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Where you put a subwoofer changes the bass at your seat more than almost anything else, including which sub you bought. This calculator models how bass behaves in your room, then tests hundreds of sub positions against your seat and shows you the spots that give the smoothest result. It also lists your room’s modes and compares layouts for two or four subs.
- Enter your room size and where you sit. The front wall is the one with your TV or speakers.
- Best sub spot shows a heat map of your floor. Green is smooth bass at your seat, red is boomy or patchy. Tap the plan to try your own position.
- Room modes lists the resonances your room creates and whether each one is loud or quiet at your seat.
- Two subs compares multi-sub layouts across a three-seat sofa.
The front wall is the one with your TV or speakers. Measure the seat to where your head is.
Green areas give the smoothest bass at your seat, red the most uneven. Numbers mark the three best spots along a wall. Tap anywhere on the plan to try your own sub position.
How the calculator works
Below a couple of hundred hertz, bass in a room doesn’t behave like light from a lamp. The sound waves are long enough to bounce between your walls and form standing waves, or room modes. At some spots they pile up into a boomy peak; at others they cancel into a hole. The calculator adds up every mode in your room for each possible sub position, the same way acoustic textbooks model a rectangular room, and predicts the bass response at your seat from 20 to 160 Hz.
The “variation” figure is how much that response wanders up and down between roughly 30 and 120 Hz, in decibels. Lower is better. Under 3 dB is very smooth, 3 to 4.5 dB is good, and anything over 6 dB is the kind of uneven bass where some notes boom and others vanish.
It’s a model, not a measurement. It assumes a rectangular room with solid walls and a sub sitting near the floor. Real rooms have doorways, open-plan areas, plasterboard walls that flex and sofas that soak up bass, so treat the results as a short list of spots to try rather than a final answer. Once you’ve moved the sub, check it with the room check in our subwoofer test tones tool, or do a quick “sub crawl” as described in our subwoofer placement guide.
Room modes in plain English
Every pair of parallel surfaces creates its own set of modes. The ones between front and back walls, side walls, and floor and ceiling are called axial modes and are the strongest. Tangential modes bounce around four surfaces and are weaker, and oblique modes involve all six surfaces and are weaker still.
The first length mode is the one people notice most. Its frequency is the speed of sound divided by twice the room length, so a 20 ft room has one at about 28 Hz. It is loudest against the front and back walls and cancels completely in the middle of the room, which is why sitting dead centre often sounds thin. The room modes tab marks each strong mode as loud, quiet or in between at your seat.
Above a certain frequency, called the Schroeder frequency, modes overlap so much that the room behaves smoothly. For most living rooms that is somewhere between 100 and 200 Hz. Below it, placement is everything. Above it, your main speakers and ordinary room treatment take over.
Where to put your seat
If you can move the sofa, try not to sit exactly halfway between the front and back walls. A seat around 38% of the room length from the back wall (or about 62% from the front) avoids the worst of the first two length modes and is a good starting point. Sitting right against the back wall gives you more bass but usually boomier bass, so pulling the seat forward a couple of feet often tightens things up. Change the seat position in the calculator and you’ll see the heat map shift.
Why two subs often beat one
A single sub can be placed to sound great at one seat, but the seats either side can still have peaks and holes. Two or more subs drive the room’s modes from different places, so their peaks and dips partly cancel and the bass becomes more even from seat to seat. Harman research acoustician Todd Welti tested this in “Subwoofers: Optimum Number and Locations”. He found that four subs, one at the middle of each wall, gave the most consistent bass. Two subs at the midpoints of opposite walls came close and kept more low-frequency output.
The two subs tab runs those layouts for your room. Midpoint layouts usually win on evenness, while corner layouts play louder. If you add a second sub, feed both from the same output with a Y-splitter like the Amazon Basics RCA Y-adapter, then match their levels and delays. Our dual subwoofer setup guide and distance and delay guide walk you through it, and a DSP such as the miniDSP 2×4 HD lets you fine-tune each sub separately.
When placement isn’t enough
If the best practical spot still leaves a peak, EQ is the right tool: cutting a peak is easy and costs nothing in headroom. See our subwoofer EQ guide. Dips are different. Boosting a cancellation mostly wastes amplifier power, so fix dips by moving the sub, moving the seat or adding a second sub.
Bass traps help, but only if they’re thick. A deep corner trap like the ATS Acoustics corner bass trap makes a real difference from the upper bass up and calms decay times. Thin foam wedges sold as “bass traps” do very little below 100 Hz. If the ideal spot is far from your receiver, a 25 ft subwoofer cable or a wireless kit solves the wiring problem.
Frequently asked questions
Is the corner the best place for a subwoofer?
The corner gives the most output because it excites every mode in the room, but that also makes it the boomiest spot in many rooms. It’s a good choice when you need maximum loudness from a small sub. If you care more about tight, even bass, a spot along a wall, often the front or back wall midpoint, usually measures better. Check both in the calculator.
Can I put the subwoofer behind the sofa?
Often, yes. A sub on the back wall or right behind the seats is a common winner in the calculator, and it can feel punchier because it’s close to you. If it sounds disconnected from the front speakers, adjust the distance or delay setting in your receiver.
Does this work for open-plan rooms?
Only roughly. The model assumes four solid walls. If one side of your room opens into another space, bass leaks out that way and the modes in that direction are much weaker. Use the results as a guide and confirm with measurements or a sub crawl.
How accurate is the calculator?
It’s based on the standard model acoustic engineers use for rectangular rooms, so the pattern of good and bad spots is usually right. Exact peak and dip frequencies can shift a few hertz in a real room, and the depth of dips depends on furnishings. It’s best for narrowing down where to try first.
Does the size of my subwoofer change where it should go?
Not really. Placement is about the room and where you sit, not the driver. A bigger sub plays louder and deeper, which makes room problems more obvious, so placement matters even more with large subs. Our room size guide covers what size suits your space.