Declyn is a rare variant of Declan that peaked in 2018 and has grown less common since.
Declyn is predominantly a boy name. In 2025 it ranked #4,575 among boys (22) and #6,607 among girls (17) — overall #6,650 across all names. The charts below show girls and boys separately.
| Year | U.S. births | U.S. + territories | ♀ Rank | ♂ Rank |
|---|---|---|---|---|
| 2025 | 39 | 39 | #6,607 | #4,575 |
| 2024 | 39 | 39 | #5,999 | #5,110 |
| 2023 | 46 | 46 | #6,483 | #3,915 |
| 2022 | 53 | 53 | #6,276 | #3,426 |
| 2021 | 64 | 64 | #5,125 | #3,087 |
| 2020 | 59 | 59 | #4,572 | #3,593 |
| 2019 | 44 | 44 | #7,113 | #3,821 |
| 2018 | 70 | 70 | #4,589 | #2,959 |
| 2017 | 54 | 54 | #5,410 | #3,606 |
| 2016 | 61 | 61 | #6,236 | #2,896 |
| 2015 | 54 | 54 | #5,705 | #3,534 |
| 2014 | 51 | 51 | #6,041 | #3,552 |
| 2013 | 36 | 36 | #11,249 | #3,774 |
| 2012 | 34 | 34 | #7,545 | #5,082 |
| 2011 | 28 | 28 | #11,433 | #4,856 |
| 2010 | 12 | 12 | — | #6,776 |
| 2009 | 13 | 13 | #15,734 | #10,109 |
| 2007 | 6 | 6 | — | #11,257 |
| 2004 | 5 | 5 | #16,779 | — |