Convert US fluid ounce to UK gallon
Unit definitions
US fluid ounce
$\frac{1}{128}$ of a US liquid gallon is a US fluid ounce.
UK gallon
The UK gallon is a unit of volume equal to exactly $4.546\,09$ liters.
How to convert US fluid ounce to UK gallon
$$\text{Volume}_{\text{gal (uk)}} = \text{Volume}_{\text{oz (us)}} \cdot 0.006505267067413975526221434243492760$$
Examples
Example 1
Convert $40.0\ \text{oz (us)}$ to $\text{gal (uk)}$.
$$\text{Volume}_{\text{gal (uk)}} = 40.0 \cdot 0.006505267067413975526221434243492760$$
$$\text{Volume}_{\text{gal (uk)}} = 0.260211$$
$$\therefore \ 40.0\ \text{oz (us)} = 0.260211 \ \text{gal (uk)}$$
Example 2
Convert $90.0\ \text{oz (us)}$ to $\text{gal (uk)}$.
$$\text{Volume}_{\text{gal (uk)}} = 90.0 \cdot 0.006505267067413975526221434243492760$$
$$\text{Volume}_{\text{gal (uk)}} = 0.585474$$
$$\therefore \ 90.0\ \text{oz (us)} = 0.585474 \ \text{gal (uk)}$$
Example 3
Convert $120.0\ \text{oz (us)}$ to $\text{gal (uk)}$.
$$\text{Volume}_{\text{gal (uk)}} = 120.0 \cdot 0.006505267067413975526221434243492760$$
$$\text{Volume}_{\text{gal (uk)}} = 0.780632$$
$$\therefore \ 120.0\ \text{oz (us)} = 0.780632 \ \text{gal (uk)}$$
Example 4
Convert $135.0\ \text{oz (us)}$ to $\text{gal (uk)}$.
$$\text{Volume}_{\text{gal (uk)}} = 135.0 \cdot 0.006505267067413975526221434243492760$$
$$\text{Volume}_{\text{gal (uk)}} = 0.878211$$
$$\therefore \ 135.0\ \text{oz (us)} = 0.878211 \ \text{gal (uk)}$$
Example 5
Convert $190.0\ \text{oz (us)}$ to $\text{gal (uk)}$.
$$\text{Volume}_{\text{gal (uk)}} = 190.0 \cdot 0.006505267067413975526221434243492760$$
$$\text{Volume}_{\text{gal (uk)}} = 1.236001$$
$$\therefore \ 190.0\ \text{oz (us)} = 1.236001 \ \text{gal (uk)}$$