Method
How the math works
Every calculator on Actually, How Much? uses arithmetic you can redo on paper. This page is the reference for DIY vs. hire a professional. Updated 24 October 2026.
The formulas
- 1
Cash subtotal
Materials + tools or equipment + additional expenses. Blank tools and additional expenses count as zero.
- 2
Contingency
Cash subtotal × the contingency percentage, rounded to the nearest cent. A blank percentage counts as zero. It is not applied to your time or the quote.
- 3
DIY cash
Cash subtotal + contingency. This is the total DIY cash cost.
- 4
Value of your time
Hours × the hourly value you entered, rounded to the nearest cent.
- 5
Effective DIY cost
DIY cash + the value of your time.
- 6
Professional cost
The contractor's quoted price, unchanged.
- 7
Potential savings
Professional cost − effective DIY cost.
- 8
Cash difference
Professional cost − DIY cash. Your time is left out of this line.
- 9
Break-even hourly rate
(Professional cost − DIY cash) ÷ hours, when that rate is a positive number.
When there is no positive break-even rate
If hours are zero, time is worth nothing in the total and the hourly break-even is not calculated. The comparison is cash only.
If DIY cash, including contingency, is already above the quote, hiring is cheaper even if your time is free. The page says there is no positive rate.
If DIY cash matches the quote, the break-even hourly rate is zero. Any time value above zero makes hiring the lower total.
Rounding
Inputs allow at most two decimal places. Money is totaled in cents. A contingency that lands on half a cent rounds away from zero. The break-even rate is shown to the nearest cent.
Assumptions
Contingency stays on the DIY cash
The percentage is applied to materials, tools, and additional expenses, then rounded to the nearest cent. It is not applied to the value of your time, and it is not added on top of the contractor's quote. A quote is treated as the price you would pay. If that quote is only a rough guess, change the quote itself.
Tools are counted the way you enter them
The tool amount is included in full. If you already own a tool, or you will use it on later projects, enter only the share you want this one to carry. Enter 0 if tools should be left out.
Your hourly value is the one you type
The site does not look up wages, trades, or local prices, and it does not decide what your time should be worth.
The professional cost is one number
The quote is not itemized and it is not checked against other prices. Whatever you enter is the cost of hiring in this comparison.
Tax, permits, and disposal are optional lines you control
The calculator does not know your sales tax, permit fees, or dump fees. Put anything you want counted into additional expenses, or into the quote if the contractor already included it.
Currency is a label, not a conversion
CAD and USD change the currency name on the result. Amounts are not converted from one to the other.
Money is rounded to the cent
Contingency is the cash subtotal times your percentage, rounded to the nearest cent. Halves round away from zero. The value of your time is hours times the hourly figure you entered, also rounded to the nearest cent. The break-even hourly rate is shown to the nearest cent.
A negative difference is a real result
Potential savings are the quote minus the DIY total. When that number is negative, hiring is the smaller cost. The page says so in words as well as in the figure.
This is not a bid, a safety ruling, or permission to do the work
The result does not account for skill, warranty, insurance, code, or the chance that a project takes longer than the hours you typed, unless you have already put those concerns into the numbers.
Painting a room
The room-painting calculator is separate from the comparison above. Wall area for a rectangle is 2 × (length + width) × height. Doors and windows are subtracted once. A ceiling, if you include it, is length × width and uses the same coats and coverage. Paint before waste is area × coats ÷ coverage. Waste is added on top: 10% multiplies by 1.10. Containers round up.
Worked quantities, with no prices: a 12 ft by 10 ft room, 8 ft walls, a 21 sq ft door, a 15 sq ft window, ceiling excluded, two coats, 400 sq ft per gallon, and 10% waste. The wall area is 316 sq ft. Paint before waste is 1.58 gallons. After waste it is 1.738 gallons. One-gallon cans round up to 2.
Prices are whatever you type, in CAD or USD. Blank prices count as zero. The page does not look up store prices. The full notes sit on the painting calculator.
Use the calculator with your own numbers, and read the disclaimer before acting on a result.