Each-way arbitrage, or "each-way arbing", means backing an each-way bet at a bookmaker and laying its win and place legs separately on a betting exchange. It locks profit both ways only when the exchange place lay sits well below the bookmaker's place return. More often it's a positive-value play with variance, not the lock the name suggests.

Below: how the two-leg lay works, the maths that makes it a genuine arb, how to find one, and why you should only run it on gubbed accounts.

New to each-way matching? Start with our each-way matched betting guide, then come back here for the arb mechanic. This post assumes you already know the basics.

Summary#

• Each-way arbing means backing an each-way bet, then laying the win and place legs as two separate exchange bets.
• A true arb that locks both ways is rarer than the name implies. Most of the edge is positive expected value with variance, from extra places.
• It only works on big-field handicaps at longish odds. Short favourites have no gap to exploit.
• Size both legs in the each-way calculator and surface candidates in the each-way oddsmatcher.
• The load-bearing rule: only arb already-gubbed accounts. Repeated arbing flags healthy ones fast.
• The one number that matters is the gap between the bookmaker's place back and the exchange place lay. Check it before anything else.

What each-way arbitrage actually is#

An each-way bet is two stakes in one slip. Half goes on the horse winning, half on it finishing inside the bookmaker's place terms, with the place leg paid at a fraction of the win odds. That's the whole recap. If any of it feels new, the pillar covers it properly and there's no need to redraw it here.

To arb one, you lay both legs at the exchange. The win leg goes on the standard win market, the same lay bet you'd place on any qualifier. The place leg goes on the exchange place market, a separate book the exchange runs alongside it. Two lays, two lay stakes, two liabilities held upfront. If lay betting is still hazy, read that first.

There are two profit sources, and keeping them apart is the point of this post. The first is place-market inefficiency, which can lock value on every outcome. The second is extra places, which carry positive expected value with variance. The next two sections take each in turn.

True each-way arb vs extra-place value: the line nobody draws#

Here's the distinction the rest of the internet smears together.

A true each-way arb is a both-ways lock. It happens when the exchange place lay undercuts the bookmaker's place back by enough to leave you in front on the win branch and the place branch alike. Lay both legs at the right prices and you bank a small positive whether the horse wins, places or runs nowhere. It's real, but it's rare. Most days you won't find one.

The far more common case is extra-place value: positive expected value with variance. The exchange place market settles a fixed number of places that doesn't always match the bookmaker's promo terms. So the bookmaker might pay six places while the exchange "to be placed" market only covers five. That uncovered sixth place is pure upside. When the horse lands it, the bookmaker pays the place leg and neither lay loses, so you collect a big win. When it doesn't, you take a small, predictable loss. Across many bets the maths is positive. On any single bet it swings. That's variance, and it's the engine behind most extra-place offers.

So when a forum calls every each-way matched bet an "arb", treat it loosely. A true arb is a lock on this race; an extra-place play is a +EV bet you'd repeat a hundred times, knowing some of those hundred lose. Confusing the two is how people decide a losing run means something has broken.

The maths: when an each-way bet becomes a true arb#

There's exactly one comparison that decides it: the exchange place lay price versus the bookmaker place back return.

The bookmaker's place back is easy to compute. At 1/5 terms the place pays a fifth of the win, so:

place back decimal = (win fractional odds × 1/5) + 1

A 12/1 runner gives (12 × 1/5) + 1 = 2.4 + 1 = 3.4. If the exchange will let you lay the place at anything meaningfully below 3.4, the place leg makes money. That surplus can cover the small qualifying loss the win leg usually runs. Lay it at 3.4 or above and the place leg bleeds, so you're relying on extra places instead.

The intuition is cleaner in probabilities. A decimal price is just inverted implied probability: a place back of 3.4 implies a 1/3.4 ≈ 29% chance of placing. If the exchange thinks placing is more likely than that and prices its lay shorter, you've found a gap. If not, there's no gap and no arb.

The honest version: if the place lay isn't genuinely short of the place back, it's not an arb. It's a +EV bet with variance.

Worked example: spotting an each-way arb#

Take a 12/1 runner (13.0 decimal) in a 16-runner handicap, 1/5 terms, with the bookmaker paying 5 places. You stake £10 each-way, a £20 outlay. From the maths above the place back is 3.4.

Drop that into the each-way calculator: £10 each-way, win back 13.0, place back 3.4, your exchange commission, and the two lay prices. It sizes both legs at once and returns the per-outcome P/L. The figures below are representative; the calculator's live output is the proof, so trust the screenshot over any rounded number here.

First, the both-ways-positive case. Suppose the exchange place market lets you lay at around 3.0, comfortably below the 3.4 back. The calculator returns a win lay stake near £9 with a liability of roughly £108, plus a place lay stake near £11 with a liability around £22.

All three branches land positive. That's the true arb: a small lock whichever way the race falls.

Now take the more common case. Suppose the same race carries an extra-place promotion. The bookmaker pays six places while the exchange "to be placed" market still covers five, and the place lay sits at 3.6, above the 3.4 back. The standard five places no longer lock, so on most outcomes you take a small loss. The edge is the sixth place. When the horse lands it, the bookmaker pays the place leg with no offsetting lay, and you collect a large win. That's the +EV-with-variance case: it loses small, often, and wins big, rarely. Same calculator, same race, a completely different risk profile.

Where to find each-way arbs: odds, field size and place terms#

You don't hunt these by eye. Run the each-way oddsmatcher and let it rank candidate races by conversion, then sanity-check the gap yourself. The table below is the filter to apply before opening a calculator.

Field-size place thresholds aren't arbitrary; they follow the British Horseracing Authority's place-terms rules on handicaps and runner counts.

Here's where the maths-grad in me earns its keep. The exchange place market misprices the bookmaker's place terms most sharply on a big-field handicap, because nobody wants to lay 14/1 outsiders to place. I watched it last summer on a 20-runner 0-90 handicap at the York Ebor meeting. The place back was 3.4 on a 12/1 shot, and the exchange place lay sat near 3.0 for a full minute. Layers price the favourites and ignore the tail, and that neglected tail is the whole gap.

On the offer side, today's extra-place races shows which books pay more places than the exchange covers, and the bookmaker hub ranks the friendliest terms.

For higher-volume hunting, the pro extra-place matcher flags these races automatically. Useful once you're running this at scale, though it's not the place to start.

Why you should only arb gubbed accounts#

This is the rule competitors with a product to sell tend to skip.

Repeated each-way arbing is exactly the activity bookmaker trading teams watch for. Laying both legs, hammering extra places on outsiders, low margin, high frequency, almost no recreational behaviour mixed in. It's arb-shaped, and it flags a healthy account quickly. Spend a fresh, offer-eligible account on it and you'll lose the welcome and reload value, which is worth far more than the residual you squeeze from arbing.

The smart play inverts it. Run each-way arbing on accounts that are already gubbed. Once the bookmaker has stopped your offers, they've taken what they're going to take. They've trimmed your promotions, not your right to bet, so each-way arbing lets you extract residual value from a relationship that's otherwise dead. There's nothing left to protect.

Building accounts you want to keep healthy? Our guide to avoiding gubbings covers the behaviour that keeps you under the radar. Each-way arbing is the opposite, so do it deliberately, on accounts you've already written off.

The catch: variance, liquidity and the small print#

A few things the both-ways framing glosses over.

Variance. Extra-place +EV means losing runs are normal. A string of horses missing the extra place is a feature of the maths, not a sign you've done something wrong. Bankroll for the swings, not for the average.

Liquidity. The exchange place market on a small Saturday handicap can be £40 deep total. The price you size on may not be there when you click, and a chunky place lay will move it. Check the depth before placing, not after.

Settlement. Bookmaker and exchange place terms can diverge on dead-heats, Rule 4 deductions and non-runners. Read both sets of rules so a reduction doesn't quietly turn a lock into a loss.

It's still matched betting on the bookmaker side, so the profits stay tax-free in the UK. HMRC treats them as gambling winnings.

Frequently asked questions#

Is each-way arbing actually a sure thing?#

Not usually. A true each-way arb locks a small positive on every branch, but it only appears when the exchange place lay sits far enough below the bookmaker's place back. That isn't often. Most each-way arbing is positive expected value with variance: small losses on most runs, a large win when the horse lands an extra place. Profitable over volume, not certain on any single bet. The ASA's guidance on matched betting makes the same point: the technique still carries a real chance of losing money on any given bet.

What is the difference between each-way arbing and extra-place offers?#

Arbing is the mechanic: laying the win and place legs of an each-way bet separately at the exchange. The extra-place offer is the promotion that creates most of the edge, by paying more places than the exchange covers. You use the arbing mechanic to capture the extra-place value. One's the method, the other's the opportunity.

What odds and field size are best for each-way arbing?#

Roughly 6.0 and up (5/1 or longer) in handicaps of 16 or more runners on 1/5 terms. Big fields pay 4 to 5 places, and at longer odds the exchange tends to overprice the place lay. Short favourites don't work: the place lay tracks the place back too closely, so there's no gap.

Does each-way arbing get you gubbed?#

Yes, and quickly on a healthy account. It's low-margin, high-frequency, arb-shaped activity that trading teams flag. Run it only on accounts that are already restricted, where there's nothing left to protect.

Which calculator do I use for each-way arbing?#

The each-way one, or the extra-place calculator for promotion-driven races. Both size the win and place lays together. The standard calculator only handles one lay, so you'd work the place fraction by hand, which is where the errors start.

Are each-way arbing profits tax-free in the UK?#

Yes. It's matched betting on the bookmaker side, and HMRC treats matched-betting profits as gambling winnings, which aren't taxable income in the UK. Our tax guide covers the detail.

The practical takeaway#

Check the gap first. Before you load a calculator, compare the bookmaker's place back to the exchange place lay. If the lay isn't clearly shorter, it's a +EV bet with variance, not an arb. Size it knowing some of these lose.

Then size both legs in the calculator so the win and place lays move together, and only run any of it on accounts that are already gubbed. If you're not set up yet, you can create a free account and the tools are free to use either way. GambleAware is the right port of call if any of this starts feeling less like maths and more like gambling.