# What units cost: the bill with worked numbers
The numbers on this page use an **example plan at EUR 7.20 per month that includes one unit**. Your plan's real price is on its page, and the quote endpoint returns your exact figures before you commit to anything.

## The rule

1. The plan's monthly price covers the units **included** in the plan (normally one). It is paid up front, like any subscription.
2. Every unit **above** the included ones is an **extra unit**. It is billed for the hours it actually runs, at the plan's monthly price divided by 720, with no surcharge.
3. Each time an extra unit starts, it is billed for **at least 5 minutes**.
4. Extra units are added up per calendar month (UTC) and invoiced after the month ends.

This is the same for a fixed policy and an autoscaled one. There is no separate multiplied price for "3 units".

## The rate

```text
extra unit-hour = plan monthly price / 720
EUR 7.20 / 720  = EUR 0.01 per extra unit-hour
```

720 is 30 days of 24 hours. A whole 30-day month of one extra unit costs exactly the plan price.

## Worked examples

**A. One unit, nothing else.** You pay EUR 7.20. No extra units, no metering.

**B. Fixed at 3 units for a whole 30-day month.** One unit is included, two are extra:

```text
2 extra units x 720 hours x EUR 0.01 = EUR 14.40
EUR 7.20 + EUR 14.40                  = EUR 21.60
```

**C. Autoscaled 1 to 4, a quiet month with two busy days.** On one day it ran 2 extra units for 6 hours; on another, 1 extra unit for 3 hours:

```text
(2 x 6) + (1 x 3)   = 15 extra unit-hours
15 x EUR 0.01       = EUR 0.15
EUR 7.20 + EUR 0.15 = EUR 7.35
```

**D. A very short start.** An extra unit that runs 90 seconds is billed 5 minutes:

```text
5 / 60 hours x EUR 0.01 = EUR 0.00083
```

This minimum is why a policy that flaps up and down is more expensive than one that holds steady, and why the cooldown settings exist.

**E. A public port.** Raw ports are billed by the hour they are held, capped at one port-month. At an example price of EUR 1.00 per port-month, a port held 72 hours costs `72 / 720 x 1.00 = EUR 0.10`, and a port held all month costs EUR 1.00. HTTPS endpoints are free. Ports are billed in arrears together with the extra units.

## The worst case, before you save

`POST .../units/policy/quote` takes the same body as the policy update and returns what it could cost at most, without saving it. For autoscaled between 1 and 4 units on the plan above:

```text
extra_units        = 3              (4 max minus 1 included)
hourly_cents       = 1              (EUR 0.01 per extra unit-hour)
worst_case_hours   = 3 x 744 = 2232 (the longest month, 31 days)
worst_case_cents   = 2232           (EUR 22.32)
```

If you also set `spend_cap_cents` to 1500, `monthly_cents` is 1500 and `cap_binds` is true. The worst case is rarely reached; it is the number that cannot be exceeded.

## The spend cap

`spend_cap_cents` limits how much extra units may cost in a month. At or over it, scaling refuses to grow, and records why. It never stops a running unit.

Organizations without a credit limit hold a **wallet reservation** for the cap while scaling is on, so the end-of-month invoice can always be paid. If your available balance cannot cover it, turning scaling on is refused with the amount you need. A running Workload is never stopped for this.

## Reading your bill

The units chart (`GET .../units/count`) is drawn from the same records the invoice is built from: how many units ran, how many were billed as extra, and why the count changed. If a number on the invoice surprises you, the chart for the same month explains it.

A unit that is scaled away stops billing at that moment.