1-month SIM only deals UK Three / EE

Best 1-Month SIM-Only Deals in the UK: Options on Three & EE (2025)

Looking for a 30-day rolling SIM plan on Three or EE without committing to a long contract? Good news — there are solid flexible deals for both networks, whether you want tons of data or just the basics. I’ve researched and tested what’s actually available in 2025, including MVNO options, real-world trade-offs, and smart tips to get the most value.

Why Choose a 1-Month SIM-Only Plan?

Flexibility: Cancel or change your plan each month — no long-term tie-ins.
Try before you commit: Test a network (Three or EE) before locking into 12- or 24-month SIMs.
Budget control: Predictable monthly payments, and you won’t get stuck paying for data you don’t use.
Rolling usage: Ideal for seasonal use, short-term stays, or when you don’t need a permanent SIM plan.

Top 1-Month SIM Deals on the Three Network

Here are some of the most competitive and flexible 30-day SIM plans that use Three’s network:

Three’s Own 30-Day SIMs

Three offers its own 30-day SIM plans directly: :contentReference[oaicite:0]{index=0}

4 GB SIM: £19/month for 30 days, includes 5G, unlimited calls & texts. :contentReference[oaicite:1]{index=1}
12 GB SIM: £22/month, for more data-heavy users. :contentReference[oaicite:2]{index=2}
120 GB “Big Data” SIM: £24/month per USave’s listing. :contentReference[oaicite:3]{index=3}
Unlimited Data SIM: £30/month for full 5G and unlimited everything. :contentReference[oaicite:4]{index=4}

These plans come with Three’s 5G and access to the Three+ rewards app. :contentReference[oaicite:5]{index=5}

Third-Party 1-Month SIM Options on Three

There are several MVNOs that piggyback on Three’s network and offer great value for 30-day rolling plans:

Smarty: 12 GB for £6/month, or 18 GB for £7/month. :contentReference[oaicite:6]{index=6}
Pros: Very cheap, flexible; Cons: Not unlimited on the very low-cost plans.
iD Mobile: 60 GB 5G SIM for £8/month (1-month plan) — per 5G.co.uk listings. :contentReference[oaicite:7]{index=7}
Pros: Huge data, good for hotspot or heavy data use; Cons: Might be overkill if you don’t use that much.
Honest Mobile: According to Ken’s Tech Tips, they offer a 1-month unlimited data deal on Three’s network for £25/month. :contentReference[oaicite:8]{index=8}
Pros: True unlimited, eco-friendly brand; Cons: Higher cost, data prioritisation might apply.

Popular 1-Month SIM Deals on the EE Network

While EE’s own 30-day SIM-only deals are less common than Three’s, there are a few good options — especially through MVNOs or eSIM deals.

KenTechTips eSIM deal: 25 GB SIM-only on EE eSIM for £25/month. :contentReference[oaicite:9]{index=9}
Pros: Works without physical SIM, good data allowance; Cons: Might require eSIM-compatible device.
Lyca Mobile (on EE): According to 5G.co.uk, Lyca has a 1-month rolling plan with 150 GB 5G data for ~£10 (promotional). :contentReference[oaicite:10]{index=10}
Pros: Massive data for the price; Cons: Promo may change, and very high usage could be deprioritised.

What to Watch for When Choosing a 1-Month SIM Plan

1. Check Fair-Use and Speed Caps

Some “unlimited” 1-month SIMs may slow down your data after heavy use or during peak times. Always read the fine print or ask for the “fair-use policy”.

2. Roaming Conditions

Three’s 30-day SIMs include roaming to many destinations. :contentReference[oaicite:11]{index=11} If you're travelling, check whether your 1-month SIM plan includes roaming and under what terms.

3. Network Coverage

Speed and reliability depend a lot on where you live or work. Test coverage with a 1-month plan before switching long term — especially for 5G.

4. Renewal & Cancellation

With a 30-day SIM, your plan rolls over every month. Make sure you know how to cancel or change it before the next billing cycle. Three’s policy: you need to give 30 days’ notice. :contentReference[oaicite:12]{index=12}

5. Extras & Add-Ons

On Three’s 30-day SIM, you can add extras like more data or Paramount+ via their “add-on” offers. :contentReference[oaicite:13]{index=13}

Who Should Consider These 1-Month SIM Options?

Short-term residents or visitors: If you're in the UK for only a few months, the 30-day SIM makes a lot of sense.
Flex users: If you hate long contracts and want to switch plans or networks easily.
Data testers: Perfect if you’re testing how much data you actually need — you’re not locked in.
Budget-conscious: Rolling SIMs from MVNOs (like Smarty or iD) can be much cheaper than traditional plans.

Potential Drawbacks

Higher monthly rate: Short-term plans often cost more per GB than long-term SIM-only deals.
No commitment perks: You might miss out on discounts or benefits that come with 12- or 24-month contracts.
Monthly renewal risk: If you forget to cancel, the plan rolls again for another month.

Final Thoughts

1-month (30-day) SIM-only deals on both Three and EE give excellent flexibility for modern users — whether you’re just testing a new network, staying temporarily in the UK, or simply don’t want to be tied into a long contract. For maximum value, Three’s own 30-day SIMs are hard to beat. But if you’re chasing bigger data allowances on rolling contracts, MVNOs like Smarty, iD, and Lyca offer strong alternatives. Test the coverage, read the small print, and pick the plan that aligns with how you actually use your phone — you’ll likely save money without giving up performance.