The floorplan code is on the decal by your door or in your owner's paperwork.
Sold 2023 and later
40DUPLEX60 × 80 in + 32 × 74 in / 54 × 74 in bunks2024–2025 · Sierra Destination
399LOFT44 × 74 in bunks2020–2025 · Sierra Destination
403RD60 × 80 in2020–2025 · Sierra Destination
420FL60 × 80 in2023–2025 · Sierra Destination
3550BH72 × 80 in2024–2025 · Sierra
3710HBFB66 × 80 in2026 · Sierra
3880BH72 × 80 in + 54 × 74 in bunks2025 · Sierra
3900HBLR72 × 80 in2025–2026 · Sierra
3990FL72 × 80 in + 44 × 74 in bunks2024–2026 · Sierra
4002FB60 × 80 in + 32 × 74 in bunks2024–2026 · Sierra
4003MB72 × 80 in2024–2026 · SierraOlder floorplans
Sierra mattress sizes by floorplan
| Floorplan | Year | Main bed | Bunks | Source |
|---|---|---|---|---|
| 40DUPLEX | 2025 | 60 × 80 in | 32 × 74 in, 54 × 74 in | Forest River spec sheet |
| 399LOFT | 2023 | – | 44 × 74 in | Forest River spec sheet |
| 403RD | 2023 | 60 × 80 in | – | Forest River spec sheet |
| 420FL | 2023 | 60 × 80 in | – | Forest River spec sheet |
| 3550BH | 2025 | 72 × 80 in | – | Forest River spec sheet |
| 3710HBFB | 2026 | 66 × 80 in | – | Forest River spec sheet |
| 3880BH | 2025 | 72 × 80 in | 54 × 74 in | Forest River spec sheet |
| 3900HBLR | 2025 | 72 × 80 in | – | Forest River spec sheet |
| 3990FL | 2025 | 72 × 80 in | 44 × 74 in | Forest River spec sheet |
| 4002FB | 2026 | 60 × 80 in | 32 × 74 in | Forest River spec sheet |
| 4003MB | 2025 | 72 × 80 in | – | Forest River spec sheet |
| 372LOK | 2021 | 72 × 80 in | – | Forest River spec sheet |
| 404QBWD | 2020 | 32 × 74 in | – | Forest River spec sheet |
The newest year with a published size is shown. Each floorplan page lists every year.