Is $30 a day possible?

Yes, but it is grueling. You would be eating only street food, taking local buses instead of tourist minivans, and sleeping in the cheapest hostels with no AC.

Do I need to carry cash?

Yes. While urban areas accept cards, you will need cash for night markets, rural transport, and small guesthouses. Always carry at least $100 USD in clean, crisp bills as an emergency reserve.

How to create a realistic backpacking budget for Southeast Asia

Budget for $40–$50 USD per day if you want a comfortable experience that includes hostels, street food, and occasional excursions. This daily amount covers your accommodation, food, local transport, and a moderate allowance for beer or activities.

Calculate your fixed daily burn rate. Dorm beds typically cost $8–$15 per night. Expect to spend $15–$20 on food and water, and $10 on local transport (taxis, motorbikes, buses) and misc expenses. Sum these to get your 'floor' budget.
Add an 'activity buffer'. Set aside an extra $10 per day for 'big ticket' items like PADI scuba courses, Angkor Wat passes, or Ha Long Bay cruises. Don't spend it daily; let it accumulate for these specific expenses.
Account for regional price variance. Vietnam, Laos, and Northern Thailand are cheaper ($35/day); Singapore and Southern Thailand islands are significantly more expensive ($70+/day). Weight your total budget toward your time spent in the pricier locations.
Factor in cross-border logistics. Budget $150 USD specifically for visas (e.g., Vietnam $25, Cambodia $30, Laos $40). These are one-time costs that aren't included in your daily spending.

Is $30 a day possible?: Yes, but it is grueling. You would be eating only street food, taking local buses instead of tourist minivans, and sleeping in the cheapest hostels with no AC.
Do I need to carry cash?: Yes. While urban areas accept cards, you will need cash for night markets, rural transport, and small guesthouses. Always carry at least $100 USD in clean, crisp bills as an emergency reserve.