Guide
28-Day vs Monthly Rental Billing: What Contractors Need to Know
Rental agreements are often billed on a 28-day cycle or a monthly cycle, and the two are easy to treat as the same thing. They aren’t. The difference changes when each new billing period starts — and that changes when a keep-or-return decision has to be made.
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The basics
Two ways to count a rental period
28-day cycle
A new billing period starts every 28 days after the rental starts — always exactly four weeks, whatever the month.
Monthly cycle
A new billing period starts on the same day of each month as the rental started. Months are 28 to 31 days long, so the period length varies.
The wording on a quote or agreement isn’t always this clear. Before you rely on either, check how your agreement defines the billing period. This guide explains the general mechanics; it isn’t accounting or legal advice, and your agreement’s terms are what count.
Why it matters
28-day rollovers drift earlier every month
Take a rental that starts on January 5. Here is when each new billing period starts under the two cycles:
| Period | 28-day | Monthly | Days earlier |
|---|---|---|---|
| 2nd | Feb 2 | Feb 5 | 3 |
| 3rd | Mar 2 | Mar 5 | 3 |
| 4th | Mar 30 | Apr 5 | 6 |
| 5th | Apr 27 | May 5 | 8 |
| 6th | May 25 | Jun 5 | 11 |
| 7th | Jun 22 | Jul 5 | 13 |
If the crew is used to thinking “it renews around the 5th,” a 28-day rental will already have started its next period days — and later in the year, weeks — before anyone looks at it.
Simple math
More periods in a year
Thirteen 28-day periods add up to 364 days. A monthly cycle has twelve periods in a year. So a rental kept all year on a 28-day cycle is billed for thirteen periods, against twelve on a monthly cycle.
An illustration, using a made-up rate of $2,800 per period for both: 13 × $2,800 = $36,400 on a 28-day cycle, against 12 × $2,800 = $33,600 on a monthly cycle. In practice, 28-day and monthly rates usually aren’t the same, so compare what you’re actually quoted. The point is that the number and the timing of charges are different.
Timing matters most at the end of a rental. If a new period begins before the equipment is picked up, how that period is charged — in full, prorated, or some other way — depends on your agreement. Either way, knowing the exact rollover date is what lets you decide before it arrives.
Tracking it
How to keep billing periods straight
- Record the billing period for every rental from the agreement, not from memory.
- Calculate each rollover from the actual start date, not the start of the month.
- For 28-day rentals, expect the next rollover to fall earlier on the calendar each month.
- Put the next rollover date in front of whoever makes the keep-or-return call, a few days ahead.
- Check invoices against the billing period and the dates you have on record (rental invoice reconciliation). If a bill runs past a return, see charged for rental equipment after returning it.
Rental Leak does this for every rental: it takes the billing period from the agreement (you confirm it), calculates each 28-day rollover from the start date and each monthly one from the start date’s day of the month, and shows the next charge. The iOS and Android apps can remind you before each rollover, and the dashboard shows what’s coming up — part of keeping rental costs under control. For the practical steps, see how to stop a rental before the next 28-day billing cycle.
Common questions
Is a 28-day billing cycle the same as a month?
No. A 28-day cycle is always exactly four weeks, so it starts each new period a little earlier on the calendar every month. A monthly cycle restarts on the same day of each month.
How many 28-day periods are in a year?
Thirteen 28-day periods cover 364 days, compared with twelve monthly periods in a year.
How do I work out the next 28-day billing date?
Count 28 days from the rental’s start date, then 28 more for each period after that. A rental that starts January 5 rolls February 2, March 2 and March 30.
What happens if equipment goes back a day after a 28-day rollover?
A new billing period has started. Whether it is charged in full, prorated or billed some other way depends on your rental agreement, so check the terms and know the rollover date ahead of time.
Keep reading
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