What this calculator works out
This calculator values an unbuilt kit collection, adds a collectable uplift and the extras typically bought alongside each kit, applies an insurance buffer, and works out how many years the stash would take to build at your current rate.
That last figure is the one people remember. Most modellers have never calculated it.
Stash details
Collector note
This estimates replacement value, not resale value. Keep photos and a list of rare kits if the collection is insured.
Before you total it up
- Average kit value should be what replacing them would cost now, not what you paid. Out-of-production kits frequently appreciate.
- The collectable uplift covers rare, limited-run and discontinued kits sitting above the average.
- Extras per kit means aftermarket decals, photo-etch, resin and masks — routinely a third of a kit's price again.
- The insurance buffer allows for the gap between a valuation and replacement cost at auction prices.
Modellers, knitters and quilters all describe the same condition: acquiring materials faster than they can be used. Among modellers the running joke is a stash acquired beyond life expectancy. The years-to-build figure turns a joke into an arithmetic result, which is either reassuring or clarifying depending on the number.
How this calculator works
A valuation and a build horizon:
Base value = kits × average value × (1 + uplift ÷ 100)
Extras = kits × extras per kit
Total = base + extras
Insured value = total × (1 + buffer ÷ 100)
Years to build = kits ÷ kits built per yearThe insured figure is what to declare on a contents policy, not the total. Most home insurance treats a collection above a threshold as a specified item needing separate listing, and an undeclared collection may not be covered at all.
Worked example: 120 kits
Using the default figures — 120 kits averaging £25, a 15% collectable uplift, £6 of extras each, 8 built a year, a 20% insurance buffer:
- Base value: £3,450
- Extras: £720
- Total: £4,170, insured at £5,004
- Years to build: 15
Two figures worth sitting with. Five thousand pounds is well above most contents policies' single-collection limit, which means the stash probably needs specifying rather than assuming. And fifteen years is fifteen years — at eight kits a year, buying a tenth kit this year adds more than a year to the horizon.
Common mistakes
- Valuing at purchase price. Discontinued kits often cost far more to replace.
- Not declaring the collection to an insurer. It may fall outside single-article limits.
- Forgetting the aftermarket. Extras can add a third to a kit's cost.
- Ignoring storage conditions. Damp and heat damage boxes, decals and vinyl parts.
- Using an optimistic build rate. Use what you actually completed last year.
Frequently asked questions
Should I insure a model collection?
If it is worth more than your policy's single-article or collection limit — commonly £1,000 to £2,500 — then yes, it needs specifying. Insurers usually want a valuation or an itemised list with photographs for anything substantial. An undeclared collection can be settled at the limit rather than its value.
Do model kits hold their value?
Some do, considerably. Discontinued and limited-run kits from respected manufacturers can appreciate well above their original price, and certain vintage kits are sought after. Most mainstream current-production kits do not, and a stash bought at retail is generally worth less than it cost. The collectable uplift is for the minority that appreciate.
How should kits be stored?
Flat, dry, out of direct sunlight and at a stable temperature. Decals deteriorate with age and humidity and are the first thing to fail — many older kits need replacement decals regardless of storage. Loft storage is common and is the worst option because of the temperature swings.
Is a large stash a problem?
Only if it bothers you, or if it represents money you need. Many modellers keep a stash deliberately, so that a subject is always available when the mood strikes, and treat it as a library rather than a backlog. The years-to-build figure is a fact rather than a judgement.
Is what I enter stored?
No. Figures are processed in your browser and never transmitted or retained.
Related tools
References
- Financial Conduct Authority — insurance regulation, underinsurance and specified items
- MoneyHelper — insuring collections and valuables
Sources are checked at publication and can change — how I choose and check references.