What Is the Sharpe Ratio? A Plain Guide for Crypto Traders

Two strategies both finish the year up 20%.

One got there slowly, with small ups and downs. The other swung wildly and nearly fell apart twice along the way. On a results page they look the same. They are not the same.

The Sharpe ratio is the most common way to tell them apart. This post covers what it is, how to work it out, what a "good" number looks like, and where it can fool you.

The idea in one line

The Sharpe ratio is return divided by bumpiness.

Sharpe ratio = average return ÷ how much the returns swing

"How much the returns swing" is the standard deviation, a measure of how far each day's (or week's) result usually lands from the average. More swing means a rougher ride.

So a high Sharpe means you got a lot of return for each unit of bumpiness. A low Sharpe means you took a rough ride for not much.

It's named after William Sharpe, who first described it in 1966. The classic version subtracts a "risk-free" rate (what you'd get from cash) from the return first. Many crypto tools skip that step or set it to zero. Either is fine, as long as you say which one you used and compare like with like.

A worked example

Take daily results for two strategies:

• Strategy A: average day +0.1%, daily swing 1%.
• Strategy B: average day +0.1%, daily swing 3%.

Same average return. Very different ride.

Daily Sharpe for A: 0.1 ÷ 1 = 0.10. For B: 0.1 ÷ 3 = 0.033.

People usually quote the yearly number. To turn a daily Sharpe into a yearly one, multiply by the square root of the number of trading days in a year. Crypto trades every day, so that's the square root of 365, about 19.1. (Stock markets often use 252.)

• A: 0.10 × 19.1 ≈ 1.9 per year
• B: 0.033 × 19.1 ≈ 0.64 per year

A gets the same return as B with a third of the bumpiness. That's what the higher Sharpe is telling you.

You can do this in a spreadsheet. Put daily returns in a column, use AVERAGE and STDEV on it, divide, then multiply by SQRT(365).

What counts as a good Sharpe?

Rough rules people use:

• Below 0: the strategy lost money over the period.
• Around 0.5 to 1: okay to decent.
• Above 1: good, if it holds up on new data.
• Above 2 or 3 in a backtest: be suspicious before you get excited.

That last point matters most. High backtest Sharpe ratios are easy to find by accident. If you try enough versions of an idea, one will look great by luck. We explain how to raise the bar for that in The Deflated Sharpe Ratio.

We ran a quick simulation

How much can a Sharpe ratio mislead on a short record? We made fake strategies with a known, fixed skill and measured them. Every result here is simulated on random data, not trading results.

Test 1: real skill, short record. 100 strategies, each built with a true yearly Sharpe of 1.0. Same skill, different luck.

• Over 90 days: 64 of 100 net positive (simulated). 30 of 100 showed a Sharpe below zero, and 27 of 100 showed a Sharpe above 2.
• Over 1 year: 73 of 100 net positive (simulated).
• Over 3 years: 89 of 100 net positive (simulated).

Same skill every time. On 90 days, the measured Sharpe was all over the place.

Test 2: no skill at all. 100 strategies with zero edge, 90 days each.

• 50 of 100 net positive (simulated), as you'd expect from coin flips.
• 34 of 100 showed a Sharpe above 1. None had any real edge.

The lesson: a Sharpe ratio from a few months of data is mostly noise. It needs a long record, and ideally new data, before it means much.

Where the Sharpe ratio misleads

1. It punishes good swings too. A big up day counts as "bumpiness" just like a big down day. Some traders use the Sortino ratio instead, which only counts the down swings.

2. It hides rare disasters. A strategy that wins small most days and loses big once in a while can show a high Sharpe right up until the bad day. Crypto has a lot of those days. Always look at the worst drawdown too. See What Is Maximum Drawdown?.

3. It depends on how you measure. Daily, weekly, per trade, with or without fees, with or without a risk-free rate. Two Sharpe ratios are only comparable if they were measured the same way.

4. It says nothing about how many things you tried. One Sharpe of 2.5 from your first test means more than one from your 500th.

How to use it honestly

• Include fees and slippage before you work it out. See How to Backtest Without Fooling Yourself.
• Report it with friends: number of trades, length of test, max drawdown, and expectancy. One number is never the whole story.
• Write down how many versions you tested.
• Check it on data the strategy has never seen, first out-of-sample, then forward in paper trading. See Backtest vs Forward Observation.

Where AI fits

AI tools like ChatGPT, Claude, Grok, or Cursor can work out a Sharpe ratio in seconds. When you ask, ask how it was measured: daily or per trade, which annualizing number, fees in or out, risk-free rate or not. If the tool can't tell you, the number isn't ready to trust.

How Pickled Lizard tests ideas like this

Pickled Lizard is an AI trading and research platform. You bring the idea, or your own AI does, and we test it the same way we test everything:

1. Backtest on the full data set we have, with fees and next-candle timing.
2. Paper forward testing on new market data, with real fees and timestamps. The idea shows as "still collecting" while it builds a record.
3. Verified only when its forward results reach 80% of its own backtest trade rate and 80% of its backtest win rate.

Results show on the public paper trading leaderboard. Pickled Lizard isn't an exchange and doesn't hold your money. It's a non-custodial aggregator that connects to your own exchange accounts. Our servers are in Europe. The beta is free, and live trading is off during the beta.

Want to see how your idea holds up on new data?

Test it free at pickledlizardz.com/join

Quick recap

• Sharpe ratio = average return ÷ how much returns swing. Higher means a smoother ride for the return.
• For crypto, turn a daily Sharpe into a yearly one by multiplying by about 19.1 (the square root of 365).
• Above 1 is good if it holds up on new data. Above 2 or 3 in a backtest deserves suspicion.
• In our simulation, 34 of 100 zero-edge strategies showed a Sharpe above 1 over 90 days (simulated). Short records are mostly noise.
• Always pair it with drawdown, trade count, and a forward test.

New here? Start with What Is a Quant Trading Strategy?.