# What is a PRIME estimate?

If several estimates for a species have been published or communicated, then one PRIME estimate has been identified as the estimate preferred to any other for that species.

### Searching for *Prime estimates*

Using this search option will return just the prime estimate for each species if more than one C-value estimate is available.

### Searching for *All estimates*

Using this option will return all available C-value estimates for a species. The prime estimate of the species is identified in the 'Prime' column on the Results page.