Buy military surplus boots in the wrong size and you'll find out on the first proper walk — heel slip, black toenails, or feet swimming inside a boot built for someone two sizes bigger. This military boots size guide covers measuring, sizing conversions and the fit checks that actually matter before you commit to a pair of surplus boots in 2026.
- AKU Pilgrim GTX boots run true to UK sizing at MilitaryMart — buy your usual size.
- Grade A Haix and Lowa surplus mountain boots often come up half a size small — size up.
- Wear the sock system you'll actually use on the walk when trying boots, not bare feet.
- Break in leather military boots over two weeks before a long yomp or wild camp in 2026.
Why this matters
A misjudged size on a £15 pair of trainers is annoying. A misjudged size on a pair of AKU Pilgrim GTX boots or Grade A Haix mountain boots is a wasted afternoon and a return you didn't want to deal with. Surplus and ex-issue boots don't follow one clean sizing chart — a German army boot, a Swedish army boot and a British issue boot can all come up differently even at the same stated size.
MilitaryMart sells genuine and Grade A surplus footwear from several forces, and the sizing note on each listing exists for a reason. Read it before you buy, not after the parcel arrives. Get the fit right first time and the boots will do their job for years — get it wrong and no amount of break-in fixes a boot that's simply the wrong shape.
What you'll need
- A tape measure, or a sheet of paper and a pen for a foot trace
- The socks you'll actually wear on the walk — not bare feet
- An hour in the afternoon, when feet are at their largest for the day
- A well-fitting boot or walking shoe already in your wardrobe, for comparison
- 15 minutes to lace up properly and walk, not just stand still in the shop or the hallway
The steps
1. Measure both feet properly
Stand on a sheet of paper in the afternoon and trace around each foot with a pen held vertical. Measure the longest point (heel to toe) and the widest point across the ball of the foot. Most people have one foot slightly bigger than the other — size for the larger one, always.
This single step avoids the most common mistake: sizing from memory or from a shoe you bought five years ago. Feet change shape and length slightly with age and with the socks you wear day to day.
Common mistake: measuring first thing in the morning, when feet are at their smallest of the day.
2. Understand the sizing system on the listing
Surplus boots come from several forces and several sizing conventions — UK, European, and mondopoint are all in circulation. A German or Swiss army boot marked in a continental size won't match a UK boot marked with the same number. Check the sizing note on each product page before ordering; it's there specifically because surplus doesn't follow one universal chart.
When a listing says "true to size" or "comes up small," that's the actual grading note from someone who's handled the stock, not a guess.
3. Match your sock system to the boot
The socks you wear change the fit more than most people expect. A thick hiking sock adds real bulk around the foot and ankle; a thin liner sock barely changes the fit at all. Try boots on with the exact sock system you plan to use on the walk or wild camp, and the 1000 Mile walking sock mens twin pack is a reasonable stand-in for testing if you don't already own a hiking sock.
Expected outcome: the boot should feel snug through the heel and midfoot with your actual sock on, not with a thin cotton sock you'd never wear on a proper walk.
4. Factor in the grading on used surplus
Grade A boots have seen genuine service use, and the leather and insole can pack down slightly differently to new stock even at the same stated size. The Haix SF GTX Commander German Army Mountain Boots Grade A is a good example — issue-worn Bundeswehr mountain boots that often need a half size up from what you'd order new, because the previous wearer's foot has already shaped the leather.
New or new-spec boots don't carry this quirk — they're closer to a straight size conversion. Grade always changes the calculation, so check it before you order.
Common mistake: ordering Grade A surplus in the exact same size as a brand-new boot from a different brand, without reading the condition note.
5. Check toe room and heel lock, not just overall length
Lace the boot fully and kick your toes forward gently. You should be able to fit roughly a thumb's width — about 1cm — between your longest toe and the front of the boot. Too tight here and toes hammer the front on any downhill stretch; too loose and your foot slides forward with every step, which wrecks toenails on a long walk.
Then check the heel: with the boot laced properly, your heel shouldn't lift more than a few millimetres when you walk. Heel lift of a centimetre or more means the boot is either too big overall or the wrong last shape for your foot.
6. Walk in them before you commit to a long day
Don't judge fit from standing still. Lace the boots properly, walk around for 10–15 minutes on a hard floor, go up and down a step if you can. Leather military boots, in particular, need a genuine break-in period — plan on two weeks of shorter walks before you trust them on a full day's yomp or a wild camp weekend.
Expected outcome: no hot spots, no heel movement, no pressure across the top of the foot by the time you take them off.
7. Don't size down expecting break-in to fix a tight fit
Leather stretches a little with wear, but it doesn't stretch enough to fix a boot that's genuinely too small. Buying tight on the theory that "they'll loosen up" is the single most common sizing mistake with surplus boots, and it usually ends with blisters on the first proper outing rather than a perfect fit by week three.
Troubleshooting
Heel slips in the first week of wear Re-lace using a heel-lock (surgeon's knot) at the top eyelets, or add a thin insole to take up volume. If slip continues after that, the boot is likely half a size too big.
Toes hit the front on downhill stretches This points to a boot that's too short, not too narrow. Go up half a size rather than adding a thicker sock, which won't solve a length problem.
Grade A boots feel noticeably narrower than new stock of the same size This is normal — issue-worn leather has already taken the shape of a previous wearer's foot. Check the listing's condition note; a wider-fitting alternative may be listed separately.
Boots felt fine trying on, tight after a full day out Feet swell through the day, especially on a long walk. Always size for the afternoon fit, not the fit first thing in the morning.
You measure exactly between two sizes Size up for military boots rather than down. A slightly roomy boot with a good sock system beats a tight boot every time on a long walk.
Half sizes aren't listed for the model you want Most surplus ranges run in whole sizes only, inherited from the original issue sizing. Go up rather than down when a half size isn't stocked.
Tools and resources
- AKU Tactical® KS Schwer 14 GTX® N Boots — new Swiss Army-spec boots with a straightforward true-to-size fit, useful as a reference point if you're unsure how a surplus size compares
- A tape measure or paper trace kit, kept by the front door for future boot purchases
- The condition and sizing note on each MilitaryMart boot listing — read it every time, even if you've bought the same model before
- A hiking sock you already trust, worn during the fitting, not just during the walk
What to do next
Once the fit is sorted, think about what's going in your bag around those boots. If wild camping or a bushcraft trip is the reason you're buying boots in the first place, the guide on military surplus backpacks for bushcraft and wild camping covers the same practical sizing approach applied to a rucksack — get both right and the rest of the kit list falls into place.
FAQ
What size should I buy in military boots?
Measure both feet in the afternoon and buy to the larger foot's length, with the socks you'll actually wear. Military surplus sizing varies by force, so always check the listing's condition and sizing note before ordering.
Do German army surplus boots run small?
Grade A German boots like the Haix SF GTX Commander often come up half a size small because issue-worn leather has already taken a previous wearer's shape. New-spec German boots follow a straighter size conversion.
Should I size up or down for combat boots?
Size up when you're between sizes. A slightly roomy combat boot with a proper sock beats a tight one on any walk longer than an hour.
How long does it take to break in leather military boots?
Plan on two weeks of shorter walks before trusting leather military boots on a full day out in 2026. Break-in softens the leather around the ankle and forefoot but won't fix a genuinely undersized boot.
What socks should I wear with military boots?
A proper hiking sock, such as the 1000 Mile walking sock twin pack, adds enough bulk to change the fit noticeably compared with a thin cotton sock. Always fit boots with the sock system you'll actually wear.
Is Grade A sizing the same as new-issue boot sizing?
No. Grade A surplus has seen genuine service wear, and the leather and insole can pack down differently to new stock at the same stated size. Read the condition grading on each listing before ordering.
Are half sizes available in military surplus boots?
Most surplus ranges run in whole sizes only, carried over from the original issue sizing system. When a half size isn't stocked, go up rather than down.
How do UK sizes compare with continental military sizing?
UK, European and mondopoint sizing all appear across surplus stock from different forces, and the same number doesn't mean the same fit across systems. Check the specific sizing conversion note on each product listing rather than assuming a direct match.
One last thing
The sizing note on a Grade A listing isn't boilerplate — it's usually written by someone who's had that specific batch of boots in their hands. If a listing says a model comes up small, believe it and size up rather than betting on your usual number; that one line saves more returns than any measuring chart.
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