Best Lay Stake Calculators UK 2026: 6 Tools Compared

Every calculator on this page does the basic job: enter back stake, back odds, lay odds and commission, and out pops a lay stake, a liability figure, and a profit number. The differences show up in the edge cases that bite later - and that is where a bad calculator silently costs you money.

The criteria worth weighting:

• Bet-type coverage - at minimum, Qualifying, Free Bet SNR (stake not returned), and Free Bet SR (stake returned). The two free-bet modes use different formulas and confusing them is the most common rookie mistake.
• Exchange commission input - Betfair defaults to 5%, Smarkets and Matchbook are effectively 0%. A calculator that hard-codes 5% will hand you wrong numbers on the commission-free exchanges. See how betting exchanges work for the wider context.
• Underlay / overlay split - splitting a qualifier so a small loss lands on the back side (overlay) helps your account look like a recreational punter rather than a value-seeker. Worth having even if you do not use it every day.
• Mobile usability - most of your offers land in the morning while you are looking at the bookmaker app. A calculator that refuses to render on a phone is dead weight.
• Specialised siblings - each-way, extra place, dutching, multi-lay. You will eventually need them. Tools published as part of a wider suite tend to win here.

OddsMonkey's calculator is the one most paid matched-betting subscribers reach for, mainly because it is wired directly into the rest of the platform: open an offer on the Daily Offer Calendar, click through, and the calculator is pre-populated with the bookmaker, the stake type, and a reasonable starting commission. That integration is the actual reason you pay for it - running the calculator standalone is no faster than the free options below.

The Premium tier carries a published price of around £39.99 per month or £249.99 per year, with a trial that lets you walk through a real offer before subscribing. Most of the bundled tools - Racing Matcher, Each Way Matcher, Dutch Matcher, AccaMatcher - wrap calculators of their own, so a Premium account effectively means you stop thinking about calculation entirely and just react to outputs.

The trade-off is exactly what you would expect: paying £40/month for a tool you could replicate with two free tabs only makes sense once you are pulling several hours a week of matched-betting time and the oddsmatcher saves you more than the price in offer-discovery alone.

Outplayed is the rebrand of Profit Accumulator and is now run under the same parent company as OddsMonkey - the underlying calculator engine, the offer-coverage style, and even some of the educational flow look familiar to anyone who has used both. The free public calculator on outplayed.com supports the three core bet modes (normal qualifier, free bet SNR, free bet SR) and accepts back-side commission for the relatively rare case where the back leg sits on an exchange.

Pricing is cheaper at the entry level than OddsMonkey - the standard tier sits around £19.99 per month or £150 a year, with a Platinum tier around £29.99 per month or £250 a year that unlocks the wider calculator suite (each-way, dutching, etc.). The advanced calculators are gated behind Platinum - the free public calculator is deliberately the minimum-viable version.

If you are choosing between Outplayed and OddsMonkey on price alone, Outplayed wins. If you value polish and breadth of bundled tools, OddsMonkey edges it. Given the shared ownership, the gap between them in 2026 is narrower than at any point in the last five years.

AiProfit publishes a fully free matched-betting calculator alongside an unusually wide range of specialised variants for a no-paywall site: each-way (for win/place offers in horse racing and golf), extra place (for the seasonal extra-place promotions), multi-lay (for covering more than two outcomes), and dutching tools. The main calculator handles qualifying-bet and free-bet modes side by side and makes a point of asking for exchange commission rather than hard-coding it.

The clearest use case is bettors who want premium-suite feature coverage without the premium-suite price. If you do horse-racing matched betting seriously or you regularly hunt extra-place offers, having the dedicated calculators in the same place as your main one is meaningfully faster than juggling tabs.

The honest caveat with any free tool is that it lives or dies on the developer's appetite for keeping it current. The published features are accurate as of this writing; before relying on it for a large stake, cross-check against the formulas in our lay stake calculator guide.

Beating Betting's calculator is the one most readers end up bookmarking after a few weeks. The interface defaults to a clean Simple mode (three inputs, three outputs) and flips to an Advanced mode that exposes the underlay/overlay split with a slider - visually obvious what changing the split does to the back-side and lay-side outcomes. Default Betfair commission is set to 5%, which the page is upfront about reducing as the exchange's tiered rebate kicks in.

It is also the calculator most likely to render correctly on a mid-range Android phone in landscape, which sounds trivial until you try to place a £100 lay during a busy Saturday morning and the more polished sites have a layout glitch. Reliability over flash, basically.

If you also use a standalone calculator on desktop and want a phone-friendly fallback, this is the obvious pairing.

aCalculator.co.uk is the most minimal free option that still does the job competently. There is no oddsmatcher attached, no marketing funnel pushing you toward a paid tier, and no settings tab buried under a hamburger menu - just a calculator page that you can bookmark and use for years without thinking about it.

It covers the standard three bet types (Qualifying, Free Bet SNR, Free Bet SR), accepts custom commission, and outputs lay stake, liability, and the net profit/loss. There is no advanced underlay/overlay UI - if you need those splits, this is not the right pick.

For routine qualifiers and standard SNR free bets, especially in a workflow where you already have your bookmaker in one tab and your exchange in another, sometimes the calculator that does exactly the bare-minimum job and then gets out of the way is the right tool.

If you primarily lay on Smarkets, the calculator built into Smarkets' own platform is the lowest-friction option for anything routine. Smarkets publishes an official help-centre walkthrough of the lay-stake calculation methodology specific to its exchange, and the in-platform tool means you do not need to click out at all - back stake, back odds, lay odds, done.

The catch is that this only works for the exchange you happen to be on. If you run Betfair as your primary lay venue, you fall back to whichever standalone calculator from the list above suits you - Betfair's own native interface does not equivalently expose a matched-betting calculator.

Worth knowing about even if it is a secondary tool, particularly because Smarkets' low-commission positioning makes it an increasingly common second exchange to add once you outgrow the Betfair-only setup.