# monthly instalments are credit, priced at an APR
How to calculate insurance premium
Insurance premiums are quoted as a rate per unit of cover, with insurance premium tax added on top. Paying monthly is a credit agreement, not a payment option, which is why the total exceeds the annual price.
IPT is 12% at the standard rate in the UK and 20% on travel and some vehicle policies. It applies to the premium, not the cover, and appears in every quote you are shown.
What to enter:
Sum insured
Rate per £1,000 of cover — insurers price in units; 1.6 means £1.60 per £1,000
Insurance premium tax(%)
Instalment APR(%) — what monthly payment costs compared with paying once
Everything recalculates as you type, and the numbers in the address bar update with it, so a link to this page carries your figures with it.
The order the fields are filled in makes no difference to the result — the calculator recomputes the whole formula from whatever is currently in every field, not step by step. That means it is safe to adjust one number, watch the result change, and adjust it back, without worrying about resetting anything first.
Why insurance premium matters
The formula behind insurance premium is standard and has not changed in decades; what changes is the situation it gets applied to. Two households can run the identical calculation and land on very different conclusions once their own numbers — income, rate, term, balance — are dropped in, which is why a generic textbook example is less useful than a calculator you can adjust to match your own circumstances.
Beyond a one-off check, the same calculation is worth revisiting whenever the underlying numbers change — a new interest rate, a change in income, a different term. Because the figures live in the page's own web address, coming back to update just one field and compare the new result against the old one takes seconds rather than starting again from a blank page.
It is also worth being clear about what a single figure like this can and cannot settle on its own. It answers the specific question the formula was built to answer, and nothing more — a favourable insurance premium result does not automatically mean a decision is a good one overall, since plenty of other factors that a formula cannot capture, from personal circumstances to how comfortable a commitment feels, usually matter just as much as the arithmetic. Use the number as one solid input among several rather than the whole of the decision.
A calculator like this one is often bookmarked and returned to repeatedly over months rather than used once, particularly for anything tied to an ongoing plan such as a mortgage, a savings goal or an investment being tracked. Because the figures live in the web address rather than only in memory, coming back to the same page with updated numbers is quicker than starting from a blank spreadsheet each time.
Worked example
A concrete run-through, using the values already in the fields:
Sum insured: 250,000
Rate per £1,000 of cover: 1.6
Insurance premium tax: 12 %
Instalment APR: 22 %
That gives:
Annual premium including tax: 448
Monthly instalment: 41.93
Extra cost of paying monthly: 55.16
These figures are only the calculator's own starting values, included so the working is visible rather than hidden inside the tool above. Replace them with your own numbers and the same arithmetic applies — nothing about the method changes, only the inputs feeding it.
Reading the result
The instalment cost line is what monthly payment adds. At a typical 20–25% APR it is around 10–12% of the premium — for a £400 policy, roughly £45 a year for the convenience.
Where this goes wrong. Auto-renewing. Insurers price renewals above new-business quotes, and the same insurer will often quote materially less through a comparison site than in your renewal letter.
A useful check on any unfamiliar result is to compare it against a rough mental estimate first — round the inputs to convenient numbers and see whether the calculator's answer lands in roughly the same territory. A wildly different figure usually means one of the fields was entered in the wrong unit, most often a percentage typed as a whole number where a decimal was expected, or the reverse.
Because it is a loan. The insurer or a finance partner advances the annual premium and you repay it with interest, typically at an APR of 20–30%.
A tax on general insurance premiums, currently 12% standard rate and 20% higher rate in the UK. It is not VAT and cannot be reclaimed by VAT-registered businesses.
It returns annual premium including tax. With 250,000 sum insured, 1.6 rate per £1,000 of cover and 12 % insurance premium tax, that comes to 448. Change any field and the figure moves with it.
Whenever one of the underlying figures changes — a new interest rate, a different balance, an updated term — since the result only reflects what is currently in the fields. There is no need to keep a separate record of past results; the web address for a filled-in version already carries the figures used to produce it.
Not unless a tax rate or a fee is explicitly one of the inputs above. Where it is not, the figure shown is a gross calculation, and any tax due depends on your personal circumstances and current tax rules, which are worth checking separately.
The arithmetic itself is exact — the calculator applies the formula shown above precisely, with no rounding until the final figure is displayed. The uncertainty, where it exists, is entirely in the inputs: an estimated rate or an approximate balance carries that same approximation through to the result.
