Micro-Investing Apps That Grow Your Spare Change

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Spare change adds up faster than most people expect. Micro-investing apps round up your card purchases or move small, regular amounts into the market for you.

The catch is the cost. A flat monthly fee can eat a big share of a small balance, so the math matters more than the marketing.

Quick answer: Acorns is the most direct spare-change app: it rounds up purchases and invests them once they reach $5, with plans at $4, $8 or $12 a month as of September 2026. Stash costs $12 a month and pairs investing with a debit card that rewards you in stock. Public has $0 commissions and no required subscription, but it has no round-up feature; you invest set amounts instead. On a balance of a few hundred dollars, a monthly fee can take a large share of it every year.

Updated on September 23, 2026 · Sources: Acorns, Stash, Public

Key takeaways

Round-ups invest the difference between a purchase and the next whole dollar.
A $4 monthly fee is $48 a year, or 4.8% of a $1,000 balance.
Subscriptions make more sense once your balance, or the perks you use, grow.
All three accounts hold investments that can lose value.

Micro-investing apps at a glance

App	Best for	Key numbers
Acorns	Automatic spare-change investing	$4, $8 or $12 a month
Stash	Investing plus stock rewards card	$12 a month · 3% IRA match
Public	Set amounts with no subscription	$0 commissions · 1% IRA match

Fees as of September 2026, from each provider’s official page.

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What a monthly fee really costs

Here is a quick way to see the fee’s weight. Multiply the monthly fee by 12, then divide by your balance.

Balance	$4 a month ($48 a year)	$12 a month ($144 a year)
$500	9.6% a year	28.8% a year
$2,000	2.4% a year	7.2% a year
$10,000	0.48% a year	1.44% a year

Fees work against compounding. The SEC’s Investor.gov explains how fees and expenses reduce your portfolio over time.

1. Acorns

The app that made round-ups popular. It invests your spare change in ready-made ETF portfolios.

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At a glance

Plans: Bronze $4 a month, Silver $8 a month, Gold $12 a month.
Round-Ups: a $2.50 purchase adds $0.50; Acorns invests the change once it reaches at least $5.
IRA match: 1% on new contributions in the first year with Silver; 3% with Gold.
Gold extras: an investment account for kids and the option to add individual stocks and ETFs.

Pros and cons

Fully automatic once your card is linked.
Checking, IRA and investing in one app.
The fee is heavy on small balances.
Round-ups alone grow slowly; recurring deposits do most of the work.

How to sign up

Download the app, pick a plan, answer a few questions and link the cards you want to round up.

2. Stash

A single-plan app that mixes investing, banking and a debit card that pays rewards in stock.

At a glance

Price: $12 a month, or $108 billed annually.
Extra advisory fee: 0.25% a year on Smart Portfolios with $1,000 or more and on managed retirement accounts.
Fractional shares: invest with $5 or less in thousands of stocks and ETFs.
Stock-Back card: up to 3% back in stock at bonus merchants; all rewards share a $10 monthly cap, then 0.125%.
Retirement match: 3% on eligible monthly net contributions, worth up to $225 a year.

Pros and cons

Rewards everyday spending with stock.
Annual billing saves 25%.
Highest fixed fee of the three.
Match rewards carry an early removal fee; read the terms.

How to sign up

Create an account in the app, complete the questionnaire and open the bank account that comes with the plan.

3. Public

A commission-free broker with no required subscription. It works well for small, scheduled deposits.

At a glance

Trading cost: $0 commissions on US-listed stocks and ETFs, in regular and extended hours.
Fractional shares: invest in stocks with any dollar amount.
Investment Plans: automatic recurring buys of up to 20 stocks, ETFs or crypto. Crypto buys in a Plan carry a 1.25% fee.
Watch out for: a $3.99 monthly inactivity fee on accounts under $70 with no activity for 6 months, and $100 to transfer the account out.

Pros and cons

No monthly fee to invest.
1% match on IRA contributions.
No automatic round-ups.
Fractional shares can’t be transferred to another broker.

How to sign up

Open a brokerage account online, fund it by bank transfer and set up an Investment Plan.

How to choose

Choose Acorns if you want spare change invested without thinking about it.
Choose Stash if you will use its debit card and retirement match enough to cover $12 a month.
Choose Public if you can commit to a small automatic deposit and want to avoid a subscription.

Want more choice? Our list of investment apps and brokerages for beginners compares larger platforms with $0 minimums.

Protection and limits

SIPC protects securities and cash at a failed member brokerage up to $500,000, including $250,000 cash, but not market losses.
IRA matches count only on contributions within the IRS limit of $7,500 for 2026, or your taxable compensation if less.

Before you start

Pay off high-interest card debt first; see how to use a credit card without paying interest.
Keep an emergency fund outside the app.
Work out the fee as a percentage of your balance.
Add a recurring deposit, even $5 a week.
Review the plan once a year and downgrade if you don’t use the perks.

Round-ups work best alongside a budget. Our guide to budgeting apps that help you stop living paycheck to paycheck can free up more to invest.

How we compared these apps

Checked: every fee on September 23, 2026, on each provider’s official pricing page or fee schedule.
Order: not a ranking. Apps appear from most to least automated; our top pick for spare-change investing is in the Quick answer.
Criteria: monthly fees, advisory fees, round-up features, minimums and account extras.
Scope: US apps for US residents.
Independence: no provider paid for placement.

Not financial advice. Investing involves risk, including loss of principal. Fees and terms checked on September 23, 2026 with each provider’s official page; confirm before opening an account.

FAQ

Are micro-investing apps worth it?

They can be, if the fee is small relative to your balance and the app gets you investing regularly. On a very small balance, a flat monthly fee takes a large bite.

How do round-ups work?

The app tracks your linked card purchases and rounds each one up to the next dollar. The difference is invested, often once it reaches a set amount, such as $5 at Acorns.

Can I lose money with a micro-investing app?

Yes. The money is invested in stocks and ETFs, which can fall in value.

Which app has no monthly fee?

Of these three, Public has no required subscription for investing. Watch its inactivity and transfer-out fees.

Can I cancel a subscription later?

Stash says you can cancel at any time. Before canceling any plan, check what happens to your invested balance and any match you received.

For the full picture, see our hub How to Start Investing 2026 (US), our guide on how to start investing with just $100 and Roth IRA limits for 2026 and how they compare with a 401(k).

Sources

Ieveera SEO is an independent publisher, not a bank or financial advisor; content is for information only and may include paid affiliate links that never affect our rankings — always confirm current rates and terms with the provider. Investing involves risk, including loss of principal. Not investment advice.