The math
Roblox keeps a 30% Marketplace Fee on game passes and developer products and you receive 70%, rounded down to a whole Robux: floor(100 × 7 ÷ 10) = 70.
Working backwards? See 100 Robux with tax. To receive 100 you would list at 143.
Nearby amounts
Both directions, using the same rounding as Roblox.
| Amount | List at this, you get | To get this, list at |
|---|---|---|
| 50 | 35 | 72 |
| 75 | 52 | 108 |
| 90 | 63 | 129 |
| 100 | 70 | 143 |
| 110 | 77 | 158 |
| 125 | 87 | 179 |
| 150 | 105 | 215 |
| 200 | 140 | 286 |
Robux transfer version
As a Robux transfer (10 to 500 per transfer) the recipient gets 90 and the game gets 10. Roblox does not document rounding for odd amounts, so this rounds down.