# What is Loadster Fuel and how does it work?

> Loadster Fuel is usage-based pricing for load tests and monitoring. Usage is duration × launched bots × bot type. Protocol is 1x; real browsers are 4x.

Source: https://loadster.com/faqs/what-is-loadster-fuel/

Loadster Fuel is the usage currency for [load testing](https://loadster.com/pricing/) and [site monitoring](https://loadster.com/synthetic-monitoring/).
You buy fuel (or get it with a monthly plan), and bots burn it while they run.

It is not a seat license. Editing scripts, designing scenarios, and reading reports don't burn any.
You only pay for the bots that actually generate traffic.

Every new account starts with 50 free units. No credit card required.

## How Loadster Fuel usage is calculated

Usage is roughly:

```text
fuel ≈ duration × launched bots × bot type
```


Duration is how long the bots run. Launched bots is how many bots you start.
Bot type is a multiplier:

* [Protocol Bots](https://loadster.com/manual/protocol-scripts/) burn **1×** (1 unit of fuel per bot-hour)
* [Browser Bots](https://loadster.com/manual/browser-scripts/) burn **4×** (4 units of fuel per bot-hour)
* [Playwright scripts](https://loadster.com/manual/playwright-scripts/) burn **4×** (4 units of fuel per bot-hour)

A Protocol Bot running for one hour burns 1 unit of fuel. 100 Protocol Bots running for 30 minutes burn 50 units of fuel,
which is the free starter amount. The same test with Browser Bots burns 200 units of fuel.

You can mix bot types in one test. Each bot group burns fuel at its own multiplier.

The [fuel calculator](https://loadster.com/pricing/#calculator) on the pricing page does this math as you change duration,
bot count, and bot type. For monitoring, it uses the same formula with one bot per cycle and whatever
schedule you pick.

## How Loadster Fuel compares to VU-hours

VU-hours (virtual user hours) are the unit a lot of load testing tools use: one virtual user running
for one hour.

In Loadster, one unit of fuel is one Protocol Bot running for one hour. So for Protocol Bots, 1 unit of fuel ≈ 1 VU-hour.

Browser Bots and Playwright scripts are still one bot (one virtual user) each, but they burn 4 units of fuel per
bot-hour. If you are converting a VU-hour quote from another tool, count Protocol Bots 1:1 and multiply
real browser bots by 4.

Loadster doesn't sell a separate VU-hour product. Your fuel balance is those bot-hours after the
bot-type multiplier.

## Why Browser Bots and Playwright scripts burn more fuel

Browser Bots and Playwright scripts each drive a real Chrome browser. That takes more cloud compute than
Protocol Bots, which send HTTP requests without a browser.

The 4× multiplier is there because real browsers cost more to run, not because we think they are four
times more valuable. Protocol Bots are the economical choice for APIs and high-volume HTTP traffic.
Browser Bots and Playwright scripts are the better fit when you need real browser load testing: JavaScript,
page resources, and front-end timing.

You can mix them. A typical pattern is Browser Bots or Playwright scripts on the important user flows,
with Protocol Bots adding background traffic.

## How free Loadster Fuel works

Signing up gives you 50 units of fuel. That is enough for a handful of tests, such as 100 Protocol Bots
for 30 minutes. No credit card, no commitment.

When the 50 units run out, you can [subscribe to a monthly fuel plan](https://loadster.com/pricing/) or buy pay-as-you-go fuel.
Until then, you can still edit scripts, save scenarios, and look at reports. Running out of fuel pauses
new load tests and fuel-based monitor cycles; it does not delete your data.

The 50 free units are a starter amount, not a monthly allowance. They do not refill on their own.

## Monthly Fuel Plans versus pay-as-you-go fuel

[Monthly Fuel Plans](https://loadster.com/pricing/) start at $77/month for 1,000 units. Unused plan fuel rolls over as long
as you keep the subscription, and the per-unit price is lower than pay-as-you-go.

[Pay-as-you-go fuel](https://loadster.com/pricing/) starts at $97 for 1,000 units. There is no subscription, and that fuel
never expires.

If you have both, plan fuel is used first, then pay-as-you-go. Some teams keep a monthly plan for routine
tests and buy extra fuel for the occasional big run.

## Estimated versus actual Loadster Fuel usage

The dashboard estimates fuel from the bots, bot types, and durations in your scenario. Actual usage is
based on how long the bots really ran, which can be a bit more or less than the estimate.

If a test overruns because bots finish a long iteration after time is up, it can burn extra fuel. If you
stop a test early, it burns less. See
[estimated and actual fuel usage](https://loadster.com/faqs/estimated-and-actual-fuel-usage/) for the usual reasons.