Reserves

The Ripple Consensus Ledger applies reserve requirements, in XRP, to protect the shared global ledger from growing excessively large as the result of spam or malicious usage. The goal is to constrain the growth of the ledger to match Moore's Law so that a current commodity-level machine can always fit the current ledger in RAM and the full ledger history on disk.

Each account in the shared global ledger must hold a minimum of XRP in order to submit transactions, and it cannot send this XRP to other accounts. You cannot create a new account unless you send enough XRP to meet the minimum reserve requirement.

The current minimum reserve requirement is 20 XRP. (This is the cost of an account that owns no additional objects in the ledger.)

Base Reserve and Owner Reserve

The reserve requirement is divided into two parts:

  • The Base Reserve is a minimum amount of XRP that is required for every account in the ledger. Currently, this is 20 XRP (20000000 drops).
  • The Owner Reserve is an additional requirement that scales with the number of objects that the account owns in the ledger. Currently, this is 5 XRP (5000000 drops) per item.

Owner Reserves

Many objects in the ledger are owned by a particular account, and therefore count toward the reserve requirement of that account. When objects are removed from the ledger, they no longer count against their owner's reserve requirement.

  • Offers are owned by the account that placed them. An Offer can be automatically removed from the ledger if it is fully consumed or if it is found unfunded during transaction processing. Alternatively, the owner can cancel an offer by sending an OfferCancel transaction, or by sending an OfferCreate transaction that contains an OfferSequence parameter.
  • Trust lines are shared between two accounts. The owner reserve can apply to one or both of the accounts, depending on whether the fields that account controls are in their default state. See Contributing to the Owner Reserve for details.
  • Owner directories list all the ledger nodes that contribute to an account's owner reserve. However, the owner directory itself does not count towards the reserve.

Owner Reserve Edge Cases

The Ripple Consensus Ledger considers an OfferCreate transaction to be an explicit statement of willingness to hold an asset. Consuming the offer automatically creates a trust line (with limit 0, and a balance above that limit) for the taker_pays currency if such a trust line does not exist. However, if the offer's owner does not possess enough XRP to meet the additional reserve requirement of the new trust line, the offer is considered unfunded. See also: Lifecycle of an Offer.

Going Below the Reserve Requirement

During transaction processing, a transaction can only be successful if the sending account possesses at least the reserve requirement in XRP. In the process, the transaction cost destroys some of the sending account's XRP balance. This can cause an account to go below the reserve requirement.

When an account has less XRP than its current reserve requirement, it cannot send new transactions. Even so, it continues to exist in the ledger, as all accounts do. Unless the reserve requirements decrease, the only way for the account to become able to send transactions again is for it to receive enough XRP that it meets the reserve requirement.

Exception: When an account is below the reserve requirement, it can send new OfferCreate transactions to acquire more XRP, or other currencies on its existing trust lines. These transactions cannot create new trust lines, or Offer nodes in the ledger, so they can only execute trades that consume Offers that are already in the order books.

Changing the Reserve Requirements

The Ripple Consensus Ledger has a mechanism for changing the reserve requirements in order to account for long-term changes in the value of XRP. Any changes have to be approved by the consensus process. See Fee Voting for more information.