Underinsurance is when you insure your property for less than it would cost to replace. It’s one of the most expensive mistakes you can make with insurance.
How Underinsurance Works
| Insured For | Actual Value | Payout on Total Loss |
|---|---|---|
| £100,000 | £200,000 | £50,000 (50% of claim) |
| £300,000 | £400,000 | £75,000 (75% of claim) |
| £150,000 | £150,000 | £150,000 (full claim) |
Most insurers apply “average” — if you’re underinsured, they reduce every claim proportionally.
The Average Clause
| Insured Value | True Value | Claim Amount | Payout |
|---|---|---|---|
| £50,000 | £100,000 (50% under) | £20,000 | £10,000 (50%) |
| £50,000 | £100,000 (50% under) | £5,000 | £2,500 (50%) |
Every claim is reduced by the same percentage.
What People Commonly Underinsure
| Item | Typical Value | Often Insured For |
|---|---|---|
| Living room contents | £10,000 | £3,000 |
| Kitchen contents | £8,000 | £2,000 |
| Electronics | £5,000 | £1,000 |
| Wardrobes | £5,000 | £1,000 |
| Total | £50,000 | £15,000 (70% underinsured) |
How to Calculate Correct Cover
Buildings
| Step | Action |
|---|---|
| 1 | Use the BCIS calculator for rebuild cost |
| 2 | Add professional fees (architect, surveyor) |
| 3 | Add demolition and site clearance |
| 4 | Include outbuildings, walls, fences |
Contents
| Room | Typical Value |
|---|---|
| Living room | £5,000-£15,000 |
| Kitchen | £3,000-£8,000 |
| Each bedroom | £2,000-£5,000 |
| Bathroom | £500-£2,000 |
| Hall/landing | £500-£1,000 |
Walk through each room with a notebook. Total everything.
Items That Add Up
| Category | Typical Omission |
|---|---|
| Clothing and shoes | Often underestimated by £2,000+ |
| Jewellery and watches | Valued items need specifying |
| Kitchen appliances | Fridge, washing machine, oven |
| Electronics | TV, laptop, tablet, phone, console |
| Garden equipment | Bikes, tools, furniture |
| Hobby equipment | Sports gear, musical instruments |
| Books and media | Can total £1,000+ |
The 1-in-10 Check
As a quick rule: if you’d struggle to replace 1 in 10 of your belongings, you’re probably underinsured. Most people are underinsured by 30-50%.
How to Fix Underinsurance
- Do a room-by-room inventory — List everything
- Photograph or video — Visual evidence for claims
- Keep receipts — Proof of value for expensive items
- Review annually — Add new purchases
- Update after Christmas/birthdays — New gifts add up
Bottom Line
Underinsurance is the most common insurance mistake. Most people are underinsured by 30-50%. Do a proper inventory, insure for the full replacement value, and review annually. The few extra pounds in premium is worth the peace of mind that you’ll get paid in full.
What to remember about underinsurance
Underinsurance is the gap between what you are insured for and what it would actually cost to replace your property or belongings. Most insurers apply an “average clause” — if your property is worth £200,000 but you are insured for £100,000, every claim is reduced by 50%. This means a £20,000 claim pays only £10,000, and a total loss pays only £50,000 instead of the full £100,000 you expected. The rule is harsh but consistent: the insurer pays proportionally to what you declared, not what you lost.
Most people are underinsured by 30-50%, and the underinsurance is almost always unintentional. Common omissions include clothing and shoes (typically underestimated by £2,000 or more), kitchen appliances, garden equipment, and hobby gear. Walk through each room with a notebook and add up the replacement cost of everything — you will almost certainly be surprised by the total. For buildings, use the BCIS rebuild calculator and add professional fees, demolition costs, outbuildings, walls, and fences. The rebuild cost is not the market value, and getting the two confused is the single most expensive mistake homeowners make.
Errors that leave you underinsured
The most damaging error is insuring your home for its market value rather than its rebuild cost. Market value includes land, which does not need insuring. A property worth £450,000 on the market may have a rebuild cost of only £250,000 — insuring for the higher figure wastes premium, but insuring for a guessed figure that is too low triggers the average clause at claim time. A second common mistake is not doing a room-by-room contents inventory. People remember the big-ticket items — the television, the sofa, the laptop — but forget the contents of wardrobes, kitchen drawers, cupboards, and the loft. Clothing and shoes alone are typically underestimated by £2,000 or more.
A third error is not updating your cover after purchases or home improvements. New furniture, electronics, Christmas gifts, and home extensions all increase the value of what needs insuring. If you extend your kitchen or convert your loft and do not tell your insurer, you may be underinsured at the exact moment you need cover the most. Jewellery and watches worth more than the standard single-item limit (typically £1,000-2,500) need to be specified separately on your policy — without this, a stolen engagement ring will not be fully reimbursed. Finally, not reviewing your cover annually means you drift further from the correct figure each year as prices rise and you acquire more belongings.
Steps to fix underinsurance today
Start with a room-by-room inventory. Take a notebook or your phone into every room, open every drawer and cupboard, and list everything you would need to replace. Photograph or video the contents — this also creates evidence for future claims. For each item, estimate what it would cost to buy new today, not what you paid for it. A five-year-old sofa that cost £800 may cost £1,200 to replace with an equivalent new one, because “new for old” cover replaces items at current prices.
Keep receipts and serial numbers for expensive items, and store copies securely outside your home — a cloud folder or with a trusted family member works well. Re-do the inventory annually, particularly after Christmas, birthdays, or any significant purchase. For buildings, check the BCIS rebuild cost calculator every few years or after any home improvement. The few extra pounds in premium for accurate cover is insignificant compared to the shortfall you face at claim time if you are underinsured. Underinsurance is the most common insurance mistake, but it is also one of the easiest to fix with a methodical approach and honest assessment of what you own.