Free Bed Size calculator
Pick a mattress size to see its exact dimensions and the smallest room it fits in, or enter your room to find the largest bed it can hold — with standard US sizes and walking clearance, updated live, as you type.
On this page13 sections
Best for: Couples and the most popular all-round choice.
Uses standard US mattress sizes and a 24"-each-side / 36"-foot clearance. Add your bed frame and furniture — see how much space to leave.
Results are estimates. Consult a professional.
How the bed size calculator works
A bed size question runs in two directions, and this calculator answers both. Pick a mattress size and it returns that mattress's exact dimensions plus the smallest room you can walk around it in. Enter your room's width and length instead and it returns the largest standard mattress that still leaves room to move. Either way, the engine is the same: a mattress footprint plus a fixed walking clearance.
Standard mattress sizes and dimensions
There are six standard mattress sizes sold in the United States. The table below lists each one's footprint in inches, the clearance-only minimum room it needs, and who it usually suits. The minimum-room columns are computed the same way the calculator computes them, so they will always match the result above.
| Size | Mattress (in) | Min room (clearance only) | Recommended room (with furniture) | Best for |
|---|---|---|---|---|
| Twin | 38 × 75 | 7' 2" × 9' 3" | 8 × 10 ft | Children, teens, single sleepers |
| Twin XL | 38 × 80 | 7' 2" × 9' 8" | 9.5 × 10.5 ft | Taller single sleepers, dorms |
| Full (Double) | 54 × 75 | 8' 6" × 9' 3" | 9.5 × 10.5 ft | A roomy single, or a snug couple |
| Queen | 60 × 80 | 9' 0" × 9' 8" | 10 × 10 ft | Couples — the all-round favourite |
| King | 76 × 80 | 10' 4" × 9' 8" | 12 × 12 ft | Couples wanting maximum width |
| California King | 72 × 84 | 10' 0" × 10' 0" | 12 × 12 ft | Tall sleepers (extra length) |
Mattress dimensions are the standard US sizes (Casper / Amerisleep). The "min room (clearance only)" columns are 24 in per side + 36 in at the foot, rounded up to the inch. The "recommended room" column is the brands' comfortable size, which adds a nightstand and dresser on top of the walking clearance.
What size room do I need for each bed?
Most guides answer with a single rounded number — "a Queen needs a 10 by 10 room" — without showing the arithmetic. That figure quietly bundles in a nightstand and a dresser. The honest answer has two layers: the absolute minimum to physically walk around the bed, and the comfortable size once you add furniture. This calculator gives you the first exactly and cites the second.
The clearance-only minimum
Take the mattress, add a 24-inch walkway on each side, and add 36 inches at the foot. For a Queen that is 60 + 48 = 108 in (9 ft) wide and 80 + 36 = 116 in (9 ft 8 in) long — about 87 sq ft. That is the smallest room you can move around a Queen in, with nothing else in it.
The comfortable size, with furniture
Add a nightstand on each side and a dresser against a wall and the room grows. That is where the familiar "10 by 10 for a Queen, 12 by 12 for a King" numbers come from. Use the clearance-only figure to check whether a bed will physically fit; use the recommended figure when you are planning a comfortable, furnished bedroom.
A worked example: will a Queen fit my bedroom?
Priya has a spare bedroom that measures 11 ft × 12 ft and wants to know whether a Queen is the right size, or whether she could go bigger.
Step 1 — Find the Queen's minimum room
A Queen mattress is 60 × 80 in. Minimum width = 60 + (2 × 24) = 108 in, which is 9 ft. Minimum length = 80 + 36 = 116 in, which is 9 ft 8 in. So a Queen needs about a 9 ft × 9 ft 8 in room (≈ 87 sq ft).
Step 2 — Compare against the room
Priya's room is 132 in × 144 in. Both sides clear the Queen minimum (132 ≥ 108 and 144 ≥ 116), so a Queen fits with room to spare — about 2 ft of slack each way for furniture.
Step 3 — Could she go bigger?
A King needs 124 in × 116 in; a California King needs 120 in × 120 in. Her 132 × 144 room clears both. Of the sizes that fit, the King has the largest sleeping area, so the calculator reports King as the biggest bed her room can take.
How much space to leave around a bed
Walking clearance is the gap between the bed and the nearest wall or furniture. Too little and you turn sideways to pass; too much and you waste floor you paid for. The widely published targets scale with the bed.
- 24 in each side — the practical minimum to walk past the bed and make it. This is the figure the calculator uses.
- 30 in each side — more comfortable, and the target for Queen and larger beds where two people pass at once.
- 36 in at the foot — clears a chest, bench, or open closet door, and is the main walkway in most layouts.
- Head against a wall — no clearance needed there, which is why the length only adds the foot gap.
One side of the bed can drop below 24 in if it is rarely used or pushed against a wall, as in a child's room. To plan the whole floor — including the dresser and a reading chair — work out the room's square footage first, then subtract the bed's footprint and clearances.
Clearance targets follow the published bedroom-layout guidance from Casper and Amerisleep (24 in side / 36 in foot minimums) and interior-design space-planning guides, which recommend 30 in per side for larger beds.Which bed size is right for me?
Room size sets the ceiling; how you sleep sets the choice within it. The quick guide below pairs each size with the sleeper it suits, assuming the room can take it.
| Size | Width per sleeper | Right for |
|---|---|---|
| Twin / Twin XL | 38 in (one sleeper) | One person; Twin XL adds 5 in of length for taller sleepers and dorm beds. |
| Full (Double) | 27 in if shared | A single adult who likes space. Tight for two — each gets less width than a crib. |
| Queen | 30 in each | The default for couples and the most popular size sold. Fits most main bedrooms. |
| King | 38 in each | Couples who want as much personal width as a Twin gives one person — or who share with kids and pets. |
| California King | 36 in each | Tall sleepers: 4 in longer than a King, 4 in narrower. Best in long bedrooms. |
"Width per sleeper" splits the mattress width between two people. A King gives each person the full width of a Twin.
If two numbers tie — say a Queen and a King both fit — let sleep style break it. Restless sleepers, co-sleeping families and anyone sharing with a large pet gain the most from the extra King width. Solo sleepers rarely need more than a Full or Queen.
Bed size definitions
How accurate is this bed size calculator?
The mattress dimensions are exact — they are fixed industry standards, the same numbers every major brand publishes. The clearance arithmetic is exact too: width plus 48 inches, length plus 36 inches, converted straight to feet and centimetres. If your room measurements are right, the fit verdict is right.
What the calculator cannot see is your bed frame and furniture. A platform frame adds little; a frame with a thick footboard or storage drawers adds a few inches all round, and a nightstand eats into the side clearance. The clearance-only minimum is the hard floor; the recommended room sizes give the comfortable target. Measure the actual frame you plan to buy, not just the mattress, and leave the 24-inch walkway as a true minimum rather than a goal.
Frequently asked questions about the free Bed Size calculator
About this Bed Size calculator
This bed size calculator runs entirely in your browser. Nothing you enter — your mattress choice or your room measurements — is sent anywhere; every figure is computed on your device from the standard US mattress dimensions and a fixed walking-clearance rule, and updates the moment you change an input.
It is part of our home & garden calculators, alongside the rest of our free calculators. To plan the whole bedroom floor, start with the room's square footage, then subtract the bed's footprint and its clearances.