★ COMPARISONS · EVERYDAY · BATH VS SHOWER
Shower wins by $1,055.60 over 10 years. A shower costs $76.44 a year against $182.00 for a bath, because an 8-minute shower uses 16.80 gallons and a bath uses 40.00 gallons. Enter your own shower minutes, flow rate and tub fill to compare a bath and a shower on your numbers.
A shower and a bath are priced on the same thing: gallons of hot water. A shower uses the minutes times the flow rate, and a bath uses the tub fill, and every gallon costs the water price plus the heating price. This calculator prices both sides over the same 10 years and the same number of washes, and works out which one wins, which one wins a year, and where the two sides break even — so the number you get is the number you actually pay.
A shower and a bath are priced on the same thing: gallons of hot water. The cost per gallon is the water price divided by 1,000 plus the heating cost per gallon: $4.50 ÷ 1,000 = $0.0045 for the water, plus $0.008 for the heating, which is $0.0125 a gallon. The heating figure is for gas at $1.50 a therm, an 80% efficient heater and a 50°F rise, which is the rise from cold water to a comfortable shower. The shower gallons a wash are the shower minutes times the flow rate, and the bath gallons a wash are the tub fill. The cost a wash is the gallons times the cost per gallon, the cost a year is the cost a wash times the washes a week times 52 weeks, and the 10-year cost is the cost a year times the horizon. The winner is the smaller 10-year cost, and the gap between the two is how much the winner wins by.
At the defaults — 7 washes a week, shower 8 minutes, flow 2.1 gpm, tub 40 gallons, water $4.50 per 1,000 gallons, heating $0.008 a gallon, 10 years — the shower uses 8 × 2.1 = 16.80 gallons a wash, which costs 16.80 × $0.0125 = $0.21 a wash, which is $0.21 × 7 × 52 = $76.44 a year and $76.44 × 10 = $764.40 over 10 years, while the bath uses 40.00 gallons a wash, which costs 40.00 × $0.0125 = $0.50 a wash, which is $0.50 × 7 × 52 = $182.00 a year and $182.00 × 10 = $1,820.00 over 10 years — so the shower wins by $1,820.00 − $764.40 = $1,055.60.
| Case | Shower 10-year | Bath 10-year | Winner |
|---|---|---|---|
| 8-min shower (default) | $764.40 | $1,820.00 | Shower by $1,055.60 |
| 5-min shower | $477.75 | $1,820.00 | Shower by $1,342.25 |
| 15-min shower | $1,433.25 | $1,820.00 | Shower by $386.75 |
| Flow 1.5 gpm | $546.00 | $1,820.00 | Shower by $1,274.00 |
| Flow 2.5 gpm | $910.00 | $1,820.00 | Shower by $910.00 |
| Tub 30 gal | $764.40 | $1,365.00 | Shower by $600.60 |
| Tub 60 gal | $764.40 | $2,730.00 | Shower by $1,965.60 |
| Water $9.00/1,000 gal | $1,039.58 | $2,475.20 | Shower by $1,435.62 |
| Flip: 25-min shower | $2,388.75 | $1,820.00 | Bath by $568.75 |
Setup: 7 washes a week, shower 8 minutes, flow 2.1 gpm, tub 40 gallons, water $4.50 per 1,000 gallons, heating $0.008 a gallon, 10 years.
Line 1 — the cost per gallon. $4.50 ÷ 1,000 = $0.0045 for the water, plus $0.008 for the heating, which is $0.0125 a gallon.
Line 2 — the shower gallons. 8 × 2.1 = 16.80 gallons a wash.
Line 3 — the shower cost. 16.80 × $0.0125 = $0.21 a wash, and $0.21 × 7 × 52 = $76.44 a year, and $76.44 × 10 = $764.40 over 10 years.
Line 4 — the bath gallons. The tub fill is 40.00 gallons a wash.
Line 5 — the bath cost. 40.00 × $0.0125 = $0.50 a wash, and $0.50 × 7 × 52 = $182.00 a year, and $182.00 × 10 = $1,820.00 over 10 years.
Line 6 — the winner. $1,820.00 − $764.40 = $1,055.60 to the shower. The shower costs $76.44 a year against $182.00 a year for the bath.
5-minute shower: the shower uses 5 × 2.1 = 10.50 gallons a wash, which costs 10.50 × $0.0125 = $0.13 a wash, which is $0.13 × 7 × 52 = $47.78 a year and $477.75 over 10 years, while the bath stays $1,820.00 — so the shower wins by $1,342.25. A short shower is the cheapest wash here, because every minute costs 2.1 gallons.
15-minute shower: the shower uses 15 × 2.1 = 31.50 gallons a wash, which costs 31.50 × $0.0125 = $0.39 a wash, which is $143.33 a year and $1,433.25 over 10 years, while the bath stays $1,820.00 — so the shower wins by $386.75. A long shower nearly catches the bath, because 31.50 gallons is close to a 40-gallon tub.
Flow 1.5 gpm: the shower uses 8 × 1.5 = 12.00 gallons a wash, which costs 12.00 × $0.0125 = $0.15 a wash, which is $54.60 a year and $546.00 over 10 years, while the bath stays $1,820.00 — so the shower wins by $1,274.00. A low-flow head is the cheapest upgrade here: it cuts the shower gallons by almost a third with no change in habit.
Flow 2.5 gpm: the shower uses 8 × 2.5 = 20.00 gallons a wash, which costs 20.00 × $0.0125 = $0.25 a wash, which is $91.00 a year and $910.00 over 10 years, while the bath stays $1,820.00 — so the shower wins by $910.00. A high-flow head still beats the bath, but it costs $36.40 a year more than the 2.1 gpm head.
Tub 30 gal: the bath uses 30 gallons a wash, which costs 30 × $0.0125 = $0.38 a wash, which is $136.50 a year and $1,365.00 over 10 years, while the shower stays $764.40 — so the shower wins by $600.60. A shallow bath is cheaper than a full one, but it still costs nearly twice the shower.
Tub 60 gal: the bath uses 60 gallons a wash, which costs 60 × $0.0125 = $0.75 a wash, which is $273.00 a year and $2,730.00 over 10 years, while the shower stays $764.40 — so the shower wins by $1,965.60. A deep soak in a big tub is the dearest wash here, because every extra gallon pays the full $0.0125.
Water $9.00 per 1,000 gallons: the cost per gallon rises to $9.00 ÷ 1,000 + $0.008 = $0.0170 a gallon, so the shower costs 16.80 × $0.0170 = $0.29 a wash, which is $103.96 a year and $1,039.58 over 10 years, and the bath costs 40.00 × $0.0170 = $0.68 a wash, which is $247.52 a year and $2,475.20 over 10 years — so the shower wins by $1,435.62. Dear water widens the gap, because the bath uses more gallons and every gallon costs more.
Reverse — the break-evens: the shower ties the bath at a length of 19.05 minutes — 40 ÷ 2.1. It ties at a flow of 5.00 gpm — 40 ÷ 8. And the tub ties the shower at a fill of 16.80 gallons — 8 × 2.1. Below those numbers the shower wins, and above them the bath wins.
Flip — 25-minute shower: the shower uses 25 × 2.1 = 52.50 gallons a wash, which costs 52.50 × $0.0125 = $0.66 a wash, which is $238.88 a year and $2,388.75 over 10 years, while the bath stays $1,820.00 — so the bath wins by $568.75. A very long shower flips the answer: the shower minutes are the one input that can turn the whole comparison around, because every minute costs 2.1 gallons.
The model assumes the same number of washes every week for 10 years, the same water and heating prices, and the same shower length and tub fill, with 52 weeks in a year. It assumes the heating cost is $0.008 a gallon, for gas at $1.50 a therm, an 80% efficient heater and a 50°F rise, and it assumes the water is heated for every wash: a cold rinse would cost only the water price of $0.0045 a gallon. It leaves out the cost of the showerhead, the tub and the water heater, and it leaves out soap, shampoo and towels, which are not counted on either side. Rounding convention: money is rounded to cents, gallons to 2 decimals, and all figures are computed from unrounded values, rounded only for display.
| Output | Formula | What it means |
|---|---|---|
| Cost per gallon | water ÷ 1,000 + heating | $0.0125/gal. |
| Shower gallons/wash | minutes × flow | 16.80 gal. |
| Shower cost/wash | gallons × cost/gal | $0.21. |
| Shower cost/yr | cost/wash × washes × 52 | $76.44. |
| Shower 10-year cost | cost/yr × horizon | $764.40. |
| Bath gallons/wash | tub fill | 40.00 gal. |
| Bath cost/wash | gallons × cost/gal | $0.50. |
| Bath cost/yr | cost/wash × washes × 52 | $182.00. |
| Bath 10-year cost | cost/yr × horizon | $1,820.00. |
| Winner | bath 10-year − shower 10-year | Shower wins by $1,055.60. |
| 5-min shower | same model, 5 min | 10.50 gal, $0.13/wash, $47.78/yr, $477.75, Shower wins by $1,342.25. |
| 15-min shower | same model, 15 min | 31.50 gal, $0.39/wash, $143.33/yr, $1,433.25, Shower wins by $386.75. |
| Flow 1.5 gpm | same model, 1.5 gpm | 12.00 gal, $0.15/wash, $54.60/yr, $546.00, Shower wins by $1,274.00. |
| Flow 2.5 gpm | same model, 2.5 gpm | 20.00 gal, $0.25/wash, $91.00/yr, $910.00, Shower wins by $910.00. |
| Tub 30 gal | same model, 30 gal | Bath $0.38/wash, $136.50/yr, $1,365.00, Shower wins by $600.60. |
| Tub 60 gal | same model, 60 gal | Bath $0.75/wash, $273.00/yr, $2,730.00, Shower wins by $1,965.60. |
| Water $9.00/1,000 gal | same model, $9.00 | Cost $0.0170/gal, shower $0.29/wash, $103.96/yr, $1,039.58; bath $0.68/wash, $247.52/yr, $2,475.20, Shower wins by $1,435.62. |
| Flip: 25-min shower | same model, 25 min | 52.50 gal, $0.66/wash, $238.88/yr, $2,388.75, Bath wins by $568.75. |
| Reverse: break-even shower length | tub fill ÷ flow | 19.05 min. |
| Reverse: break-even flow | tub fill ÷ minutes | 5.00 gpm. |
| Reverse: break-even tub fill | minutes × flow | 16.80 gal. |
The math is exact for the numbers you enter: the cost per gallon is the water price divided by 1,000 plus the heating cost per gallon, the shower gallons are the minutes times the flow rate, the bath gallons are the tub fill, and the 10-year cost is the cost a year times the horizon. What the model cannot do is measure your shower or your tub for you: time the shower, and check the flow rate on the showerhead and the water price on the bill. It assumes the heating cost is $0.008 a gallon, for gas at $1.50 a therm, an 80% efficient heater and a 50°F rise, and an electric heater or a colder winter will move that figure. It leaves out soap, shampoo and towels, and it assumes the same washes every week for 10 years. For the tub itself, see bathtub size chart; for the water in a bottle, see bottled water vs filter.
Bright Side Kit. "Bath vs Shower Cost Calculator: Water & Energy 2026." https://brightoolbox.com/bath-vs-shower-calculator/ Accessed October 25, 2026.A shower is cheaper. A shower costs $76.44 a year against $182.00 for a bath, and $764.40 over 10 years against $1,820.00 for a bath, so the shower wins by $1,055.60. An 8-minute shower uses 16.80 gallons, and a bath uses 40.00 gallons.
Compare the cost over the same years and the same washes. The cost per gallon is $4.50 ÷ 1,000 + $0.008 = $0.0125. The shower uses 8 × 2.1 = 16.80 gallons a wash, which costs $0.21, or $76.44 a year. The bath uses 40.00 gallons a wash, which costs $0.50, or $182.00 a year. Over 10 years the shower costs $764.40 and the bath costs $1,820.00.
16.80 gallons for an 8-minute shower. The gallons are the minutes times the flow rate: 8 × 2.1 = 16.80 gallons. A 5-minute shower uses 10.50 gallons, and a 15-minute shower uses 31.50 gallons.
40.00 gallons for a standard tub. The bath gallons are the tub fill: a 30-gallon fill uses 30 gallons and costs $0.38 a wash, and a 60-gallon fill uses 60 gallons and costs $0.75 a wash.
$76.44 a year. A shower costs $0.21 a wash, and $0.21 × 7 washes a week × 52 weeks is $76.44 a year. A 5-minute shower costs $47.78 a year, and a 15-minute shower costs $143.33 a year.
When the shower runs past 19.05 minutes. A 25-minute shower uses 52.50 gallons and costs $238.88 a year, while the bath costs $182.00 a year, so the bath wins by $568.75 over 10 years. The break-even flow is 5.00 gpm, and the break-even tub fill is 16.80 gallons.
Yes. At 1.5 gpm an 8-minute shower uses 12.00 gallons and costs $54.60 a year, against $76.44 a year at 2.1 gpm, so the head saves $21.84 a year. Over 10 years the low-flow shower costs $546.00 against $764.40.
Dear water widens the gap. At $9.00 per 1,000 gallons the cost per gallon is $0.0170, so the shower costs $103.96 a year and the bath costs $247.52 a year, and the shower wins by $1,435.62 over 10 years, against $1,055.60 at $4.50.