How do I calculate the cost per day of something I own?

Take the purchase price, subtract what you expect to get back when you sell or trade it in, and divide by the number of days you keep it: (price − resale value) ÷ (years of use × 365.25). A 1,200 phone kept for 3 years with 200 resale value costs about 0.91 per day.

What is cost per use (or cost per wear)?

Instead of dividing by days, you divide by the number of times you actually use the item. A 150 pair of shoes worn 100 times costs 1.50 per wear. It is the honest metric for things you use irregularly — jackets, tools, sports gear.

How do I estimate the lifespan?

Use how long you realistically keep the item, not how long it could theoretically last. Past behaviour is the best guide: if you replace your phone every 3 years, 3 years is your number — even if the phone would survive 6.

Is this calculator free and private?

Yes. It runs entirely in your browser — nothing you enter is sent anywhere or stored. It is built by the makers of whaaat, the iOS app that tracks cost per day permanently for everything you own, with the same privacy promise.

Free tool

Cost per day calculator

The price tag is a moment — owning something is years. Enter what you paid and how long you'll keep it, and see what it really costs you per day, month and year. Or compare a cheap option against a durable one.

Compare two options (cheap vs. durable)

Your item

Purchase price

How long you'll keep it (years)

Resale value at the end (optional)

Uses per week (optional, for cost per use)

Cost per day–

Per month–

Per year–

The calculator is a snapshot. whaaat tracks cost per day permanently — for everything you own.

Runs entirely in your browser — nothing you enter is sent or stored. No account, no cookies.

The honest math

How cost per day is calculated

One purchase, spread over the time you actually keep the thing:

cost per day = (purchase price − resale value) ÷ (years of use × 365.25)

The resale value matters more than most people think: a well-kept item that you sell on isn't an expense of its full price — only of the difference. That's also why durable things with a resale market often beat cheap ones that end in the bin.

Worked examples

Item	Price	Kept for	Resale	Cost per day
Phone	1,200	3 years	200	≈ 0.91
Espresso machine	600	8 years	0	≈ 0.21
Winter jacket	250	5 years	0	≈ 0.14
E-bike	3,500	6 years	800	≈ 1.23

Cost per use: for things you don't use daily

A suit worn twice a year and a pair of everyday sneakers can cost the same per day — and wildly different amounts per use. Enter your uses per week above and the calculator adds the cost per use ("cost per wear" for clothes). It's the better lens for jackets, tools, sports gear and anything occasional.

Frequently asked

How do I estimate how long I'll keep something?

Use your real replacement rhythm, not the item's theoretical lifespan. If you've bought a new phone every three years for a decade, three years is your number. Honest inputs make honest numbers.

Cheap or durable — which is actually cheaper?

Flip on the compare mode above. Divide each option's net price by its lifespan: the 90 boots replaced yearly cost more per day than the 400 pair that lasts seven years. Buying cheap twice is the expensive way to own things.

What about running costs — electricity, insurance, repairs?

This calculator deliberately shows the purchase spread only. For the full picture per item — including what to set aside for the replacement — that's exactly what the whaaat app does, continuously.

Is this calculator private?

Completely. It runs in your browser; nothing is sent, stored or tracked. Same promise as the app: your money is nobody's business but yours.

Know it for everything you own

whaaat turns every purchase into a cost per day, a savings budget and a plan for what's next — private, on your device.

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