What Is A Gammon Joint?

Gammon is raw, cured pork — usually cut from the leg or shoulder — sold ready to cook rather than ready to eat. The curing is what gives it that pink colour and salty edge, but it still needs to go through a full cooking process before it's safe on the plate. Once it's cooked, the same joint is technically called ham, which is why "gammon" and "ham" so often get used for the same piece of meat. If a recipe or a label says gammon, assume it's raw and needs the full cook time; if it says cooked ham or honey roast ham, it's usually ready to eat cold or just needs reheating, not cooking from scratch.

How Long To Cook A Gammon Joint

There's a reliable rule behind every gammon cooking time, and it's worth knowing even if you let the calculator do the maths: for boiling, allow 20 minutes per 450g plus 20 minutes on top; for oven roasting, it's 30 minutes per 450g plus 30 minutes. A joint that's glazed gets an extra 15–30 minutes in a hot oven at the end to colour and set the glaze, and a joint cooked from frozen needs roughly 50% longer on the main cooking stage — though checking with a thermometer always beats trusting the clock.

Those two rules cover boiling and roasting. Slow cookers and pressure cookers work to their own timings, which the two tables further down cover separately, since "minutes per 450g" doesn't really apply once the joint is submerged under pressure or cooking unattended for hours.

Gammon Cooking Times Per Kg

Use this gammon cooking times chart as a quick reference for boiling and oven-only roasting. These are cook times only — add roughly 12 minutes for resting before you carve, and 15–30 minutes more if you're finishing with a glaze.

Got an odd weight, like 1.8 kg or 2.3 kg? That's exactly what the calculator above is for — type in your joint's exact weight and it works out the precise time rather than rounding to the nearest half kilo.

Boil vs Roast vs Slow Cooker vs Pressure Cooker

None of the four methods is objectively "best" — they're trade-offs between time, hands-on effort, and how much oven space you've got free. Boiling first, then finishing with a short glaze in a hot oven, is the classic route: it keeps the meat moist and gives you a sticky, caramelised top without tying up the oven for hours. Roasting the whole way through is simpler — one pan, one appliance — but needs closer attention so the outside doesn't dry out before the centre's done. A slow cooker is the walk-away option: it takes the longest by a wide margin, but it also frees up your oven and hob completely, which matters a lot on a day when you're cooking several things at once. A pressure cooker or Instant Pot is the opposite — by far the fastest route to a cooked joint, useful when you've forgotten to start early or just want gammon on a weeknight.

Slow Cooker Gammon Cooking Times

A slow cooker gammon cooking time doesn't scale neatly by weight the way boiling and roasting do — most joints between 1kg and 3kg fall into a fairly narrow 6–9 hour window on low, since the slow, steady heat does the real work regardless of size. Sit the joint in the pot, cover with stock, cider or apple juice, lid on, and leave it — then finish under a hot grill for 10–15 minutes if you want a sticky glazed top. One thing worth knowing: a slow cooker isn't a safe way to cook a joint from frozen, since it can sit too long at a low temperature before it comes up to a safe heat. Always thaw fully in the fridge first if you're using this method.

Pressure Cooker & Instant Pot Gammon Cooking Times

Pressure cooking is the quickest way to get a gammon joint from raw to rested, and it's a genuinely useful shortcut for anyone using an Instant Pot, Ninja Foodi or stovetop pressure cooker. Figure on roughly 25 minutes of cook time per kilo on high pressure, plus 10 minutes or so for the cooker to come up to pressure first, and another 10 minutes of natural release once the cooking time ends — don't force the valve open early. If you want a glazed finish, the joint still needs 15–30 minutes in a hot oven afterwards; pressure cooking gets the meat cooked through, but it won't give you that caramelised top on its own.

What Temperature Should Gammon Be Cooked To?

A gammon joint is safely cooked once the thickest part — away from any bone — reads 71°C on a probe thermometer. That sits comfortably above the UK Food Standards Agency's minimum safe-cooking guidance, and lines up with food-safety recommendations in most other countries too — it's the one number worth actually checking rather than guessing: cured meat like gammon stays pink even when it's fully cooked, so colour and clear juices aren't a reliable test the way they are with a chicken. A cheap digital probe thermometer, pushed into the centre of the joint away from fat or bone, takes the guesswork out completely.

How Much Gammon Do I Need Per Person?

As a rough guide, raw gammon loses a little weight as it cooks and rests, most guidance works on 185–220g of raw joint per person depending on appetite. A smaller "light" portion is closer to 150g a head, while a hearty Christmas-dinner-sized portion runs to around 220g. The table below shows what that means for a typical group of 8.

Cooking Gammon From Frozen

It's possible to boil or roast a gammon joint from frozen, but it takes noticeably longer — plan on roughly 50% more time on the main cooking stage, and lean on a thermometer rather than the clock to confirm it's actually reached 71°C all the way through, since a frozen centre can lag well behind a thawed outer layer. A slow cooker isn't suitable for a frozen joint at all; the long, low heat means the centre can sit in an unsafe temperature range for too long before it catches up. Where you've got the time, defrosting fully in the fridge first — usually a day or two for a typical joint — gives the most even, predictable result.

How To Use This Gammon Cooking Calculator

The calculator above is built to answer one question — "what time do I need to start cooking?" — without you having to do any of the maths yourself. Here's what each part of it does.

Joint weight

Type your gammon's raw weight directly into the box, use the slider underneath it, or tap the plus and minus buttons to nudge it up or down. Switch between kg and lb with the toggle at the top — every time and temperature on the page updates instantly as you change the weight.

Cooking method

Pick from five methods: Classic (boil, then a short glaze-roast to finish — the most common route), Roast (oven the whole way through, covered then uncovered), Boil (stovetop only, with an optional glaze finish), Slow cooker (hours of hands-off cooking, with an optional grill finish), and Pressure cooker (the fastest option, for an Instant Pot or stovetop pressure cooker). Each one shows its own description, timeline and oven temperature.

Glaze finish

Switch the glaze toggle on for a scored, studded, lacquered finish, and pick a flavour — honey & mustard, marmalade, maple & sugar, or pineapple & clove. Turning it off skips straight to a plain, crisp finish with no extra oven stage.

Cooking from frozen

Flip this on if your joint hasn't been defrosted, and the calculator adds roughly 50% to the main cooking stage. It's disabled for the slow cooker method, since cooking a frozen joint that way isn't considered food-safe.

Set serving time

Instead of working backwards yourself, switch this on, enter the time you want to eat, and the calculator tells you exactly what time to start cooking — and warns you if your chosen time is simply too tight for the joint you've entered.

Guests & units

Open this panel to get a suggested joint size based on your number of guests and appetite (light, standard or hearty), switch between kg and lb, and choose whether the oven temperature is shown in °C or °F throughout.

Cooking plan & timer

Tap "Full plan" for a complete step-by-step breakdown with tips for every stage, or "Start cooking timer" to run a live countdown that walks you through each phase with a beep between steps. From the plan sheet you can copy the whole thing to your clipboard or print it out to keep by the hob.

Frequently Asked Questions

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