How we calculate

This page sets out every formula the calculators use. Rates and rules come from official sources (HMRC, GOV.UK, Ofgem); prices come from providers' published price lists. Each is stored with its source and check date, and the site can't be published while any figure it displays is unverified. The calculations are unit-tested on every build. The site is maintained by Oliver Burton (about).

Business energy

• Energy = annual kWh × unit rate. Standing charge = 365 × daily standing charge.
• De minimis: if average daily use is at or below 33 kWh (electricity) or 145 kWh (gas), the supply counts as qualifying use: no Climate Change Levy, and VAT at the qualifying rate. In Great Britain, qualifying electricity is zero-rated from 2026-10-01 to 2027-03-31; otherwise the reduced rate of 5% applies.
• Above de minimis: CCL = kWh × the CCL rate in force on today's date, and VAT at 20% on energy + standing charge + CCL.
• From a monthly bill: annual kWh = (monthly bill × 12 ÷ (1 + VAT) − standing charges) ÷ (unit rate + CCL), trying the standard-rated case first.
• Saving per 1p/kWh = kWh ÷ 100 × (1 + VAT). Cost per day open = annual cost ÷ (days a week × 52).
• Comparison with market rates is shown only when we hold a sourced, dated reference rate.

Out-of-contract and broker commission

• Extra cost of current rates = annual kWh × (current rate − contract rate), using both rates you enter, before VAT.
• Broker commission = annual kWh × uplift ÷ 100 per year, × contract years for the total.

Card fees

For each provider: monthly cost = monthly fee + reader rental + Σ over in-person and online (takings × rate + payments × fixed fee), with any Amex share at the Amex rate. Ranked by cost over the chosen period including any one-off reader price. Commission never affects the order. If you tell us your current provider, the saving is the difference between its cost and the lowest.

Broadband and phone

Current cost = 12 × (broadband + line rental + calls). VoIP estimate = 12 × (users × per-user price + broadband plan + static IP and backup if needed). The estimate uses reference prices from a named provider's published business price list.

Total bill check

Reads the results you saved in your browser, sorts by estimated saving (largest first), then by annual cost. Nothing is sent to us.

What we leave out

Metering and network charges billed separately, half-hourly capacity charges, one-off setup or installation fees, and exit fees from your current contracts. Real quotes may differ.