If you've ever opened a pay run or invoice and noticed the total comes out a penny or two different from what you'd get by multiplying the hourly rate by the total hours, this is expected. The number is correct. This article explains what's happening, why, and what to do if you need the total to align with a manual calculation.
How Birdie prices each visit
Birdie prices each visit one at a time, using the exact visit duration down to the second. We do not round the duration. We only round the final money amount for each visit, to the nearest penny, because currency cannot be split into fractions smaller than that.
For example, a 15-minute visit at £12.21 per hour is priced as:
0.25 hours × £12.21 = £3.0525
That rounds to £3.05 for the visit total.
Every visit in a pay run or invoice is treated the same way: priced, then rounded. The pay run or invoice total is the sum of those rounded visit values.
Why the total may not equal rate × hours
When several short visits are summed together, the fractions of a penny lost or gained on each rounding can add up to a difference of a penny or two compared to a bulk calculation.
Here are two worked examples, showing this happening in both directions:
Example 1: total slightly lower than rate × hours
Four 15-minute visits at £12.21 per hour:
Each visit: 0.25 × £12.21 = £3.0525, rounded to £3.05
Sum of four visits: 4 × £3.05 = £12.20
Rate × hours: 1.00 × £12.21 = £12.21
Total shown: £12.20 (1p lower)
Example 2: total slightly higher than rate × hours
Four 15-minute visits at £12.71 per hour:
Each visit: 0.25 × £12.71 = £3.1775, rounded to £3.18
Sum of four visits: 4 × £3.18 = £12.72
Rate × hours: 1.00 × £12.71 = £12.71
Total shown: £12.72 (1p higher)
In both cases, the individual visit values are correct. The small difference only appears when you compare the sum of visits to a single bulk calculation.
Why we round each visit independently
Pricing each visit as its own line item is what gives your pay run and invoice a transparent, auditable trail. Every visit a carer delivers can be traced back to a specific payable amount in pennies, so pay sheets, invoices, and reconciliation with your downstream accounting tools all line up at the visit level.
Birdie also uses banker's rounding (sometimes called round half to even) when a visit value lands exactly on half a penny. A simpler "always round up" rule would create a small systematic bias over thousands of visits, slowly inflating totals.
Banker's rounding alternates direction based on the nearest even number, so over time there is no drift in either direction. This is a standard approach across accounting and financial systems for the same reason.
What to do if you need totals to match a manual calculation
You have a few options, depending on how your finance process is set up:
Choose hourly rates that divide cleanly. If most of your visits are 15-minute increments, an hourly rate that is divisible by 4 produces no rounding gap. For 30-minute increments, an even-pence rate is enough.
Use the per-visit breakdown. The CSV export from the pay dashboard or invoice dashboard shows each visit's individual total, so you can cross-check the maths line by line.
Add a small adjustment. If a payer requires the final total to match a specific bulk calculation (some local authorities do), you can record a deduction or an extra charge on the affected pay sheet or invoice to reconcile.
FAQs
Is the £12.20 total wrong if my hourly rate is £12.21?
No. The total is the correct sum of what each visit is actually worth once rounded to the nearest penny. The £12.21 rate is the hourly rate on the rate card, used to price each visit individually, not to set the total directly.
Will banker's rounding cause carers to be underpaid over time?
No. Banker's rounding alternates direction on half-penny ties, so across a carer's full set of visits there is no built-in bias up or down. Some pay runs end a penny lower than rate × hours, others a penny higher.
Does this affect National Living Wage calculations?
The NLW tag in Birdie uses the exact, unrounded total of worked hours and pay to assess whether a carer has been paid at or above the legal minimum. The 1p differences described here do not interact with the NLW calculation.
Can I switch Birdie to a different rounding method?
Not at the moment. Banker's rounding is applied consistently across pay runs and invoices. If your payer requires a specific rounding method, you can either align your rate card to avoid the gap, or use a deduction or extra charge on the affected pay sheet or invoice.