Cheap Prepaid Mobile Plans Under $20
In our database, we're comparing 29 prepaid mobile plans priced at $20 a month or less from 15 providers across the Telstra, Optus and TPG networks (TPG's network also covers Vodafone-branded plans). Prices in this list run from $1.00 to $20 a month, averaging $12.91, with data allowances from a no-data pay-as-you-go plan up to unlimited data. Not every plan on this list stays under $20 for long, though -- 8 of the 29 are genuinely $20-or-under with no price increase, while the other 21 only start below $20 as a limited-time promo and revert to a higher regular price afterwards, in some cases by more than 20 times the starting price. We've split the tables below so you can tell the difference at a glance.
(Yomojo, promo)
(ALDI mobile)
Genuinely $20-or-under, no price hike (8 plans)
Sorted by cost per GB (regular price), lowest first. These plans cost the same now as they will on renewal -- what you see is what you keep paying.
| Provider | Plan | Network | Data | Talk & Text | Price | Cost / GB | |
|---|---|---|---|---|---|---|---|
| Kogan Mobile | Small Prepaid SIM Only Mobile Plan | TPG | 20GB (4G) | Unlimited | $10.00 / 30 days | $0.50 | View Plan |
| Vodafone | $13 Prepaid Plus Starter Pack | TPG | 6GB (4G,5G) | Unlimited | $5.00 / 7 days | $0.83 | View Plan |
| amaysim | 7 Day SIM Only Prepaid Mobile Plan | Optus | 10GB (4G,5G) | Unlimited | $10.00 / 7 days | $1.00 | View Plan |
| Telstra | $15 Pre-Paid SIM Only Weekly Plan | Telstra | 6GB (4G,5G) | Unlimited | $10.00 / 7 days | $1.67 | View Plan |
| Boost Mobile | 7 Day Expiry - ESIM Only | Telstra | 8GB (4G,5G) | Unlimited | $14.00 / 7 days | $1.75 | View Plan |
| OCCOM | Nano | TPG | 10GB (4G) | Unlimited | $18.00 / 30 days | $1.80 | View Plan |
| Optus | Flex Plus - Weekly | Optus | 5GB (4G,5G) | Unlimited | $13.00 / 7 days | $2.60 | View Plan |
| ALDI mobile | $2 Pay As You Go Prepaid Mobile Plan | Telstra | Pay as you go | N/A | $2.00 / 365 days | N/A | View Plan |
Starts under $20, price increases later (21 plans)
Sorted by current advertised price, lowest first. "Now" is the price you'll pay today; "Then" is the regular price it reverts to once the promo period ends.
| Provider | Plan | Network | Data | Talk & Text | Now | Then (regular) | |
|---|---|---|---|---|---|---|---|
| Yomojo | Starter Prepaid | Optus | 29GB (4G) | Unlimited | $1.00 | $24.00 | View Plan |
| amaysim | 30GB Data Only Prepaid Mobile Plan | Optus | 30GB (4G) | N/A | $10.00 | $25.00 | View Plan |
| amaysim | 15GB Unlimited Small SIM Only Plan | Optus | 15GB (4G,5G) | Unlimited | $11.00 | $30.00 | View Plan |
| Lebara Mobile | $30 SIM Plan | TPG | 70GB (4G,5G) | Unlimited | $11.00 | $30.00 | View Plan |
| Boost Mobile | $39 Prepaid Plan | Telstra | 80GB (4G,5G) | Unlimited | $12.00 | $39.00 | View Plan |
| Kogan Mobile | Medium Prepaid SIM Only Mobile Plan | TPG | 60GB (4G) | Unlimited | $12.00 | $25.00 | View Plan |
| felix | 25GB SIM-only Mobile Plan | TPG | 25GB (4G,5G) | Unlimited | $12.50 | $25.00 | View Plan |
| iiNet | Small Plan | TPG | 25GB (4G) | Unlimited | $12.50 | $25.00 | View Plan |
| TPG | Small SIM Only Mobile Plan | TPG | 25GB (4G) | Unlimited | $12.50 | $25.00 | View Plan |
| Optus | Flex Plus - 30GB Data | Optus | 50GB (4G,5G) | Unlimited | $14.00 | $40.00 | View Plan |
| Vodafone | $40 Prepaid Plus Starter Pack | TPG | 90GB (4G,5G) | Unlimited | $14.00 | $40.00 | View Plan |
| felix | 50GB SIM-only Mobile Plan | TPG | 50GB (4G,5G) | Unlimited | $15.00 | $30.00 | View Plan |
| Lebara Mobile | $40 SIM Plan | TPG | 140GB (4G,5G) | Unlimited | $15.00 | $40.00 | View Plan |
| Lycamobile | S | TPG | 80GB (4G,5G) | Unlimited | $15.00 | $30.00 | View Plan |
| Telsim | $49.90 Prepaid Plan | Telstra | 80GB (4G,5G) | Unlimited | $15.00 | $49.90 | View Plan |
| Optus | Flex Plus - 35GB Data | Optus | 65GB (4G,5G) | Unlimited | $17.00 | $49.00 | View Plan |
| iiNet | Medium Plan | TPG | 50GB (4G,5G) | Unlimited | $17.50 | $35.00 | View Plan |
| TPG | Medium SIM Only Mobile Plan | TPG | 50GB (4G,5G) | Unlimited | $17.50 | $35.00 | View Plan |
| amaysim | 100GB Data Only Prepaid Mobile Plan | Optus | 100GB (4G,5G) | N/A | $18.00 | $50.00 | View Plan |
| felix | Unlimited Data SIM-only Mobile Plan | TPG | Unlimited (4G,5G) | Unlimited | $20.00 | $40.00 | View Plan |
| Lycamobile | M | TPG | 120GB (4G,5G) | Unlimited | $20.00 | $40.00 | View Plan |
Compare by network
Genuinely $20-or-under, by network speed
Only the 8 plans that stay $20-or-under long-term (no promo price hike) are included here, split by whether the network supports 5G or is 4G-only.
5G-capable (5 plans)
4G (2 plans)
ALDI mobile's $2 Pay As You Go Prepaid Mobile Plan ($2.00 / 365 days, Telstra network) isn't shown above -- it includes no data or talk allowance, and our data source doesn't specify a network speed for it.
Frequently asked questions
Prices and data allowances shown are current in our database as of August 2026 and reflect advertised carrier pricing at time of listing. Where a plan has an introductory promo, we show both the current and regular price so you can see the true long-term cost. Plans, prices and inclusions change frequently, and details are entered into our database manually so errors are possible -- we do not guarantee the accuracy of any price, allowance, or other detail shown. Always confirm the final price and all plan information directly with the carrier before signing up.