# The Inbox Time-Cost Calculator — Zen Inbox Cleaner

Last reviewed: August 30, 2026. HTML version: https://zeninboxcleaner.com/tools/inbox-time-calculator

How much of your year goes to email you never wanted? Choose your numbers — every assumption is yours to set.

The calculator runs entirely in your browser. The numbers you pick never leave the page: there is no form submission, no network request, no cookie, and nothing stored. This mirror states the whole model in plain text so you can check the arithmetic — or do it yourself — without running the tool.

## What you give it

- **Emails you receive per day** — a count you type. Presets are offered for **20 · 50 · 100 · 200**.
- **How much of it is unwanted?** — about a quarter (**25%**), about half (**50%**, the default), or most of it (**75%**).
- **Seconds each unwanted email steals** — **2** (a glance and a swipe), **5** (read a bit first, the default), or **10** (open, scroll, hunt the unsubscribe link).

Nothing is measured for you and nothing is guessed on your behalf: the three inputs are the three assumptions, and they are all yours.

## The formula

With `perDay` = emails received per day, `pct` = the unwanted share, and `secs` = seconds each unwanted email steals:

```
unwantedPerYear = perDay × 365 × pct
secondsPerYear  = unwantedPerYear × secs
hoursPerYear    = secondsPerYear ÷ 3600
workWeeks       = hoursPerYear ÷ 40   (shown only at 40 hours or more)
```

Hours are shown to one decimal place, and so are work-weeks.

Worked examples:

- **100 emails a day, half unwanted, 5 seconds each** → 100 × 365 × 0.5 = **18,250** unwanted emails a year → × 5 = **91,250 seconds** → **≈ 25.3 hours a year**. Under 40 hours, so no work-week line.
- **200 a day, 75% unwanted, 10 seconds each** → **54,750** emails → **547,500 seconds** → **≈ 152.1 hours a year** → **≈ 3.8 work-weeks**.

## The assumptions, stated plainly

- **A year is 365 days** — every day, because unwanted mail does not take weekends.
- **A work-week is 40 hours**, and the work-week line only appears once the yearly total reaches 40 hours.
- **The seconds figure counts handling time only** — glancing, swiping, hunting an unsubscribe link. It does not count the time it takes to get back to what you were doing; leaving that out keeps the estimate conservative.
- **This is an estimate, nothing more.** Every number in it was chosen by you, and changing any one of them changes the answer.

## What we make of the number

| Hours per year | Line |
|---|---|
| Under 10 | Barely a dent. Guard it anyway. |
| 10–39 | A full workday or more, every year, on mail you never asked for. |
| 40–99 | That's ≥ a work-week a year of deleting and scrolling. |
| 100 and up | Weeks of your year. The unsubscribe button is a raise. |

Storage is a different question from time: for that, see the Email Hoarder Calculator (https://zeninboxcleaner.com/tools/email-hoarder-calculator) or the one-minute storage diagnosis (https://zeninboxcleaner.com/tools/storage-diagnoser).

## Get those hours back.

Zen Inbox Cleaner groups your Gmail inbox by sender, so you can trash bulk mail, newsletters, and promotions in one tap — and unsubscribe with one tap. It reads email metadata only (never bodies or attachments), everything happens on your device, and nothing is permanently deleted by the app — trashed email stays recoverable in Gmail's Trash for 30 days.

Its auto-trash rules are native Gmail filters — they run inside Gmail itself, so the flood stays stopped.

Get the app: https://zeninboxcleaner.com/#get · How it works: https://zeninboxcleaner.com/#how-it-works