# Tail spend calculator

> Paste a supplier spend export and see your tail spend: how much money and how many suppliers sit outside the 80% of spend you manage closely.

Updated 2026-11-06. Source: https://atta.sh/tools/tail-spend-calculator

Paste supplier and amount lines from your accounting export. The calculator sorts suppliers by spend, finds the ones that cover 80% of it, and shows what's left: the tail, in money and in supplier count.

## How the tail is found

Suppliers are sorted from biggest to smallest. Starting at the top, they're added up until they reach the head share, 80% by default. The supplier that crosses the line counts as head. Everyone after it is the tail.

With the sample data, 3 of 13 suppliers make up the head, and the other 10 suppliers are the tail: about 12% of the money and 77% of the supplier list. That's the usual shape. The tail is small in money and large in the number of suppliers, purchases and approvals someone has to handle.

## Getting the data

Most accounting tools export spend by vendor for a period. Keep two columns, supplier and amount, and paste the lines. A header row is skipped, and the same supplier on several lines is added together.

## What to do with the tail

The tail is the purchases nobody negotiates: office supplies, a part for a site, equipment for a new starter. Atta is built for that spend. Requests come in from chat, the agent buys within the rules you set, and every purchase lands on one record. See [tail spend management](https://atta.sh/tail-spend).

## Questions

### What is tail spend?

The part of spend spread across many small suppliers and purchases, usually defined as what's left after the suppliers that make up 80% of spend.

### Is my spend data sent anywhere?

No. It's parsed and added up in your browser.