---
eip: 3198
title: BASEFEE opcode
author: Abdelhamid Bakhta (@abdelhamidbakhta), Vitalik Buterin (@vbuterin)
discussions-to: https://ethereum-magicians.org/t/eip-3198-basefeeopcode/5162
status: Draft
type: Standards Track
category: Core
created: 2021-01-13
requires: 1559
---

## Simple Summary
Add a `BASEFEE (0x48)` that returns the value of the base fee of the current block it is executing in.

## Abstract


## Motivation
The intended use case would be for contracts to get the value of the base fee. This feature would enable or improve existing use cases, such as:
- Contracts that need to set bounties for anyone to "poke" them with a transaction could set the bounty to be `BASEFEE + x`, or `BASEFEE * (1 + x)`. This makes the mechanism more reliable, because they will always pay "enough" regardless of market conditions.
- Gas futures can be implemented based on it. This would be more precise than gastokens.
- Improve the security for state channels, plasma, optirolls and other fraud proof driven solutions. Having the `BASEFEE` as an input allows you to lengthen the challenge period automatically if you see that the `BASEFEE` is high.

## Specification
Add a `BASEFEE` opcode at `(0x48)`, with gas cost `G_base`.

|  Op  	| Input 	| Output 	| Cost 	|
|:----:	|:-----:	|:------:	|:----:	|
| 0x48 	|   0   	|    1   	|   2  	|

## Rationale

## Backwards Compatibility
This EIP is backwards-compatible.

## Test Cases

### Nominal case
Assuming current block base fee is `7 wei`.
This should push the value `7` (left padded byte32) to the stack.

Bytecode: `0x4800` (`BASEFEE, STOP`)

|  Pc   |      Op     | Cost |   Stack   |   RStack  |
|-------|-------------|------|-----------|-----------|
|    0  |    BASEFEE  |    2 |        [] |        [] |
|    1  |    STOP     |    0 |       [7] |        [] |

Output: 0x
Consumed gas: `2`

## Security Considerations

## Copyright
Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).