The warmest tights are high-denier opaque tights, not fleece-lined ones. At 80 or 125 denier, a thick, super-soft opaque knit traps warmth without the bulk of a fleece lining, so it still works under trousers, boots and tailoring. If you really feel the cold, the warmest pair Heist makes is The 125 Nano Opaque; for everyday winter warmth, 80 denier is the sweet spot.
Here is what actually makes tights warm, how thermal and fleece-lined compare, and which pair to choose for a British winter.
What makes tights warm
Two things: denier and yarn. Denier is the weight of the yarn, and the higher it goes the more opaque and insulating the tight (our denier guide explains it in full). Above about 60 denier a tight reads as properly warm; at 80 and 125 denier it is genuinely cold-weather kit.
The yarn matters just as much. Heist tights are knitted from a thick, super-soft yarn that holds warmth close to the leg while staying soft rather than scratchy. That is how you get warmth without the heavy, rubbery feel of cheap thick tights.
Thermal, opaque or fleece-lined?
Fleece-lined tights add a brushed inner layer for warmth, but that bulk can read as heavy and is hard to wear under slim trousers or a tailored boot. Heist takes the other route: warmth built into a sleek, high-denier opaque knit, so the tight stays slim enough to layer and smart enough for work.
For the warmest Heist option on the coldest days, layer with the Contour seamless legging, or reach for 125 denier. The result is thermal-level warmth that still looks like hosiery, not a base layer.
Which denier for winter
The Sixty, 60 denier
Everyday winter warmth. The Sixty Opaque is fully opaque and warm enough for milder winter days and layering season.
Good for: mild winter days, layering season.
The Eighty, 80 denier
The cold-weather sweet spot. The Eighty Opaque uses a thicker, super-soft yarn that holds warmth in for most of a British winter.
Good for: most of winter, work and everyday.
The 125 Nano, 125 denier
The warmest Heist makes. The 125 Nano Opaque is dense and insulating while staying soft and sleek.
Good for: the coldest days, outdoors, anyone who feels the cold.
How to wear warm tights
Warm tights are the backbone of a winter wardrobe. A few ways to wear them:
Under trousers and tailoring. A slim opaque tight adds a warm layer with no bulk, so wide-leg trousers and tailored boots still sit cleanly.
With boots and knit dresses. 80 or 125 denier opaque with ankle or knee boots and a longline knit is the easiest warm winter outfit.
In winter colour. Black is the workhorse, but slate grey, midnight navy and burgundy opaques (see the Cold Weather Tights collection) feel more considered than black alone. The high-waisted waistband keeps everything in place under closer-cut pieces (more in our high-waisted tights guide).
Why Heist tights keep you warm and last
Warmth is only half of it. Heist tights are engineered to survive a full winter of wear: the yarn carries up to ten times the spiral density of a standard tight (around 5,000 nylon spirals per inch of elastane), so they resist snags and ladders, and the seamless 3D-knit construction has a single seam under the toe with an engineered high-waisted waistband that does not dig, roll or fall down. We developed the fit across 196 samples tested on 67 women, and customers regularly report pairs lasting years. A warm tight that survives several winters is far better value than a cheap thick pair that ladders in weeks.
Shop cold weather tightsFrequently asked questions
What are the warmest tights?
The warmest tights are high-denier opaque tights, typically 80 to 125 denier. The thicker the opaque knit, the more it insulates. Heist's warmest is The 125 Nano Opaque, with The Eighty at 80 denier as the everyday winter choice. Fleece-lined tights add warmth too, but with more bulk.
Are fleece-lined tights warmer than thermal opaque tights?
Fleece-lined tights can feel warmer because of the brushed inner layer, but they are bulkier and harder to wear under slim trousers or boots. A thick high-denier opaque tight (100 denier and above) gives comparable warmth in a slimmer, smarter form that layers more easily.
What denier is best for winter tights?
80 denier is the sweet spot for most of a British winter. Choose 125 denier for the coldest days or outdoor wear, and 60 denier for milder days and layering season.
Can you wear opaque tights under trousers?
Yes. A slim high-denier opaque tight adds a warm layer without bulk, so it works under trousers, tailoring and boots where a fleece-lined tight would be too thick.
Are thermal tights worth it?
If they last, yes. A well-made thick opaque resists laddering and keeps its shape for several winters, which makes the cost-per-wear low. A cheap thick pair that ladders in weeks works out more expensive over time.
Words by The Heist Team.
