Where can I buy bay windows online?

You can design and buy a made-to-measure uPVC bay window on our bay designer. Choose 2 to 7 frames, any corner from 45° to 179°, the style and width of each frame, and the colours and glass. The designer works out the backspan, projection, bay poles and cill welds and shows the full price including VAT as you go. For example, a three-frame 135° bay 1,250mm high with a 2,219mm internal backspan is £863.64 in white, and a 2.4m bay in Anthracite Grey outside and white inside is £959.33. We make every frame at our Worsley factory and supply it ready for your fitter.

What is a bay pole, and which one do I need?

A bay pole joins two frames at a corner of the bay, so there is one at every corner. There are three types. A 90° corner takes a 90° pole, a corner from 134° to 136° takes a 135° pole, and any other angle takes a variable pole. The designer picks the right pole for each corner. Each pole is as long as the frame height: the overall height less the 30mm cill face when you choose a cill, so a 1,200mm bay with a cill has 1,170mm poles, £70.20 each. Poles cost £60 per metre including VAT, charged by their exact length. Measure each internal width to the centre of the pole: we deduct for the poles when we make the frames.

How much does a bay window cost?

Each frame costs the same as that window on its own, at the internal width you enter and the bay's overall height. On top, there's a bay pole at each corner, at £60 per metre. Each pole is as long as the frame height: the overall height less the 30mm cill face when you choose a cill, so a 1,200mm bay with a cill has 1,170mm poles, £70.20 each. Each cill weld is £25, one per corner when you choose a cill. All prices include VAT at 20%. For example, the bay the designer opens with is £809.81 including VAT: a three-frame splayed bay with an internal backspan of 2,049mm, 1,200mm high, top section 400mm high on frame 2, in white, double glazed (28mm) with a 150mm cill, frame 1 hinged on the left, frame 3 hinged on the right (seen from outside). A common bay about 2.4m across is £959.33 including VAT: a three-frame splayed bay with an internal backspan of 2,390mm, 1,300mm high, in Anthracite Grey outside and white inside, double glazed (28mm) with a 150mm cill, frame 1 hinged on the left, frame 3 hinged on the right (seen from outside). A three-section splayed bay 1,250mm high is £863.64 including VAT: a three-frame splayed bay with an internal backspan of 2,219mm, 1,250mm high, top section 400mm high on frame 2, in white, double glazed (28mm) with a 150mm cill, frame 1 hinged on the left, frame 3 hinged on the right (seen from outside). A five-section bay 1,200mm high is £1,127.64 including VAT: a five-frame bay with an internal backspan of 2,616mm, 1,200mm high, top section 400mm high on frame 3, in white, double glazed (28mm) with a 150mm cill, frame 1 hinged on the left, frame 5 hinged on the right (seen from outside). A box bay with top openers on the sides and a side opener at the front is £739.73 including VAT: a three-frame box bay with an internal backspan of 800mm, 1,200mm high, top sections 400mm high on frames 1 and 3, in white, double glazed (28mm) with a 150mm cill, frame 2 hinged on the left (seen from outside). Each price opens the designer at exactly that bay. Delivery is extra, from £30 by distance from our factory, or collect free: see delivery and collection.

Can I fit a bay window myself?

You can if you're confident fitting windows, or you can use a fitter. We supply only: we make the bay to your sizes and deliver it, or you collect it, and you or your fitter fit it. We don't survey, measure or fit. If a roof or the wall above rests on the old bay, get a builder or structural engineer to support it before the old frames come out. Replacement windows in England and Wales also need Building Regulations sign-off: see FENSA and building control. Our hiring a fitter guide covers what to ask.

Can you make a corner window?

Yes. A corner window is two frames meeting at one corner post on the corner of the building, usually at 90°. In the designer it's a 2-frame bay, and its backspan is the diagonal between the two frame ends. Choose 2 frames in the designer. Both frames are end faces: measure each one's internal width inside the room, from the end of the old frame to the centre of the corner post, or measure from the plaster line. Measure the angle inside the room too: a 90° corner takes a 90° pole. It's priced like any bay: the two frames, one bay pole and, with a cill, one cill weld. If the wall or a roof above rests on the old frames or the corner post, get a builder or structural engineer to support it before the old frames come out.

Can I choose which side the windows open?

Yes. Any frame whose style isn't the same both ways round, such as the Full Side Opener, can be made either way round in the designer, so it opens on the side you want. Choose which way round each frame is made, seen from outside, the way we draw and make windows. The price is the same either way. We number the frames left to right as seen from outside, the way we draw and make them. Standing inside looking out, frame 1 is the one on your right. The designer starts with the end frames hinged against the wall: frame 1 hinged on the left and the last frame hinged on the right, seen from outside.

How do I measure a bay window?

Measure the height outside, and the widths and angles inside the room. The overall height is the external size of the frames, with the new uPVC cill included. Measure it outside, from the bottom of the old cill, where it sits on the brickwork, up to the underside of the head (the lintel or beam the old frames sit under), at each end and at every corner. Use the smallest and take 10mm off: that's the overall height of the whole bay. Don't add anything for the new cill: it goes where the old one was, inside this height. The old cill always comes out, so never measure from the top of it. For the widths, which are all internal widths, measure each face inside the room from the centre of one corner pole or post to the centre of the next. Measure an end face from the end of the old frame, or from the plaster line, to the centre of the pole. Measure every width at the top, middle and bottom, and use the smallest. Don't take anything off the widths, not for the poles and not the 10mm you'd take off a flat window. We make the deductions when we make the frames. Then measure the angle at each corner, inside the room, and check the backspan. Our bay measuring guide takes you through it step by step.

How long does a bay window take?

Typically 5-14 working days, the same as our other windows. Every bay is made to order at our Wardley factory in Worsley, Manchester. We confirm your delivery or collection date when we confirm your order, usually within one working day.

How much is delivery for a bay window?

Delivery is extra, from £30 by distance from our factory, or collect free: see delivery and collection. It's charged once per delivery, however many items are on it, and the basket shows it before you pay.

uPVC bay windows, made to measure

Build a uPVC bay from the windows we already make. Choose 2 to 7 frames, a style and an internal width for each one, and the angle at each corner, anywhere from 45° to 179°. We work out the internal backspan, the bay poles and the price as you go. Supply only: we make every frame at our Wardley factory in Worsley, Manchester, and deliver the bay. You arrange the fitting.

For example, a three-frame splayed bay with an internal backspan of 2,049mm, 1,200mm high, top section 400mm high on frame 2, in white, double glazed (28mm) with a 150mm cill (sill), frame 1 hinged on the left, frame 3 hinged on the right (seen from outside), is £809.81 inc VAT, delivery extra. It's the bay the designer below opens with.

Made to order, typically 5-14 working days
10-year frame guarantee against discolouration and warping
Delivery from £30 by distance, or collect free
Single windows

How to measure a bay

Read the full guide

Every width is an internal width: measure it inside the room, along the inside of the bay, never outside.

Measure the overall height outsideThe overall height is the external size of the frames, with the new uPVC cill included. Measure it outside, from the bottom of the old cill, where it sits on the brickwork, up to the underside of the head (the lintel or beam the old frames sit under), at each end and at every corner. Use the smallest and take 10mm off: that's the overall height of the whole bay. Don't add anything for the new cill: it goes where the old one was, inside this height. The old cill always comes out, so never measure from the top of it.
Measure the internal width of each faceAll widths are internal, measured inside the room: from the centre of one corner pole or post to the centre of the next. End faces: from the end of the old frame (dig the plaster back to see it), or measure from the plaster line. Measure at the top, middle and bottom, and use the smallest. Don't take anything off the widths, not for the poles and not the 10mm you'd take off a flat window. We make the deductions when we make the frames. We number the frames left to right as seen from outside, the way we draw and make them. Standing inside looking out, frame 1 is the one on your right.
Measure the angle at each cornerMeasure inside the room, between the two faces. 135° is the usual splayed bay and 90° a square (box) bay. We number the corners the same way: corner 1 is between frames 1 and 2, the corner furthest to your right as you stand inside looking out. Some angle finders read the outside of the corner. On a bay, if yours shows a small angle such as 45° or 30°, take it away from 180°: 45° means 135° inside, and 30° means 150°. No angle finder? The full guide shows how to find the angles with a tape.
Check the backspanMeasure straight across the inside of the bay, between the same two points you measured the end faces from. It should match the backspan we work out within about 5mm. If you measured the end faces from the plaster line, tick "I measured the end faces from the plaster line" under the backspan and the designer shows the figures to expect plaster line to plaster line.

A tall bay? Full side openers, and other styles where an opener runs the full height of the frame, stop at 1,330mm with a cill, 1,300mm with no cill. The Top Opener over Fixed goes much taller, up to 2,530mm with a cill. The designer only offers the styles that can be made at your height. See which styles suit which sizes.

Your bay from above

Internal widths, measured inside the room. Standing inside looking out, frame 1 is the one on your right.

Internal backspan

2,049mm

Projection

424mm

I measured the end faces from the plaster line

Check it: measure straight across the inside of the bay, between the same two points you measured the end faces from, and out to its furthest point for the projection. Yours should match ours within about 5mm. If you measured the end faces from the plaster line, tick "I measured the end faces from the plaster line" under the backspan in the designer: it then shows the backspan and projection to expect plaster line to plaster line, with your widths left as they are. If they don't match, check your widths and angles before you order.

Frames side by side

Drawn to scale. Seen from outside, the way we draw and make them, so frame 1 is on the left.

Price per bay

£809.81inc VAT

1. Frames and height

Bay window, 3 frames

How many frames (faces) the bay has, from 2 to 7.

Overall height (external, cill included)

Measure outside, from the bottom of the old cill, where it sits on the brickwork, up to the underside of the head (the lintel or beam the old frames sit under), at each end and at every corner, and take 10mm off the smallest. Don't add anything for the new cill: it goes where the old one was, inside this height. With the styles and widths you've chosen, the overall height can be from 730 to 1,330mm. Other styles go taller.

Transom height (top section)

Every frame with a transom has it at the same height, so the transoms line up across the bay. Transoms sit 400mm down from the top of the frame as standard. If the opener or the glass below would then be too big to make, as on a tall bay, we drop them just enough to make it a size we can make. On a very low bay we raise them a little instead. The top section runs from the top of the frame to the centre of the transom. Frame 2 has a transom. At these sizes its top section can be 400 to 870mm high.

Not sure how to measure? How to measure a bay window

2. Frame styles and widths

Backspan 2,049mm

Every width is an internal width: measure it inside the room, along the inside of the bay, never outside.

We number the frames left to right as seen from outside, the way we draw and make them. Standing inside looking out, frame 1 is the one on your right. To check, choose Inside View on the frames side by side: it shows the bay as you see it from the room.

Don't take anything off the widths, not for the poles and not the 10mm you'd take off a flat window. We make the deductions when we make the frames.

Choose which way round each frame is made, seen from outside, the way we draw and make windows. The price is the same either way.

Frame 1end frame, wall on the left (seen from outside), on your right from inside
£178.16
Full Side Opener
1 side opener
Internal width
From the end of the old frame to the centre of the pole or post, or measure from the plaster line. Use the smallest of top, middle and bottom. At this height, this style can be made 500 to 900mm wide.
Which way round (seen from outside, the wall on the left)
Frame 2
£263.09
Top Opener over Fixed
1 top opener over a fixed pane
Internal width
From the centre of one pole or post to the centre of the next. Use the smallest of top, middle and bottom. At this height, this style can be made 500 to 1,300mm wide.
Frame 3end frame, wall on the right (seen from outside), on your left from inside
£178.16
Full Side-Hung Window
1 side opener
Internal width
From the end of the old frame to the centre of the pole or post, or measure from the plaster line. Use the smallest of top, middle and bottom. At this height, this style can be made 500 to 900mm wide.
Which way round (seen from outside, the wall on the right)

Internal backspan

2,049mm

Projection

424mm

3. Corner angles

2 corners

Measured inside the room, between two frames: 135° is the usual splayed bay and 90° a box bay. Any angle from 45° to 179°.

Some angle finders read the outside of the corner. On a bay, if yours shows a small angle such as 45° or 30°, take it away from 180°: 45° means 135° inside, and 30° means 150°.

No angle finder?

Enter your widths in the designer exactly as you'll order them. If you measured the end faces from the plaster line, tick "I measured the end faces from the plaster line" under the backspan. Then change the angle until the backspan and projection the designer shows match your own. It's less exact than measuring each angle, so borrow a sliding bevel or an angle finder if you can. Check your angles from the backspan

Same angle at every corner

Angle at every corner

Both corners take a 135° pole.

Each corner takes a bay pole as long as the frame without its cill (1,170mm): a 90° pole for a 90° corner, a 135° pole from 134° to 136°, and a variable pole for any other angle.

4. External frame colour

White

Seen from the street. Foiled woodgrain finishes are textured like real timber. Picking a colour sets the inside to white; choose Same as external below for colour on both sides. Window colours explained (opens in a new tab)

5. Internal frame colour

Same as external

Dual colour: choose a different colour for the room side of your frames. Use the Inside View button on the drawing to preview it.

6. Handle colour

White

Locking espagnolette handles fitted to every opener. Handles and locks explained (opens in a new tab)

7. Locks

Espag lock (standard)

Key-locking espagnolette multi-point locking is included on every opener. Upgrade to a Quad Lock per opener.

8. Hinge type

Standard friction hinge

Every side opener has egress hinges as standard. Standard friction hinges are included. Restrictor hinges limit how far each sash opens, are priced per opening sash, and can be chosen on fire escape windows too.

9. Glazing

Double glazed (28mm)

Complete unit price including the glass. Units are argon filled with warm-edge spacers. Toughened safety glass is required within 800mm of floor level or 300mm of a door. Double or triple glazing? (opens in a new tab)Where safety glass is required (opens in a new tab)

Low bay? Measure inside, from the floor to the bottom of the old window frame. If that's under 800mm, the glass will be within 800mm of the floor, so it must be toughened safety glass: choose toughened, or ask us if you're close.

10. Privacy glass

Clear

Obscure patterns for bathrooms, WCs and street-facing rooms. The obscure glass patterns compared (opens in a new tab)

11. Cill

150mm cill

The old cill always comes out, and the new cill is part of the overall height. The 150mm cill, the same as our windows, is chosen for you. The 150mm is how deep it is, front to back: every cill is 30mm tall, and that's inside your overall height. Choose the 180mm or 225mm cill if you need one deeper to reach past the brickwork below, so rain drips clear of the wall. Only choose the 85mm stub cill or No cill if your fitter asks for it. Not sure? Ask us before you order.

On a bay the frames' cills are welded together at each corner: £25 a corner.

12. Trickle vents

2000 vents (300mm)

Building Regulations (Part F) require background ventilation in most replacement installs. 2000 vents suit narrower openers; 4000 vents move more air but need a wider sash. Trickle vents and Part F explained (opens in a new tab)

If a vent is too long for a frame's openers, that frame has the next size down.

Price per bay

£809.81

inc VAT · made to your sizes

Qty

Price breakdown

Frame 1: Full Side Opener, hinged on the left (seen from outside), against the wall, 600mm internal width, 1,200mm overall height: £178.16
Frame 2: Top Opener over Fixed, 1,200mm internal width, 1,200mm overall height: £263.09
Frame 3: Full Side-Hung Window, hinged on the right (seen from outside), against the wall, 600mm internal width, 1,200mm overall height: £178.16
Top section 400mm high on frame 2: Included
Corners 135° and 135°: 2 × 135° polesBay poles at £60 per metre, each as long as the frame without its cill (1,170mm): £140.40
Cill welds: 2 × £25: £50.00
Total per bay inc VAT: £809.81

Backspan 2,049mm, overall height 1,200mm, projection 424mm, top section 400mm high on frame 2, 150mm cill. Delivery is extra, from £30 by distance from our factory, or collect free. Delivery and collection

Made to the exact sizes you enter, so please check them. Free to cancel until we confirm your delivery or collection date, usually within one working day, but no change-of-mind returns. Returns & refunds

£809.81inc VAT

Backspan 2,049mm

uPVC bay window prices 2026: how we work them out, supply only

Each frame is priced exactly as the same window on its own, at the internal width you enter and the overall height of the bay, with the options you choose for the bay. Every frame with a transom has it at the same height, so the transoms line up across the bay. Transoms sit 400mm down from the top of the frame as standard. If the opener or the glass below would then be too big to make, as on a tall bay, we drop them just enough to make it a size we can make. On a very low bay we raise them a little instead. You can set your own transom height in the designer, and each frame is priced with it.
Bay poles are £60 per metre, charged by exact length. There is one at each corner, as long as the frame height: the overall height less the 30mm cill face when you choose a cill, so a 1,200mm bay with a cill has 1,170mm poles, £70.20 each. With no cill, they're the full overall height. A 90° corner takes a 90° pole, a corner from 134° to 136° a 135° pole, and any other angle a variable pole.
Cill welds are £25 at each corner when you choose a cill. With no cill, there are none.
All prices include VAT, and delivery is extra. Website prices are our trade prices, the same for everyone.

Worked examples

Priced live by the designer above. Each one opens in the designer at exactly that bay and price, so you can start from it and change anything.

The bay the designer opens with: £809.81 inc VAT

3 frames with these internal widths, left to right as seen from outside: Full Side Opener 600mm hinged on the left (seen from outside), Top Opener over Fixed 1,200mm and Full Side-Hung Window 600mm hinged on the right (seen from outside); 135° at both corners, with two 135° poles; 1,200mm overall height including the cill (internal backspan 2,049mm, projection 424mm); top section 400mm high on frame 2; white inside and out; double glazed (28mm); clear glass; 150mm cill with 2 cill welds; trickle vents: 2000 (300mm); white handles; standard key-locking espag lock.

Frame 1: Full Side Opener, 600 × 1,200mm: £178.16
Frame 2: Top Opener over Fixed, 1,200 × 1,200mm: £263.09
Frame 3: Full Side-Hung Window, 600 × 1,200mm: £178.16
2 bay poles, 1,170mm each: £140.40
2 cill welds: £50.00
Total, including VAT at 20%: £809.81