For 'would', use 'baswn i' (I would), 'baset ti', 'basai fe/hi' plus 'yn'/''n' plus the verb-noun; 'byddwn i' is the more formal equivalent. For the 'if' half, use 'petai' plus the person: 'petai gen i amser' (if I had time), never the ordinary word 'os' with a conditional.
Examples
- Baswn i'n hoffi teithio mwy yn y dyfodol.
- I would like to travel more in the future.
- Petai gen i fwy o amser, baswn i'n dysgu offeryn.
- If I had more time, I would learn an instrument.
- Basai hi'n well petaen ni'n siarad yn onest.
- It would be better if we spoke honestly.
The mistake to avoid
Saying 'os baswn i' — hypothetical 'if' is 'petawn i / petai', while 'os' is for real, likely conditions.
Where this fits in
Myfyrio ar fywyd, Welsh B2: Reflect on life, values, personal growth, and relationships.