I ran Plum and Chip simultaneously for six weeks on the same Starling current account. Same salary going in on the same date, same spending habits, both apps given full open banking permission to read transactions and pull money whenever their algorithm decided I had a surplus. This is a real Plum vs Chip test — not a marketing feature list.
The headline: Chip moved slightly more money overall. But Plum handled a difficult month considerably better. Here's what the data actually showed.
How Do Plum and Chip Decide When to Save?
Plum uses a rolling 30-day look-back window to assess your income, fixed outgoings, and spending patterns before deciding how much to pull. Chip's algorithm is more reactive — it appears to use a shorter 7–14 day window, which makes it quicker to respond to a good week but also more likely to pull at awkward moments.
AI savings algorithm: software that reads your bank transaction history and automatically transfers a calculated surplus to a savings pot — no manual input required, no rule-setting, just open banking access and a model that learns your patterns over time.
Both apps show a predicted next-save figure in the home screen, but neither tells you exactly when the transfer will land. That matters more than you'd think if you're running a salary-day automation stack — I covered the timing problem in detail in my post on coordinating standing orders so a £2,500 bills week doesn't touch your spending money. Same issue, different context.
The Standing Order Test: What Happened When £850 Left Early?
Plum detected the large early debit and paused saving for six days. Chip pulled £28 three days later, which triggered a returned payment and a £12 fee. That single difference tells you most of what you need to know about how these two algorithms are calibrated.
My council tax standing order normally processes on the 5th. February's 5th fell on a bank holiday, so it processed on the 2nd instead — £850 out at 6am. Both apps were watching the same account.
By that evening, Plum had flagged the debit and queued a zero-save for the next cycle. No pull. It essentially sat out the week, then resumed normally the following Monday. Honestly, I was impressed. It read the situation correctly without me doing anything.
Chip showed no such flag. On the 5th — three days after the standing order — it pulled £28. Technically the account had a positive balance. But I had a mobile direct debit due that same afternoon. Chip got there first. The phone payment bounced. £12 returned payment charge from the provider, a stern letter, and a Tuesday morning ruined before I'd even had my coffee. A bit rubbish, frankly.
To be fair to Chip: this is an edge case. A bank holiday shifting a large payment by three days is unusual. In all five other weeks of the test, Chip's pulls were fine. But the look-back window clearly doesn't catch the pattern of two large outgoings landing unusually close together — and that gap matters in real life.
Six Weeks of Deposits — The Actual Numbers
Over six weeks, Plum saved £122 and Chip saved £114. The eight-pound difference is almost irrelevant — what's more interesting is the week-by-week rhythm each app chose.
| Week | Plum | Chip |
|---|---|---|
| Week 1 | £18 | £22 |
| Week 2 | £31 | £19 |
| Week 3 | £27 | £28 |
| Week 4 (standing order week) | £0 — paused | £28 — caused returned payment |
| Week 5 | £24 | £0 — over-corrected, paused |
| Week 6 | £22 | £17 |
| Total | £122 | £114 |
Week 4 is the story. Chip pulled aggressively in the wrong week, then over-corrected and sat out Week 5 entirely. The net result: in the month that actually tested both apps, Chip saved £28 (at a £12 cost) and Plum saved £24 (correctly, without incident). Plum won that month on every metric that matters.
Interest Rates, Fees, and What You Actually Earn
Chip currently pays around 4.84% AER on its easy-access savings account, versus Plum's 4.45% on its equivalent standard tier — a meaningful gap if you're letting the balance compound rather than dipping in regularly.
Both apps have free and paid tiers. Plum Pro runs at £2.99/month and unlocks higher interest pots and investment features. Chip's paid tier is similarly priced. I ran both on free plans for the full six weeks — I wanted to test what real people who aren't paying a monthly subscription fee actually get. On free plans, Chip restricts withdrawal frequency (fine if you're a set-and-forget saver, irritating if you use it as a buffer). Plum's free tier is genuinely functional for basic automated saving.
If you're building a layered automated savings stack — salary sorter on Monzo routing bills to pots, round-ups going somewhere else, and an AI saver on top for the remaining surplus — Chip's higher rate makes it the better long-term holding account. But only if your cash flow is predictable enough that the algorithm won't misfire.
Plum vs Chip: Which Should You Actually Use?
Use Plum if your cash flow is lumpy, variable, or involves irregular large outgoings — freelancers, anyone with shifted direct debits, people with council tax lump sums or irregular standing orders. Its caution is usually the right call. Use Chip if your income and outgoings land on exactly the same date every month and you want slightly better interest on what accumulates.
And running both isn't as daft as it sounds. Over six weeks I saved £236 total — money that would have sat in the Starling current account doing nothing. The combined weekly pull averaged around £39, which is lower than either app would have attempted alone (each only sees a partial surplus once the other has already pulled). But the pausing behaviour balanced out nicely: when Plum paused, Chip sometimes still pulled. When Chip over-corrected, Plum kept going.
The one feature I'd add to Chip tomorrow: a large-outgoing-detected pause mode. Plum has it. It's not glamorous, but it's the difference between a smooth month and an unexpected fee letter. Small detail, real cost.
For getting the most out of either app, the key is making sure your salary-day routing is sorted before you add an AI saver on top. My post on Monzo Salary Sorter vs Starling Saving Spaces goes into exactly how to sequence payday automations so pulls from apps like Plum and Chip don't compete with your bills pot.
Both are worth having. Neither is perfect. Plum is safer; Chip pays more. Pick based on how boring your monthly cash flow is.
Free tool: Use our Subscription & Direct Debit Audit spreadsheet (free) to find out exactly where your money goes each month. See all our UK finance tools.
Both apps have free tiers — try Plum or Chip with your own account and see which algorithm fits your spending pattern. It costs nothing to find out.