cheaper?

Often, but not universally. Many suppliers price Monthly Direct Debit lower than paying on receipt of bill. If you can’t use Direct Debit, filter your comparison to match your payment method so the estimate stays realistic.

What if I’m on a prepayment meter?

You can still compare, but tariff availability may be more limited, and prices can differ. If you’re looking to move from prepay to credit meters, ask your supplier what’s required and whether any debt needs clearing first.

Trust, methodology and sources

Editorial details

Written by:: EnergyPlus Editorial Team
Reviewed by:: Energy Specialist
Last updated:: March 2026

How we assess “fixed vs variable” for UK households

We focus on factors that change outcomes for real homes, not just headline prices:

Total cost drivers: unit rates and standing charges for gas and electricity.
Risk and predictability: how and when prices can change.
Contract terms: length, exit fees, and switching flexibility.
Eligibility constraints: meter type (single-rate/Economy 7), smart meter requirements, and payment method pricing.
Regulation context: how the Ofgem price cap affects default tariffs for most GB households.

Limitations: This guide uses illustrative examples and can’t account for every tariff rule or personal circumstance (e.g. complex meters, debt-related switching restrictions, supplier-specific credit checks). Always read the tariff information before you agree to switch.

Sources (UK)

Ofgem (Great Britain energy regulator) — price cap and consumer guidance.
Citizens Advice: energy supply and switching advice.
GOV.UK — general UK government guidance and services (including support schemes where applicable).

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Updated on 19 Mar 2026